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Supplements You Shouldn’t Take With Thyroid Medication


Article Summary

  • Get a quick reminder of what the thyroid is, what it does, and why it’s so important.
  • Learn about the reasons someone might need thyroid medication.
  • Find out which supplements you shouldn’t take if you’re on thyroid medication.

The thyroid is one of those parts of the human body we often forget about. It’s a gland that lives along the windpipe below your Adam’s apple. Even though we don’t think about it often, your thyroid is actually incredibly important. This small gland helps to regulate hormones throughout your entire body. It has a notable influence on your growth and development when you’re younger, your metabolism throughout your life, and even your body temperature.

There are a number of problems that can affect your thyroid. You might grow nodules that interfere with its function. You can get inflammation (thyroiditis), goiters (swelling), Graves disease (an autoimmune disorder), or even cancer. Two of the most common disorders include hyperthyroidism and hypothyroidism. 

  • Hyperthyroidism means the body overproduces hormones. It’s often called an overactive thyroid and is typically caused by nodules or Graves disease.
  • Hypothyroidism means the body has an underactive thyroid, resulting in low hormone production. It is most often the result of damage from an autoimmune disease.  

Even though this gland is rarely thought about, more than 12% of the U.S. population will develop a thyroid condition in their lifetime. And recently updated studies have shown that thyroid disease is far more widespread than doctors initially thought, indicating a surprising 3 million people may have an undiagnosed thyroid condition. 

Luckily, some people can manage their thyroid challenges with a healthy lifestyle, such as diet, high-quality supplements, and exercise. For most people, however, managing such a condition involves taking medications. 

You already know that supplements can be a great way to ensure your optimal health. Taking the right supplements can help you fight food cravings, fill in dietary gaps, support brain health, gut health, bone health, metabolic function, and so much more.

However, some supplements can react with thyroid medications, leaving you with the frustration of coping with a variety of unsavory, even detrimental complications. 

To help you avoid negative interactions with your thyroid medication, we have listed five supplements that you shouldn’t take while you are on thyroid medication.

Calcium supplements and thyroid medication

Not everyone realizes this, but there are a few different types of calcium compounds. However, so far, only two types are used in supplements: calcium carbonate, which contains 40% calcium, and calcium citrate, which has 21% calcium.

Both types of calcium have a similar impact on how the body absorbs thyroid medication. One particular study showed that calcium supplements could interfere with your body’s ability to absorb thyroid hormone replacement medications such as levothyroxine and other thyroid extract supplements. The interference tends to occur when you take both of them at the same time. 

Fortunately, this absorption issue can be avoided by taking a few steps:

  • Taking your thyroid medication on an empty stomach to allow your body to absorb it properly
  • Taking it shortly after your wake up, at least an hour before you eat breakfast or have your cup of coffee
  • Waiting at least four hours before consuming a calcium supplement

Pro tip: if you plan to take your thyroid medication at night, be sure to do so at least four hours after taking your calcium supplement so the two don’t interfere with each other.

Iron supplements and thyroid medication

Getting sufficient amounts of iron is crucial for several reasons. Most importantly, it plays a vital role in the transportation of oxygen throughout the body. Think about the effects of an oxygen-starved brain. Feeling tired, dizzy, cold, and getting headaches can be symptoms of anemia, an iron deficiency

Those suffering from Hashimoto’s disease, an autoimmune disorder that can cause hypothyroidism, have to be careful that they are getting enough iron. This is because iron is not only crucial to getting oxygen where it needs to go, but iron is also essential to a functioning thyroid.

However, like calcium, iron can interfere with the body’s ability to absorb thyroid medication. And similar to calcium, there are different types of iron. Some are harder on the digestive system than others and can cause constipation. 

Only a doctor can tell you to take an iron supplement, but if you do need to supplement your iron intake, as many with hypothyroidism do, choose a plant-based iron supplement. A non-heme iron supplement (plant-based) can be taken twice daily along with vitamin C to enhance absorption.

Thyroid supplements and thyroid medication

Some supplements are specifically marketed to those who have thyroid conditions. Of course, if your doctor directs you to take thyroid supplements as part of your medical regimen, then it is considered a safe component of your health and lifestyle.

However, taking thyroid supplements without the recommendation of your doctor can create several problems. One of the most significant drawbacks of thyroid supplements is that they may contain hormones that can interfere with your thyroid and medication.

You wouldn’t know if these supplements have hormones from the label, but a 2013 study discovered nine out of ten supplements marketed for those concerned about thyroid health actually contained synthetic and bovine hormones. These were hormones that do not naturally occur in plant-based ingredients, which means they would have been intentionally added to the supplement.

Because there is no way to measure the hormones contained in these supplements, and thyroid management requires precise and predictable hormone levels, it is not recommended that you take thyroid supplements without the explicit direction of your doctor.

Biotin supplements and thyroid medication

Biotin is a common supplement taken to support healthy hair, skin, and nails. Also called vitamin B7, most over-the-counter supplements contain high doses from 5,000 to 100,000 micrograms. However, 30 micrograms is considered adequate. 

Luckily, biotin is water-soluble, so the likelihood of overdosing is extremely low. You would need a sustained 200,000 micrograms to produce symptoms of toxicity. 

The problem with biotin when it comes to your thyroid is that it can interfere with thyroid blood tests. It actually mimics the results of graves’ disease, an autoimmune disorder that causes hyperthyroidism, or overactive thyroid. 

Double-check with your physician before taking biotin if you are on thyroid medication. And it’s generally advised that you stop taking all biotin supplements at least two days before your next TSH blood test, to ensure accurate results. 

Ashwagandha supplements and thyroid medication

Ashwagandha is an herbal plant, also known as Indian ginseng. There is increasingly widespread use of ashwagandha as a supplement because it’s an adaptogen, which means it’s used for a variety of conditions including bipolar disorder, weight management, arthritis, stress management, and neurodegenerative disorders, and a great deal more

While early studies have shown favorable results when it comes to this herbal supplementation and thyroid conditions, there are just a few noteworthy points that should be mentioned when thinking about taking it with thyroid medication.

First, this herbal supplement does not contain hormones but can have a boosting effect on your hormone levels. For those with hyperthyroidism, which is an overactive thyroid, increasing thyroid activity with ashwagandha may exacerbate the problem. Ashwagandha may actually work against the results your thyroid medication is trying to achieve if you have hyperthyroidism.

Second, preliminary evidence is suggesting that ashwagandha may help hypothyroidism, leading to an increase in the number of people either treating their condition or supplementing their medication with ashwagandha.

Final thoughts

Before taking any supplements, it’s highly recommended to consult your doctor first. However, if your doctor doesn’t have much knowledge regarding these supplements, you can talk to a naturopathic doctor instead. Just make sure to inform your physician who’s responsible for treating your thyroid disease beforehand.

If you’re concerned that the supplement you’re taking may have an interaction with your thyroid medication, we recommend checking out the Interaction Checker to understand the potential medically documented drug interactions better.

Some supplements may interfere with your thyroid medications. Ashwagandha and hyperthyroidism, for example, or thyroid supplements and medications, may cause interference. Some supplements just need to be effectively managed, such as iron and calcium. And supplements such as biotin need to be managed to avoid false positives on thyroid blood tests.

As long as you do your research, work with your physician, and take high-quality supplements when you do choose to add them to your health regimen, you’ll be able to reduce symptoms, increase wellbeing, and enjoy a long and healthy life.

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