Signs and Symptoms of Selenium Toxicity

Signs and Symptoms of Selenium Toxicity – Are you Taking Too Much?

Serious Selenium Toxicity is Rare but Minor Excess Is More Common Than you Think

Selenium is one of the most important micronutrients in your body when it comes to your thyroid. 

Selenium also plays an important role in regulating enzymes that help protect your cells from free radicals. 

These enzymes are known as selenium-dependent enzymes (1) and they are important for many cellular pathways in your body. 

To take matters a step further, it's not uncommon for many people to suffer from low-grade selenium deficiency

Minor deficiency is common due to rampant due to modern intensive agricultural farming methods (2) which have stripped the soil of its nutrients. 

Today this soil only contains a fraction of what it used to. 

And this soil depletion has real consequences for people like you and me when we consume fruits and vegetables. 

For these important reasons, selenium is often included in many over the counter supplements. 

And it is the minor toxicity that can occur from these supplements that I want to focus on today. 

You see, it's actually quite rare that humans suffer from overt selenium toxicity. 

But it's not uncommon for people to accidentally take too much in supplement form as they attempt to replace low levels caused by issues like soil depletion. 

And the side effects of low-grade selenium toxicity, or selenium overdose, can be difficult to identify and may actually mimic some of the same side effects as selenium deficiency. 

Another group of patients at risk for selenium toxicity is thyroid patients. 

These patients tend to take higher doses than selenium in an attempt to bring down thyroid antibodies in disease such as Hashimoto's thyroiditis

And while there is evidence that this can be effective, it's also potentially harmful if the wrong dose is used. 

Let's break it down. Today you will learn:

  • The early warning signs of selenium toxicity
  • Warning signs that you are taking too much selenium in supplement form
  • More serious side effects of selenium toxicity (these are rare)
  • How to know if you are taking the right amount of selenium and what dose you should be taking
  • And more

Let's jump in...

Minor Problems & Symptoms (Usually from taking too much in supplement form)

While serious selenium toxicity is incredibly rare, minor selenium toxicity is not all that common. 

Selenium is found in MANY over the counter supplements including multivitamins, thyroid support supplements, adrenal support supplements, women's daily vitamins, and specific selenium only supplements. 

If you aren't paying attention, or if you are someone who is simply sensitive to selenium, it's possible that you may be taking too much. 

It's not too much in the sense that it will cause you serious problems but it could definitely be enough to prevent you from feeling at 100%. 

The following signs may indicate that you need to back off on your selenium dose: 

#1. Hair Loss - Selenium deficiency can also cause hair loss which means many people with hair loss use selenium. Just be sure that your dose isn't too high or you may cause the same problem. 

#2. Brittle Nails - Selenium toxicity can cause changes to your nail beds including discoloration in your nails. 

#3. Fatigue - Fatigue and low energy may stem from thyroid problems which excess selenium may exacerbate. 

#4. Gastrointestinal (stomach) problems - This may include having an upset stomach, feeling minor stomach pains, changes in bowel movements, and so on. 

#5. Joint Pain

#6. Nausea - Nausea that sticks with you throughout the day may be an indication your selenium level is too high. 

These minor symptoms should completely fade within 2-3 months once you stop taking selenium. 

Serious problems that indicate you have Selenium Poisoning

Serious and life-threatening selenium toxicity can and does occur but is incredibly rare among humans. 

It's much more common in livestock because the primary source of selenium depends on soil concentrations. 

If animals are consuming soil which is heavily concentrated in selenium then they may start to experience signs of excess. 

And these symptoms can also occur in adults, though it's incredibly rare that they occur. 

Most of the time, selenium excess is typically only minor and comes from excessive use of over the counter supplements. 

And most people stop using the offending agent when they start to feel the minor issues listed above. 

Having said that, let's at least mention some of the more serious side effects: 

#7. Neurological problems

#8. Paralysis

#9. Selenosis

What to do If you Experience These Signs?

The good news is that there isn't much you need to do to "treat" the problem as it will take care of itself. 

Any extra selenium is typically eliminated from the body within 1-2 days after being consumed, provided your organs are functioning at 100%. 

But, if you do experience the warning signs of excess selenium then you should take steps to try and find the source of selenium exposure. 

This is most likely in whatever supplements you are taking but it could also be from the food you are eating or another environmental source.  

How Much Selenium Should you Take Each Day?

Well, it depends on who you ask...

The RDA for selenium is somewhere around the 40-55mcg range depending on your age (3). 

But the problem with the RDA is that it's set for 97% of the population (which leaves out a small percentage of people), the RDA is set for only the minimum amount necessary to avoid deficiency, and it doesn't take into account conditions where taking more may actually be beneficial. 

There's real evidence to suggest that using the RDA is not sufficient for most people, and while it may stave off overt deficiency it's not enough for people to thrive. 

Because of these known issues, other organizations and physicians have recommended higher doses than the 40-55mcg range. 

And while these doses are better at helping people feel better and improving symptoms, they also run a slight risk that you may take too much. 

Daily selenium intake in the 400mcg to 600mcg range has been recommended in many circles and many patients have had great success using these doses. 

In fact, studies have shown that humans can tolerate 600mcg per day for long periods of time without any issue. 

Even though the studies have shown this, I have personally seen people experience issues when consuming 600mcg per day. 

My recommendation is to stick to the 100mcg to 200mcg per day range. 

This ensures that you are supplementing with a sufficient amount to meet your body's requirements but also not too much that you won't tip yourself over the edge with selenium found in your diet. 

I should point out, though, that some people see improvements in conditions like Hashimoto's thyroiditis at higher doses. 

