Synthroid Overdose: Signs & Symptoms You’re Taking too Much

Synthroid Overdose: Signs & Symptoms You’re Taking too Much

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Are you concerned that your dose of Synthroid is too high?

That may be the case, especially if you are experiencing symptoms such as hair loss, heart palpitations, and heat intolerance. 

The good news is that Synthroid overdose can be easily treated by simply reducing your dose. 

This article will outline the major side effects associated with taking too much Synthroid, what to do about it, the long-term (and short-term) consequences of taking too much, and how to determine your optimal dose

Let’s jump in: 

Thyroid Medication And Dosing

Synthroid is one of (if not the most) commonly prescribed medications in the United States

This is important for 2 reasons:

#1. Because it indicates that a very large number of people have hypothyroidism (a discussion for another post). 

And #2. Because so many people are using this medication, there is a high likelihood that some people are being overdosed (1) and some people are being over-dosed. 

It’s hard to quantify exactly how many people are being mismanaged when it comes to their thyroid medication because of a number of variables but we do know that it is quite a lot. 

And this is very important. 


Because overdosing on thyroid medication is not good for your short-term and long-term health (2).

Your thyroid plays an important role in regulating several systems in your body and in order for these systems to work properly you must be taking the exact right amount of medication. 

Too much and you will experience the symptoms of an overdose and too little and you will experience the symptoms of hypothyroidism. 

Signs You Are Taking Too Much Synthroid

So how do you know if you are taking too much Synthroid?

The best and easiest way to determine is by looking at your symptoms. 

Your body will tell you when something is wrong or off! All you have to do is listen. 

Common symptoms of Synthroid overdose include:

  • Increased hair loss
  • Weight loss (sometimes but not always)
  • Tremors in the extremities
  • Jittery sensation
  • Heart palpitations
  • Anxiety
  • Flushing of the skin
  • Heat intolerance (not able to stand hot environments)

These are the most common negative side effects of taking too much Synthroid and they are usually felt rather quickly and within days of increasing your dose. 

They also can develop slowly over a period of time if your dose is only slightly too high for your body. 

Rare but serious side effects of long-term Synthroid overdose include:

  • Osteoporosis or decreased bone density
  • Heart enlargement
  • Atrial fibrillation
  • Chest pain
  • Shortness of breath
  • *If you experience any of these symptoms you should seek medical care as soon as possible.

This list of rare side effects is far more serious than the ones listed above but they usually take a longer period of time to set in. 

Thyroid lab tests that indicate your dose may be too high include:

  • Suppressed TSH – This should be differentiated from a low TSH which. A Suppressed TSH means that your TSH is undetectable. A low TSH does not always increase your risk of developing the negative side effects listed above. 
  • High free T4
  • High free T3

If your dose of Synthroid is truly too high then you will also notice changes in your thyroid lab tests as well. 


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The Complete List of Thyroid Lab tests:

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What Are the Long-Term Dangers of Being Over-Dosed?

Some people prefer a slight overdose when it comes to their thyroid medication. 


Because your thyroid helps to regulate your metabolism by turning on cellular function. 

The more thyroid hormone you have the higher your metabolism will be, the more fat you will burn at rest, and the more energy you will have. 

While this does sound appealing, it doesn’t come without a cost. 

As you rev up the cellular machinery in your body you rev up more than just your fat-burning potential. 

Increasing your thyroid dose also puts excess strain both on your bone density and on your heart tissue. 

Using a consistently high dose of Synthroid puts you at an increased risk for developing osteoporosis (3) (decreased bone density) and heart conditions such as atrial fibrillation (4).

The absolute risk is not well defined and there are some studies that show that suppressing the TSH does NOT cause these conditions (5), but they are still important to consider for each person. 

Even if your risk is increased for developing these conditions, though, doesn’t mean that you will ALWAYS experience them. 

It may be that taking a higher dose of Synthroid increases your risk of both osteoporosis and atrial fibrillation, but the risk may only increase from say 1% up to 3-4% per person per year. 

These numbers are made up (because we don’t actually know what they are), but these are plausible values based on my own experience and looking at the data. 

How Long Does Synthroid Stay in your System? 

Synthroid, because it is a T4-only thyroid medication, has a half-life of around 5-7 days (6).

What does that mean?

It means that it will take 5 half-lives for this medication to be nearly completely eliminated from your system. 

If you do the math (7 days x 5 half-lives) you find that Synthroid will be in your system for a total of about 35 days. 

By the 35-day mark, you will most likely metabolize the majority of thyroid medication. 

And by metabolism, I mean that your body will basically use up all of that thyroid hormone for cellular function. 

