Synthroid: 5 Reasons it Isn’t Working for You (and how to fix it)

Synthroid: 5 Reasons it isn’t working for you

Synthroid Can Work (But not always)


Many people are quick to jump on the bandwagon and make statements like Synthroid or levothyroxine simply don’t work. 

But is that actually true?

Not entirely. In fact, Synthroid CAN work for a lot of people. 

But it is true that there are other options that may be BETTER for many of you (we will discuss these options below). 

But before you jump ship on your Synthroid and try to switch to another medication there are MANY things that you should know. 

These things can potentially help your Synthroid work better in your body and actually help you to feel better. 

If you are experiencing PERSISTENT symptoms of hypothyroidism DESPITE having so-called normal thyroid lab tests or taking Synthroid then pay close attention to these factors because they may explain your situation. 

5 Reasons Why Synthroid Isn’t Working for You

If you are taking Synthroid and it isn’t working well for you then make sure that you take a look at these COMMON issues. 

And remember:

These problems ALSO exist for those taking levothyroxine (they are NOT exclusive to Synthroid only). 


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#1. Your Dose. 

The first place you should look is directly at your dose. 

In other words, how much medication are you actually taking? 

Synthroid ONLY works if you are taking enough of it.

And this should make sense if you think about how thyroid medication works. 

If you have hypothyroidism or a sluggish thyroid then you are taking thyroid medication to supplement the difference between what your body needs and what your body is able to create. 

But there’s one big problem with how most doctors dose Synthroid. 

And that is that they tend to UNDERDOSE the medication


Because they focus primarily on the measure of TSH (or thyroid-stimulating hormone). 

And TSH is a poor marker for the thyroid status in the rest of your body due to the difference in deiodinase enzymes found in your pituitary gland (the gland that produces TSH). 

What you want to look at instead are your free thyroid hormone levels (including free T3 and free T4). 

If your free T3 and free T4 are normal (along with a healthy TSH) then there is a good chance you are taking enough medication. 

But you will find that MANY of you reading this have a normal TSH but low free thyroid hormones and this indicates that your dose is insufficient. 

The good news is that this problem can be remedied by simply increasing your dose or taking more thyroid medication. 

#2. Absorption problems. 

Another important problem that many hypothyroid patients face is absorption issues. 

It’s not enough to simply take your Synthroid by mouth. 

No, not even close. 

Once you ingest Synthroid it must be absorbed, then it must be converted, then it must activate your cells, and so on. 

And absorption is the FIRST step in this process and it is an issue for many people who take Synthroid and levothyroxine

What do I mean?

I’m trying to say that many people taking Synthroid by mouth don’t actually get it into their bodies because it doesn’t get absorbed. 

Synthroid is a funny medication in that it is exquisitely sensitive to certain factors found inside your gut. 

If any of these factors exist then they won’t be absorbed. 

The primary driver of these issues is gut-related issues such as irritable bowel syndrome, acid reflux, low stomach acid, constipation, diarrhea, gas, bloating, and so on. 

Do any of these sound familiar?

If they are present then you will probably have issues with Synthroid absorption. 

You can fight this issue by treating those gut problems to enhance the absorption of your medication. 

#3. Conversion issues. 

Next on the list is something known as peripheral thyroid conversion. 

And this refers to the activation of your thyroid hormone. 

You see, Synthroid contains the T4 thyroid medication. 

But T4 is not active by itself and in order for it to be activated, it must be converted into T3 (triiodothyronine). 

If this process doesn’t occur then your Synthroid will be ineffective. 

Your doctor (endocrinologist) knows this but they assume that your body has no problems with this conversion process. 

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And this is where the problems start. 

We know from certain studies that up to 20% of the population, due to simple genetics (1), does NOT convert thyroid hormone as effectively as other people. 

This means that up to 20% of you taking Synthroid may not be doing this conversion very well! 

There are, of course, many other factors that can influence this conversion process. 

Things like being overweight, having inflammation in your body, liver damage, and so on, can all limit T4 to T3 conversion as well

This is a big problem and it leads us to #4 which is…

#4. It’s just the wrong medication. 

While I want you to do whatever you can to try and get your medication to work for you there may come a time when you have to say that Synthroid just isn’t ideal for your body. 

But don’t let this discourage you. 

There are MANY different types of thyroid medications available. 

Your doctor may only be aware of Synthroid and levothyroxine but there are at least 10+ other thyroid medications to choose from. 

So if you find that Synthroid isn’t working for you then you can simply switch to another brand or type of thyroid medication and it may actually help you feel better. 

Other thyroid medications include:

And many others. 

The key here is to first give Synthroid an honest shot (use the strategies listed here to see if it can work for you) FIRST. 

If you can’t find a significant improvement over the course of 6-12 months then it may be time to seriously consider just switching to a different thyroid medication

#5. You’re taking it wrong. 

Lastly is the fact that you may just be taking your medication incorrectly!

As I mentioned previously if Synthroid is not taken perfectly then there is a good chance that it won’t actually be absorbed into your body. 

This is why your doctor (and probably pharmacist) told you to take your thyroid medication FIRST thing in the morning and to avoid taking any food or supplements for at least 4 hours after you take it. 

Sound familiar?

Well, the reason they say this is because they KNOW that many different things can limit how well it is absorbed. 

But when has your doctor ever asked you if you are taking it correctly?

Probably never, even if you are feeling terrible. 

This shows that there seems to be a disconnect between what doctors know and how they practice. 

Ok, with that in mind, let’s actually talk about how you should be taking your medication to ensure that absorption is NOT an issue. 

When taking your thyroid medication consider these important factors:

  • When you take your medication matters – Many people take their thyroid medication FIRST thing in the morning but this isn’t the only time of day you can take your medication. In fact, newer studies have shown that it may be BETTER to take your medication at night (2). Your intestinal tract is SLOWER at night which means that it stays in your gut longer which allows for more absorption
  • Are you taking your Synthroid with coffee? Coffee will severely limit the absorption of your thyroid medication. How many of you listening to this take your medication with your morning cup of coffee and your breakfast? Doing this is a recipe for decreased absorption. Coffee SPEEDS UP the intestinal tract (the opposite of what you want) which is why it can cause bowel movements in the morning. 
  • Are you taking your Synthroid with food? Food, with the exception of water, has been shown in medical research (3) to disrupt Synthroid absorption! And this applies to all types of thyroid medications including levothyroxine. The only exception is a thyroid medication known as Tirosint. 
  • Are you taking your Synthroid with supplements? Specifically, iron or calcium? Iron and calcium (4) are notorious for BINDING to and INACTIVATING the active component of thyroid hormone! They aren’t the only supplements that do this either. This is why your doctor should ensure that you aren’t taking your Synthroid within 4 hours of either iron or calcium. 


What I want you to realize is that there are many things that YOU can do to potentially help improve how your body processes and utilizes Synthroid in your body. 

If you are experiencing weight gain, fatigue, hair loss, and so on, despite taking Synthroid then you should take a look at THESE factors. 

Many of you reading this will be able to find some improvement just by making these small changes. 

And if you can’t find improvement then, yes, it may be time to switch to a new thyroid medication entirely. 

But do your best to at least give it a shot for a few months. 

Now I want to hear from you:

Are you using Synthroid?

Is it working for you? Why or why not?

Have you tried any of the therapies listed in this article?

If so, which one, and did it work for you?

Leave your experience and/or questions in the comments below to keep the conversation going! 





5 reasons synthroid isn't working for you

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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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