How to Avoid Selenium Toxicity

The best way to avoid selenium toxicity is to be vigilant about the over the counter supplements that you are taking day to day. 

If you are otherwise healthy, then you should always try to get as much selenium as you can from your diet. 

Selenium rich sources of food include:

  • Brazil nuts
  • Fish
  • Ham
  • Pork
  • Beef
  • Chicken
  • Eggs
  • Brown rice
  • Oatmeal
  • Spinach
  • Bananas

If you are healthy then you may be able to get all of the selenium that you need from these sources. 

When possible, remember to try and consume organic versions of these foods as the nutrient contents are likely to be much higher (4). 

If you have a medical condition in which taking excess selenium may be beneficial, then pay close attention to how much you are taking in your supplement form and how much you may be getting from your foods. 

As long as you supplement in a low dose, in the range of 100mcg to 200mcg per day, you should not run into any issues of selenium toxicity even if you are also eating organic healthy foods high in selenium. 

People typically don't run into issues until they hit that 600mcg per day or higher dose. 

Now I want to hear from you:

Do you think that you are taking too much selenium?

Do you have any of the signs or symptoms listed above?

How much selenium are you taking each day?

Which symptoms or side effects are you experiencing?

Leave your questions or comments below! 

References (Click to Expand)

warnings signs you are taking too much selenium

Dr. Westin Childs

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 45,000+ people have used them over the last 4.5 years. You can read more about my own personal health journey and why I am so passionate about what I do here.

15 thoughts on “Signs and Symptoms of Selenium Toxicity – Are you Taking Too Much?”

  1. I have noticed my nail beds are yellow and I don’t wear polish. I did have a fungus that I took a prescribed 7 day polish for but no longer use it. I am wondering if it is the daily 200 mcg Selenium. My teeth are turning yellow too Your thoughts?

  2. I got my labs today. High range is about 400 and I’m at 675. I quit taking it in august. I have stomach issues daily. Starting the feel like I have dementia. Is there anything I can do to bring my number down?

    • Hi Janet, are you feeling better now and if so how long dud it take ? I was taking a potassium supplement and after months of feeling so ill i discovered in the small print it contained selenium. I stopped supplement but 12 weeks on i still feel awful. All known symptoms and an awful metallic taste in my mouth. I hope you are better now and i look forward to a reply. Best wishes Paula from UK

  3. Dr. Childs – Is there a blood test that measures amount of selenium in as person’s body ?
    I have HAIR LOSS and FATIGUE . so, how do I know if have selenium DEFICIENCY of TOXICITY ?

    • Hi Karen,

      Unfortunately, very few nutrient tests are accurate because they typically test the serum instead of the cells which are what matter.

  4. Hi Dr Childs, I love following you & all your knowledge about the thyroid. I don’t take extra selenium, after reading your article, I’m glad I don’t! I found out about a year an a half ago that I have Hashimoto,s. I have taken Levothyroxin for 20+ years or Synthyroid….from 1.25 mg and all in between now I take .75 with a half a tablet one day a week. My labs recently were TSH .48, free T3 3.2, free T4 .89 . Back in late 2019 my Rheumatoid Factor 102, CCP Result positive, CCP Antibody 500, TPO Antibody 122…. since then I have been on Euthyrox .88 then Unithyroid .88 now Levothyroxin Sodium .75… my question is ( I know they are different forms of Levothyroxin) what makes them different? I have gut issues, dry skin, thin hair the list can go on. I’m 73 and 5 ft 1/2 in and weigh 142… I also have bloated tummy and can’t seem to lose weight. I drop 4-5 lbs and then gain it back… I’m also Diabetic A1c 5.8 take 500mg Metformin..

  5. There are a couple of scientific studies that suggest that even 200 ug/d is too much for some people. That dosage seems to have contributed to cognitive problems for my wife. 100 ug/d should be sufficient for anybody. 600 ug/d might be a short term medical treatment, but would be insane as a supplement.

  6. Hi Dr,
    Would ringing in the ears be a possible symptom of too much Selenium?
    I take 200 mcg of L-selenomethionine a day. vital signs stable, weight is 104 pounds.
    Really appreciate your knowledge!

  7. This is terrifying. I’ve discovered Brazil nuts a month ago and because they are low carb I’ve eaten 30 nuts daily even more. For At least a month. Garlic breath and regularity for sure are symptoms. Please help me how to reverse any damage! They are in trash but what can I do in meantime if anything? Wait it out?

  8. Hi Dr. Child’s,
    I knew you would have the answer for this . My selenium RBC was slightly elevated 323 (range 120-300). I had prob had the gastro symptoms for a month with nausea all day but didn’t correlate it with the selenium . I only supplement about 150-200mcg/day but I had been consuming oatmeal daily + fish and shrimp. I also have the MTHFR genetic mutation which I don’t know if that makes a difference . Can excess selenium also cause lightheadedness and vertigo? I had to go ER for vertigo and all they found was high free t3 (4.1 , which is top of the range )and the selenium. Also, how fast can this exit the body? I had been feeling great and my Hashimoto’s antibodies are nearly in remission but I’m feeling pretty cruddy with this selenium business . Thanks for your help

    • Hi Kim,

      Excess selenium typically doesn’t cause those symptoms but it’s always possible. If you stop taking selenium it should be out of your body fairly quickly, within days.

  9. Hi

    I just accidentally took like 50 drops rather than 4 of my Selenium making that about 3000 mcg of Selenium I would guess. Will I have toxicity or die? Or serious side effects from one overdose?


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