This is both good and bad. 

Bad in the sense that if you take too much thyroid medication it may remain in your system for a long period of time and good in the sense that if you miss a dose here or there it’s probably not going to affect you because you have a significant amount built up in your system. 

But it’s important to note that just because it’s in your system for 35 days doesn’t mean that it will be equally potent throughout all of those days. 

For instance:

Around day 17-18 the concentration of Synthroid will be about half of what you took originally. 

Finding Your Optimal Dose of Synthroid

So how are you supposed to find your optimal dose of Synthroid?

The answer that most people look to is their thyroid lab tests. 

And this is a great starting point, but it’s not sufficient by itself. 

Most people, when they look at their thyroid lab tests, focus solely on the TSH as a marker of thyroid function. 

And while the TSH is a potentially great marker, it’s not perfect and it shouldn’t be the only thing you look at.

More valuable measurements may be found by evaluating your free thyroid hormone concentrations. 

And by free thyroid hormone levels, I am referring to both Free T3 and Free T4

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These markers tell you exactly how much thyroid is floating around in your bloodstream and give you an idea if you are absorbing and utilizing the Synthroid you are taking by mouth. 

If you focus only on the TSH you miss the information provided by looking at these levels. 

The TSH only gives you information about your pituitary gland (7) and it doesn’t give you information about the absolute levels of free thyroid hormone levels in your body. 

But beyond your free thyroid hormone levels, you also want to look at one other very important factor… 

Your symptoms!

In other words:

How are you feeling? Are you noticing an improvement in the symptoms that brought you to the doctor in the first place? Are you feeling any better? Is your weight normalizing? Is your hair loss slowing down? 

All of these questions are things that you should be thinking about as you alter your dose!

As you alter your dose of Synthroid you should feel BETTER, not worse. 

As you do these things (evaluate both your free thyroid hormone levels and your symptoms) you will find your optimal dose. 

What to do if you are Experiencing Overdose Symptoms

The good news is that overdose symptoms can be easily solved by adjusting your dose of Synthroid. 

I don’t recommend that you make any changes to your Synthroid dose without first consulting your doctor, but the answer to solving your issue is usually as easy as reducing your total dose. 

Let’s use this as an example:

Say that you are taking 100mcg of Synthroid each day. 

Previously you were taking 75mcg per day and feeling pretty good, but once you started taking the 100mcg dose you started to notice increased hair loss, heart palpitations, a jittery feeling, and some anxiety. 

You also found that your TSH was low and your free T4 was high after thyroid blood testing. 

This is a pretty classic example of Synthroid overdosing. 

So what do you do?

The most obvious answer is to reduce your dose back to where you felt “normal” which would be around 75mcg of Synthroid each day. 

Not all cases are this clear-cut, but this is the logic that you should apply to your situation. 

In reality, you may find that you need slightly more than 75mcg but less than 100mcg and you might find that your ideal dose is really closer to 88mcg per day. 

This can be teased out as you evaluate your lab tests and as you follow your symptoms. 

What if you Accidentally Double or Triple your Normal Dose of Synthroid? 

In most cases, this won’t be a huge deal (8).

You may feel jittery or anxious for about a week or so, but the side effect should fade rapidly over a few days. 

If you take an excessively high dose you may be tempted to compensate by reducing your dose the next few days, but this isn’t actually a good idea. 

thyroid lab tests after acute ingestion of thyroxine

It’s best not to play chemist when it comes to your medications and instead stick to your regular program as if the change in your dosing didn’t happen. 

By adding more complexity to your dosing equation (by skipping other doses) you risk causing more side effects down the road which can confound and confuse you further. 

If after taking a high dose you are experiencing symptoms that are troublesome then you can reach out to your Doctor. 

In some cases, they may want you to use a medication known as a beta-blocker which can help reduce the side effects you are experiencing. 

Even if you take a high dose of Synthroid in 1 day, the consequences should not be long-lasting or severe. 


Synthroid is an incredibly common medication that is prescribed for treating hypothyroidism and Hashimoto’s thyroiditis. 

Because it is so commonly used, the percentage of people who temporarily take too much medication is quite high!

The good news is that in most cases, the side effects and consequences are not severe and should fade on their own over a period of a few days. 

Synthroid has a half-life of about 5-7 days which means that it is normally eliminated entirely from your system in about 30-35 days

You can treat overdose symptoms usually by simply reducing your dose of thyroid medication. 

Also, you can find your optimal dose of Synthroid by evaluating both your thyroid lab tests and by keeping an eye on your symptoms. 

Now I want to hear from you:

Are you suffering from Synthroid overdose symptoms?

