Thyroid Supplement Dangers

“Thyroid support” supplements that can be purchased over the counter carry many serious side effects that most patients do not know about, according new research from the Mayo Clinic presented in Nov, 2011.  Here our overview of the use of supplements in thyroid disease

The supplements promise to improve thyroid function, jump-start weight loss, and reduce fatigue. Unfortunately, the ingredient can elevate heart rates, cause arrhythmia, induce nervousness, and create diarrhea, said senior investigator Victor Bernet, MD, who presented the findings October 27, 2011, at the American Thyroid Association annual meeting.


Triiodothyronine (T3) and thyroxine (T4) are thyroid hormones which can be made in pill forms which are regulated by the FDA. These pills and intended for use only in prescriptions levothyroxine (Synthroid, Levoxyl) and liothyronin (Cytomel). Over the counter supplements can contain these T3 and T4 hormones which are derived largely from dehydrated animal thyroids. Nine of the 10 over-the-counter supplements (OTC) contained these hormones according to Dr. Bernet and colleagues. Only  5 of the 10 products tested listed animal thyroid gland as an ingredient. Amounts of T3 and T4 in the hormone-containing pills varied widely, with some delivering a dose of up to twice the daily requirement for a healthy adult, the researchers noted. The findings indicate the need for stricter regulation of OTC thyroid support supplements, according to Dr. Bernet.  

 “These hormones have effects throughout the body, which is why they are controlled,” he said in a news release. The effects of thyroid hormone are well known. 

These thyroid supplements are widely marketed as a remedy for symptoms associated with thyroid disorders.  Because these symptoms (unexplained weight gain or lack of energy) are so common, patients may think it’s safer to choose an OTC supplement rather than consult with a physician.

Taking these supplement pills without a physician’s guidance is dangerous and likely not improve the symptoms it was intended to treat, said Dr. Bernet, who also serves as chairman of the American Thyroid Association’s public health committee. He began studying thyroid support supplements after physicians reported cases of abnormal thyroid test results in patients who took them. 

In addition to the need for better regulatory oversight, Dr. Bernet said there is a need to educate patients about the drugs’ risks—which likely outweigh any potential benefits from taking them.

 "The amount of thyroid hormone a normal person would have to take to lose weight would be dangerously high and there is no evidence that use of thyroid hormone effectively treats fatigue when used in people without actual hypothyroidism," he said.