What dose are you currently taking?

Do you feel your dose is too high or too low?

Leave your questions or comments below! 









signs you are taking too much thyroid medication for your body

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About Dr. Westin Childs

Hey! I'm Westin Childs D.O. (former Osteopathic Physician). I don't practice medicine anymore and instead specialize in helping people like YOU who have thyroid problems, hormone imbalances, and weight loss resistance. I love to write and share what I've learned over the years. I also happen to formulate the best supplements on the market (well, at least in my opinion!) and I'm proud to say that over 80,000+ people have used them over the last 7 years. You can read more about my own personal health journey and why I am so passionate about what I do.

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60 thoughts on “Synthroid Overdose: Signs & Symptoms You’re Taking too Much”

  1. Hey Dr. Childs,
    I think this is what’s going on in my body. I started out with FT3 mid range, FT4 low, TSH 0.9, elevated RT3-could be due to stress and experiencing neuropathic symptoms (burning arms, tingling). In an attempt to figure out whether my body is in an hypothyroid state, I increased my dose from 75mcg to 98mcg. After two weeks, the burning got worse, hair loss, feeling jittery and shortness of breath. Conclusion, 98mcg is too much. Is 75mcg too little. I don’t know. We’ll see. The neuropathy could be related to the thyroid (in this regard it would be nice, if you could add a blog post with this topic in the future) or not. I know that my labs are not in the optimal range, but I am not sure how to get them there. Maybe it is, as you describe it above, just a matter of a little bit more. Happy Monday!

  2. I experienced some symptoms of hypothyroidism, so we changed my dose from 75mcg to 94mcg. starting out with tsh 0.9, ft4 0.9(low), ft3 2.6 (mid range). after 2 weeks I felt a bit anxious, hair started falling out, shortness of breath. I guess the dose was too high for me even though the blood test showed improvements tsh 0.9, ft3 3.0, ft4 1.5. the optimal dose is probably somewhere in between 75 and 94mcg.

  3. I have been taking 25 mcg of thyroid med for about 6 months. I didn’t catch that the pharmacy refilled my script for 50mcg. My symptoms sent me to my cardiologist and he figured out what was going on from my labs. I had taken the higher dose for only 10 days. I have a pace maker and occasional A-Fib. Don’t know if my existing heart issues increased my symptoms but they were pretty intense. I have been back on 25 mcg for 6 days. Symptoms are diminishing but definitely not gone. How long would you estimate it will take to eliminate the overdose from my system? Can taking an overdose for only 10 days cause this many problems?

    • Hi Bonnie,

      The extra medication should be out of your system within about a month or so! And yes, it just depends on how sensitive you are to the changes in your dose.

  4. Hi Dr. Childs. I have Hashimoto’s. I have been taking levothyroxine 100mcg and liothyronine 5mcg both once daily in the morning. It was definitely making me feel much better but I was still feeling lightheaded all the time. I went to a new endocrinologist and he took me off of my current medication and put me on 90mg NP Thyriod by Acella. Exactly two weeks after being on this medication I was feeling absolutely horrible. Extreme fatigue, confusion, slurred speech, blurred vision, headache, feeling like I was going to faint, increased appetite and very emotional. These were also my symptoms before I was put on thyriod medication in the first place. I called my doctor to explain my symptoms and he told me they weren’t thyroid related symptoms. I then called my old doctor and he told me to take half of my levothyroxine, which made it 50MCG. Within one hour I started feeling better. By evening all symptoms were gone. He then instructed me to go back on my old medication and stop taking the NP Thyroid. Did this medication just not work for me or was it the wrong dose? I was very disappointed that the prescribing doctor dismissed my horrible symptoms. Have you seen this happen before? Why is Hashimoto’s causing me lightheadedness? Thank you for your time.

    • Hi Kristin,

      It sounds like you were not dosed appropriately. Before you switched medications you were taking 100mcg of T4 and 5 mcg of T3, after the switch you were taking 57mcg of T4 and 13mcg of T3. Most doctors are clueless when it comes to switching medications so they often underdose which causes the symptoms you experienced.

  5. Hello Dr.

    I am 31 weeks pregnant. My Levothyroxin dose has been increased from 100 to 125 when I was 8 weeks. After taking 125 for six weeks, I did the blood work and found out that 125 was too much. The Dr. reduced it 112. Since then I’m on 112. Last month the pharmacy told me that they don’t have 112 tablet and suggested to take 1 and half of 75. I started doing that for few days. This morning I found out that I have been taking 1 and half of the 125 for about two weeks. The colors are very similar. Even though I don’t have any symptoms, I am very much worried. Does it harm the baby? I have appointment after two days. What should I do till then?

  6. I am experiencing the symptoms of too much synthroid in my system. I have been having heart palpitations, bad shakiness in my hands and legs it feels like severe anxiety. I have been feeling awful. My previous endocrinologist said that my dose was too high and that previous tests by my primary doctor were very off and she did not notify me. So I have been taking .150 for over a year and these symptoms just hit me really hard. I found a new doctor that said my symptoms were all because of too much synthroid, he has dropped me to .125, even by me stopping it for 2 weeks my levels are getting close to normal range. He wants me to begin taking the new dose Monday.
    He suggested putting me on a beta blocker for my palpitations. My question is how long can these symptoms last its just so uncomfortable and I am thinking about taking the Beta Blocker but am nervous about taking it.

    • Hi Anne,

      They can last a few days up to several weeks as your body metabolizes and utilizes the extra thyroid hormone.

    • Hi Anne. I just learned I have been taking too high of a dose and am having the same systems as you – fast heart beat, anxiety, plus weight loss. My dose is being lowered. I am wondering how long it took before you felt better? Thanks.

      • I am experiencing this now too – increase heart rate ( was put on metoprolol, ) anxiety , fatigue. My dose is lowered from 100 mcg to 88 mcg of synthroid . Im on my 5th day of the new dose. Palpitations is managed, but fatigue is too much. How long did it take you before you feel better?

        • Hello,

          I am experiencing this exact same thing. My levels were checked 3 days after i delivered by daughter and my dose was increased (normal t4, TSH only slightly elevated). I went from 50 mcg to 75 mcg daily. I was on this for about 9 weeks then ended up in the ER with severe symptoms (blacking out, heart racing, muscle tightening, etc.). I have been off synthroid completely now for 23 days, but I am still having symptoms off an on. Last night my muscles started tightening involuntarily and today I am generally weak, jittery, lightheaded.

          Any insights on when you all started to feel better once your dose was decreased/stopped?

  7. Hello there,
    Where do I start, Total TT 3 years ago, a mess since, been on Synthroid and different doses, cannot find correct dose the last dose of Synthroid was 88 a year ago, most doses give me palpitations or extreme tiredness, I tried armor , I gained 10 lbs within 4 months, and started swelling legs and arms. I was on 90 mcg. I am now back on Synthroid, back to feeling crappy, I’m lightheaded and dizzy more often than not, and I’m on a bigger dose than I have ever been I’m on 137. I’m sure it’s too high, considering my last Synthroid was 88. I am not handling the dizzyness lightheadedness well, make me feel like I’m going to pass out, or have a stroke, I just get all tingling. He also prescribed me t3 when he gave me the Synthroid 6 weeks ago, but I haven’t touched it yet. Any suggestions? I sure would appreciate it.

    • I am not a doctor. I can’t take Synthroid because it has a binder in it that does not agree with my body so I have to stick with levothyroxine. I was told by the pharmacist that the different manufacturers of levothyroxine can vary greatly in the dose so if you’re taking .125 from one manufacture it could vary by up to 80% from a different manufacturer so it’s important to stick with the same manufacturer if you’re on levothyroxine. If you’re having other issues on Synthroid consider maybe that the binder is not agreeing with your body. that was by experience so hopefully that helps you ask some additional questions. I wish you the best!

      • Hi Laura,

        That information from your pharmacist is mostly incorrect. The dose can vary but it can only vary +/-5%. In other words, the dose must be within 95% to 105% of the stated dose. If that was 100mcg then the dose must be within 96 to 104mcg per capsule. This is different from NDT which can be within +/- 10% of the stated dose.

  8. Hi Dr Childs!

    Three years ago, I had mysterious bouts chronic urticaria/idiopathic anaphylaxis (not allergic to anything except mushrooms…) led to discovering my hypothyroidism, and was put on 75mg of levothyroxine. It was like a miracle, and even got rid of my hives and allergy symptoms completely. I got mono in December, and it destroyed my immune system, and I also lost about 10 pounds. I was having all they symptoms of overdose, with these intense and intolerable flushing attacks which made me turn bright red. This was happening every day. My doctor lowered it to 50mg and that worked for~ two weeks, and now I’m back to overdose symptoms, and he refuses to lower it again. I can’t deal with the anxiety, the palpitations, and the flushing. He said there’s nothing he can do, I have to wait another month, that I’ll adjust. I broke down and started crying in the office, which is embarrassing enough- it’s debilitating, and horrible, but is that true? I think he thinks I’m being overly dramatic, but I’m really not! This is the third doctor I’ve had to switch to because they all eventually leave the city, and I thought I finally found a good place. Now I feel alone, frustrated, and not taken seriously. I feel like if I stop for a few days to give me a break from the flushing, I’ll be gambling with random anaphylaxis again. I don’t know what to do or how to convince my dr this is seriously affecting my daily life. I have an appointment with another doctor, but can’t get in to see them until end of April. I feel stuck.

    Thank you!

  9. I have been suffering from balance problems for 2.5 months. My ENT concluded it is not ear related. I have been on 150/175 Synthroid for about a year and have been taking fairly high doses for 15 years since oral cancer radiation therapy ruined my thyroid. My last test showed a TSH of .138 shows I have been overdosing. I’ve reduced my dose to 125/150. I feel OK but have balance problems when standing. Can my balance problems be caused by overdosing? And is there a time frame for when I may feel normal?

    • Hi Steve,

      It could be related to your thyroid dose, but there’s no way to know for sure unless you adjust your dose appropriately. My guess is that it is probably related to something else, however.

  10. Hi Dr. No, absolutely not! I don’t think there’s any amount 9f Synthroid and Cytomel that would ever make me overdosed. If I forget to take a Synthroid, I feel it within hours and I pay hard the next day. It’s not been as severe since the cytomel was added but it’s still a fast reaction. I don’t believe Synthroid stays in my body 5-7 or 35 days.
    Also, my TSH has been under the range .28 and the next month a 7.8. this was before cytomel. After it was less of a swing like .40 to 1.3 (but I feel hypo symptoms and awful when I get close to 1.0). I feel ok – not good, not great just a tad below normal at . 40 and. 28. A 2.0 really has me feeling bad. I had a surgery last year that delayed thyroid maintenance. I ran out of Synthroid for a week but still had cytomel. Then got a refill to hold me over thru my appointment. So 22 days after that week of missing Synthroid, my TSH is. 04 but free T4 and T3 (not free) are smack dab in the middle of the range. I don’t have any symptoms of hypothyroidism not even close.
    I do have questions what causes a person to be absolutely nothing like the classic “symptoms”. For example, metabolism never increased back to normal, the entire time I was hypothyroid at a 2 TSH, even tho I had significant weight gain, fatigue, light headedness, digestive issues, insomnia, anxiety, hair loss, heat intolerance and cold intolerance both, severe allergies, eczema. What causes that? Lots of those symptoms are tagged as hyperthyroidism but I was significantly hypothyroid. Although the treatment hasn’t affected my metabolism at all, my hair loss resolved itself, I no longer need allergy medication, I no longer get severe bronchitis every spring. Using name brand Synthroid stopped the all over muscle quivering I had accepted. There was a slight improvement in really severe fatigue and over the years it improves. In short measures. But why are we told certain symptoms are hypothyroidism and certain symptoms are hyperthyroidism when that’s not true? It causes “normal” people as well as doctors to make incorrect assumptions.

  11. My 85 year old mother has accidentally been overdosing on Levothyroxin for several weeks now and I just discovered it last night when checking her pill organizer. She was increased from 88 to 100 a few weeks ago but I found several of the 88s randomly stuck in the little compartments…so she’s been overdosing here and there. She has horrible symptoms and we’ve spent a lot of time having tests and seeing different doctors the past several weeks. Yesterday was the worst day. She was shaky, confused, had to be helped to stand and walk. She also had bloodwork yesterday which is going to turn out really bad. I don’t know whether to give her a Levothyroxin this morning or not! I’m thinking it might be best to skip it today since she’s obviously overdosed.

    • Hi Becky,

      The treatment is quite easy if her symptoms are truly due to taking too much medication, but in the elderly and in situations like this, you shouldn’t make any changes to her medication without consulting with her physician.

  12. Hi Doctor! I had papillary cell carcinoma of the thyroid 40 years ago followed by a dose of radioactive iodine. I have taken Synthroid ever since and was advised to keep my levels of TSH at the lowest range possible usually about .3 to .4. As the years have gone by with no problems at and have been well until a few years ago when they lowered my level of .125mcg to 6 days / week. Then a few months ago my endocrinologist told me to take it 5 days/ week. I had to have a blood test for other health issues a few days ago and about fainted when my level of TSH registered at 12.1!!!!!! What now? Any thoughts….. faulty lab test, poor Synthroid quality etc., etc., etc.? I am 78 years old and cannot gain any weight and have lost both muscle mass and should be about 125 lbs not 100 lbs!!!

  13. Hi,

    I was recently put on 25mcg of synthroid three months ago and noticed it working and was feeling great. Almost four weeks ago, I had my IUD removed and since then, all hell has broken loose on my body – aching, jittery, tingling, dizzy, nauseous, flush face, tingly thyroid gland on occasion…. it’s a mixed bag.

    I have a follow up apt with my doctor to go over my three month bloodwork but am curious if it’s possible I may not even need synthroid now with the IUD out and my body trying to regulate?!?

    • Hi Cindy,

      It’s always a possibility. You will need to check your labs to make sure. There’s also going to be some dysregulation of your hormones after you stop taking any sort of birth control (assuming your IUD was secreting hormones) which you may be dealing with as well.

  14. Maybe I have a neurological problem that’s developing, but I think it’s too much Synthroid. I feel normal when I wake up in the morning, I take my Synthroid at the same time every morning at wait an hour until I eat breakfast. By breakfast time my muscles get very stiff and I’m having peripheral neuropathy. As the day wears on my symptoms slowly subside. Have I suddenly become over sensitive to Synthroid? I only have my TSH checked, and it’s always within range. Do you have any suggestions? Thank you!

    • Hi Trevor,

      It’s always a possibility but the symptoms you are describing are typically not seen from thyroid medication.

  15. My hypothyroidism (diagnosed over a decade ago) presents itself symptomatically as hyperthyroidism. I’m thin with usually high energy levels. I’m 72 now but I’ve been an athlete all my life. Up until Jan ‘19 I was still running 6 miles a week. Then I started to feel debilitating fatigue and a dull headache. I had a sinus infection at the time so I contributed the fatigue/headache to the infection. Also, I lost 10 pounds taking my 5’6” muscular frame down to 120. All that started the end of December, and I am still often exhausted. I take dogs for an easy walk and come home for a nap. I also experience night sweats and palpitations. Then I started to think about the fact that my Synthroid dosage has been changed three times over the past year. I went from 175 MG to 150 MG. Yesterday my internist changed dosage to 125 mcg . I am searching for answers. Any Advice?

  16. Since my dose was increased from 75 to 88 I’ve had the symptoms described. Was given this medication after a seizure as the test results in the hospital came back “borderline”. When asked why take the meds then her response was I would need it anyway sooner tor later…

    • I feel your pain I was never supposed to be on thyroid meds. Now I’m paying the cost of that now. Trying to wean off of them and be healthy again. 1 1/2 year later. Best of luck. And Dr. Child’s I think stopped responding

  17. Hi, I was recently diagnosed with hyperthyroidism after numerous er and Dr. visits.
    My dose was decreased from 112 mcg to 88 mcg. In the meantime, I was put on propranolol be for rapid pulses that I was having. I will be getting my blood work done in about 5 weeks but my question is how long do I need to continue to take the propranolol? I was told until my thyroid levels are back to normal.

  18. Dr. Child’s – I believe I am on too high a dose. I have had Hashimoto’s for 26 years and my meds have been adjusted up and down over the years. I have recently started have what feels like a pounding heart, palpitations, very overheated when nobody else is, etc.

    My last blood test came back with TSH @ .35L, T4 @ 1.4 ng/dl, T3 @ 2.7 pg/ml

    I have a call into my doctor but feel I need to reduce my dosage immediately. I am on 175mcg and prior to that I was on 150mcg. We have been having trouble finding the sweet spot. With the results above we decided in June to keep on 175mcg but I think now that was the wrong decision. What are your thoughts?

  19. I was on Levi 137mcg and began experiencing heart palpitations, horrible pressure headaches, blurry vision, and shortness of breath. In the ER they told me they thought it was related to my thyroid meds but they couldn’t adjust them. When I got my lab work I saw that my TSH was .01. I had to completely stop my meds for nearly a month. Worst sickness ever. It felt like what I’ve heard illegal drug withdrawals felt like. Eventually started back in 50mcg of Synthroid. Gradually eased back on 112mcg. Three months later TSH was 7.50, increased meds to 112mcg Synthroid. Three and a half months later TSH .064 completely over medicated again. Awful symptoms again off meds and weaning back on for nearly four months again. On 112 mcg and TSH is 8.300. Doctor said cancer markers are good so he is comfortable with leaving me where I am. Three doctors looking into it and no one knows why. Can you offer any studys or information that discuss what causes TSH to keep shooting so low? I am getting no answers just that they suspect I’m taking B vitamins, which I can assure you isn’t the case. I am desperate for some sort of help, my quality of life has diminished greatly.

  20. Dr. Childs…I’ve followed you for years and so appreciate your knowledge and guidance. I had a total thyroidectomy 42 years ago due to cancerous nodules and RAI 4 times over the years. Drs over the years only looked at TSH and T4 and not symptoms. In 2014 I retired and move and needed to find new doctors. Retirement lessened stress and allowed me to exercise at the Y 3 times/week. Although Johns Hopkins surgeon told me to always take Synthroid, I switched to Levothyroxin to lessen cost with new drug plan. By 2019, I’ve gained 15 lbs and no energy to exercise, anxiety, mood swings, constipation, etc. Your info tells me that Levo can cause weight gain. I’ve been to 2 PCPs and 1 Endo in the last year…but, I feel more knowledgeable then they are. Begged to go back on Synthroid (from 88mcg to 100mcg…now 112mcg) and start Liothyronine (5mcg…now 10mcg). Spent March in Florida and went to an Integrative Dr who did extensive lab work and Dutch urine test for adrenals and hormones (ovary removed, breast cancer, divorce – high stress). I’m also addressing my microbiome with probiotics. Due to the Corona virus, I have a telecon 4/15 with the FL doctor. Looking at my labs….TSH is 0.024 (low), T4 7.6, T3 Uptake 30, FT4 1.45, Triiodothyroine 195 (high) and Triiodothronine T3 Free 6.3 (high). This is more thyroid information than I’ve ever seen. I feel good, have more energy and no hair loss. Should I be concerned that I’m over dosed?

  21. I am currently being treated for Hypothyroidism. Last year at this time my TSH was 0.01 ulU/Ml and my Free T4 was 2.35 ng/dl. My endo did not change my medication dosage. I tested again today and my TSH is still 0.01 ulU/Ml and my Free T4 is 2.22 ng/dl. Is this considered acceptable lab levels? I’m trying to decide if I need to switch physicians. I am currently taking Synthroid 200mcg. My TSH could actually be lower than that, it may just be that 0.01 is the lowest my office’s lab will detect. Would levels like this cause long term effects after a year? I’m just concerned damage has already been done. Thanks in advance

  22. Hi I hade 3 years ago thyroidectomy thyroid goitre and I start 125mg Synthroid I don’t feeling good I was keep telling to my dr that I felt third heart palpitation extreme hair fall and he told me he don’t know why I went to my family dr se reduce my dose to 112 than after 6 month 100mg put I still feel heart palpitation and hair fall even the sort hair what is start to grow it’s fall out i really don’t know what to do sud my dose need to be reduced more please help!!:((

  23. My issue is I was put on Synthroid in Jan 2019 25 mcg. Because the obgyn thought I was hypothyroid yet tsh t4 T3 were good. March I was sick yet she told me I was fine. June was in hospital because my doctor gave me HCG for weight lossand ciprofloxacin for infection.
    Endo at hospital told me my thyroid had stopped. From a 2.0 to zero nothing. They cold turkey me off meds saying I never should have been in them. June July aug I was great again .
    Sept I crashed tsh was a 10 . They put me on 25 Synthroid again!!!
    Jan. I got very sick . Since then not been feeling good and extremely heat intolerant and gaining weight and brain fog. and tsh is a 4.0. they took me from 25 to 18 McG. I feel better but I feel floating like I’m not all the way there. Still brain fog. Floating feeling. Is my thyroid fighting to come back.? Our doctors here said they give up. I’m really scared.

  24. Hello Dr. Childs,
    I have some much needed questions to be answered. I have been diagnosed with hypothyroidism 30 years ago and I am now 60. I have been on Levothyroxine for that long. When I was diagnosed I was very sick. Had many bad symptoms. TSH was 7 or 8. My Gyno started me at .125 and stayed on that for many years until I started feeling the effects of too much meds. Menopause set in I was dropped to .88 then .75 then back to .88. Well I decided to ask my ears nose and throat doctor can I try the name brand Synthroid. Well I have been on it for 35 days and have developed jitters heart palpitations asthma like feeling tired and flushes. Is is because of the switch? My TSH was 1.64 before the switch to name brand. Hope you can answer some concerns I have.

  25. Good Afternoon, Doctor, 8/10/20
    I was on .88mcg of Levothyroxine for ten years. Within the month I changed my Primary Care Doctor. Her Lab tech drew blood and it came back 44.4 Thyroid level. She increased my meds to 100mcg. Within one day I developed explosive , unprdictable diahrheoa and great fatigue(not to mention the anxiety associated with being afraid to leave the house!). I continue to have this diahrheoa. I do drink a lot of water, eat very little because my stomach does not feel right. I also have gone through heart issues with my Cardiologist. He increased my Rhythmol to 325mg 3 times a day to FINALLY get the Atrium
    to do its job and get the upper and lower chambers working properly together. What a time I have had! Please comment on this.

  26. Hello Dr.
    Was wondering why my TSH fluctuates so much on the same dose, 88mcg. Over the last several years has been 21 -0.7 and a boatload of others in between; 17, 2, 5,9,3…. During the summers I always have heat intolerance. Severe sweating and shaking. Racing heart. Feeling very hyper and shaky. T3 and T4 normal. Thanks very much for the recommendation.

  27. Hello Dr.

    I have been on levothyroxine for many years and my dose was 100mcg for years. About 6 or so years ago it was decreased to 75mcg. I had been exercising and eating well for years. I noticed my resting heart rate was extremely low and I had increased palpitations. My TSH was normal but at the very high end. T4 in range and T 3 low. My Endo upped my dose to 88, with a couple of weeks I felt great, However after a test it dropped to .26. So she suggested I keep the dose but once a week take half a tablet. That had worked for me. A couple of months ago I tested and my TSH was 3.99. I decided to take the full dose rather than the half dose each week. However for the past few weeks I have been experiencing palpitations, I went to dr. as I was enough to concern me. Had an EKG which didn’t detect any palpsDid bloods again and all are in normal range, TSH 0.77 T4 1.2 and T3 89 (Which I might add had been low and out of range for years).

    Could that extra half tablet just be too much for me? Even though the tests show normal. If I reduce a half tablet each week when should I notice a reduction in symptoms?

  28. Hi I am 72 year old male 5′ 10 180 lbs. Very fit and active, cycling gardening and still working. Enjoying life even in pandemic! No underlying health problems problems (at all)
    I have been taking 225 mcg levothyroxine for many years. Took two years to be diagnosed and put on 100, then six months later 150, then reluctantly 9By GP) 200. Each time I felt so much better, but it tailed off with time. So a young locum GP said it would not hurt going to 225 and see what happens. I did go to 250, but felt no difference, so dropped back. But I am just wondering if, because of increasing age, I ought to drop back to 200?

  29. As a patient for 15 years I have to disagree with one thing in this article. You can have toxicity and exhibit all of the symptoms above with a normal T3 and T4 and a TSH that is hypo. I know this because I’m experiencing it for the second time this month and a third time in total. I don’t know how my body could have become so sensitive but luckily my endo is lowering my dose because my PCP said my labs were normal and refused. You have to treat the patient not just the labs. If a patient is exhibiting all the outward symptoms of toxicity you have to look beyond the lab results.

    • Hi Rebecca,

      I completely agree. I’m not sure where you read in the article that this can’t happen but it certainly can. Some patients are sensitive to even small doses of thyroid medication, regardless of what their lab tests show.

  30. Hello, I have a low thyroid. About 15 yrs. Ago when I was diagnosed I was put on levothyroxine 7mcg. This past 2 yrs. I was having the symptoms of extreme hair loss. Sweating as if in a sauna, very dry skin, weight gain. Very tired. I had blood work done this yr. 2022 and they decided to move the mcg too 50mcg. It really worked great. It’s been 4 months now. But recently, I’m still feeling very hot. And a tiny bit of hair loss. I’ve been feeling antsy and tired. I do get heart flutters once in a great while. Should I tell the Dr. To have it lowered some more or what. Don’t know what to do.

    • Hi Mary,

      It’s always best to test your thyroid labs before making changes to your thyroid medication. The first step would be to make an appointment to do just that!

      It’s also possible that other conditions, such as menopause, are contributing to your symptoms.

  31. Hi the pharmacy had been giving me 125mcg and my normal dose is 75mcg. My tsh levels had dropped in some areas but even though it was a dramatic drop compared to my normal levels I was still within normal range. I have mental health issues and I noticed that since taking the overdose amount for the past month my depression and suicidality increased until they were at a level I’ve never experienced before with my mental health. I’ve also lost weight and was flushing and having panic attacks I didn’t have before. My question is are these overdose symptoms normal for some people? And how long until I can start feeling better? I’m back on 75mcg.

    • Hi Danielle,

      Some of those symptoms are normal-ish but others are not. It will take about 2-4 weeks for the extra dose of levothyroxine to clear from your system but the symptoms may linger for longer than that.

  32. Hello, I have had Hashimoto’s since shortly after giving birth to my 1st child, who is now 21; Should also mention I am a Type 1 diabetic. Have kept my TSH around 3.0-3.2 for years on 75mcg, until 3 months ago, and then it came back at 35.8!!! So, Doc increased me to 125mcg and I retested 8 weeks later, and my TSH is only down to 17.4!! He says he thinks my thyroid is completely shutting down?? Just went up to 150mcg last week, and I’m only 168 pounds. Thoughts?


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