The thyroid is a delicate yet highly integrated system. So much so that even minor changes in thyroid function can cascade into a wide range of health issues.
Many factors influence thyroid function including toxin exposure, diet, and sleep quality. Another often overlooked influencer of thyroid function is the use of certain medications. There are many commonly used medications that can seriously disrupt thyroid function. Having a strong understanding of the thyroid and being familiar with medications that may negatively affect its functionality is an essential part of protecting wellness.
What is the Thyroid Gland?
The thyroid is a small butterfly-shaped structure located in the front of the neck. This gland is responsible for producing various hormones that influence critical areas of wellness including metabolic activity, immune function, and neurological processes. Dysregulation of thyroid function can result in a wide array of symptoms and may even encourage other illness. A common source of thyroidal disruption is the use of certain medications.
Medications that May Harm the Thyroid
Medicines provide an answer to many difficult-to-resolve conditions. However, in some cases these answers come with unwanted side effects that can contribute to other health problems. Some medications, although effective at treating a range of serious health issues, may contribute to thyroid dysfunction and disease. Being aware of these thyroid-disrupting medications allows you to better protect its function and your overall wellness.
Accutane is a derivative of vitamin A that helps to reduce the amount of oil released by glands in the skin. Many concerns have been raised regarding the influence of Accutane regarding thyroid function. Multiple studies show a possible connection between Accutane usage and thyroiditis, autoimmune disease, and significant increases in TSH values. However, more research is required to confirm the negative influence of Accutane on thyroid function.
Accutane is most often used to treat serious skin issues such as cystic acne. Brand names of Accutane include Absorcia, Myorisan, Amnesteem, Claravis, Roaccutane, and Zenatane. The generic form is called isotretinoin or alternatively 13-cis retinoic acid. Known side effects include but are not limited to birth defects, mood disorders, and digestive problems.
The thyroid requires iodine to function properly. However, an excess of iodine can contribute to thyroid issues. The American Thyroid Association recommends that supplemental doses of iodine stay under 500 mcg per day. They also warn that intake greater than 1100 mcg per day can induce thyroid dysfunction. Furthermore, studies show that increased iodine levels may encourage premature cell death and damage to thyroid tissues. Damaged thyroid cells can trigger an unhealthy immune response resulting in an autoimmune thyroid disease called Hashimoto’s.
Iodine supplementation may be recommended when treating certain forms of thyroid dysfunction, iodine deficiency, radiation exposure, and leg ulcers. Iodine is found in many food sources but there is little risk of excessive iodine intake unless actively supplementing with iodine.
Amiodarone contains a high volume of iodine which can easily accumulate in and damage the thyroid. Studies show that use of amiodarone can result in an overload of 50-100 times healthy daily intake of iodine. Additionally, Amiodarone may induce hyperthyroid states.
Amiodarone induced hyperthyroidism typically manifests in two different ways:
- Type 1 is similar to Graves’ disease in that it increases thyroid antibody count
- Type 2 causes thyroid toxicity resulting in excessive release of thyroid hormone
Both forms excessively accelerate thyroid activity, which can trigger a wide range of bodily dysfunction.
Amiodarone is used as an anti-arrhythmic to treat various heart conditions. The drug has many known side effects meaning it is most often used as a last resort.
Oral Birth Control
Most forms of oral birth control are highly estrogenic which may increase TSH values thereby dysregulating thyroid hormone synthesis. Birth control can also increase the amount of thyroxine-binding globulin (TBG) in the system. This causes thyroid hormone to more aggressively bond to one another, which can limit its availability for use in the body. Additionally, birth control can deplete nutrients such as selenium, zinc, and tyrosine which are required for healthy thyroid function.
Oral birth control medications are commonly prescribed to treat acne, menstrual cramps, PMS, endometriosis, POI, and PCOS. In addition to potentially harming thyroid function, estrogenic birth control medications can increase the risk for blood clots, strokes, and osteoporosis.
Studies show that greater exposure to fluoride can induce functional irregularities in the thyroid gland. Additionally, fluoride may impede TSH release thereby limiting thyroid hormone production. A lack of thyroid hormone is a defining trait of hypothyroidism. Furthermore, research suggests that fluoride may induce thyroid inflammation and cell death. This further encourages the development of autoimmune thyroid disease.
Fluoride is included in toothpaste, used in dental treatments, and is even incorporated into our water supply. Many medications including but not limited to antacids, appetite suppressants, antibiotics, anesthetics, antihistamines, and arthritis medications frequently include fluoride.
Although interferon therapies have proven to be beneficial for treating many challenging illnesses, studies suggest that interferon may harm thyroid function. An estimated 40-50 percent of those who receive interferon treatment develop hypothyroidism while 10-30 percent develop hyperthyroidism. This consequence of treatment has been named Interferon Induced Thyroiditis (IIT). Fortunately, studies show that IIT is usually resolved and thyroid function restored after cessation of interferon therapy.
Interferon is frequently used to treat a variety of cancers and common viral infections such as hepatitis C, hepatitis B, and condylomata acuminate. Common interferon medications include Alferon N, Interon A, Pegasys, PegIntron, Sylatron, and Roferon-A.
Accumulation of lithium in the thyroid can inhibit hormone synthesis and release, and may contribute to the destruction of thyroid cells. Studies also show that lithium may increase the risk of goiter, hypothyroidism, and autoimmune thyroid disease. The thyroid gland naturally accumulates lithium meaning that increased intake or exposure to lithium often results in dangerously high concentrations in the thyroid.
Lithium may be prescribed to treat conditions such as depression, bipolar disorders, schizophrenia, and certain blood disorders. Common lithium medications include generics such as Lithium Citrate, Lithium Carbonate and brand names such as Lithobid, Eskaltih, and Lithate.
Avoiding Problematic Medications to Protect Your Thyroid
Healthy thyroid function is essential for maintaining good health. Sadly, many are unwittingly harming their thyroid by taking certain medications. Effectively protecting thyroid function requires familiarity with these thyroid-disrupting medications and taking the appropriate steps to limit their usage.
If you are currently taking one or more of the above medications, speak to your doctor about the impact they have on your thyroid and the possibility of pursuing a more thyroid-conscious treatment plan.
Resources1. Harari F, Bottai M, Casimiro E, et al. “Exposure to lithium and cesium through drinking water and thyroid function during pregnancy: a prospective cohort study.” Thyroid. 2015;25(11):1199-208.
2. Kraszewska A, Abramowicz M, Chłopocka-Woźniak M, et al. “The effect of lithium on thyroid function in patients with bipolar disorder. “ Psychiatr Pol. 2014;48(3):417-28.
3. Kibirige D, Luzinda K, Ssekitoleko R. “Spectrum of lithium induced thyroid abnormalities: a current perspective.” Thyroid Research. 2013;6:3.
4. Dong B. “How medications affect thyroid function.” West j Med. 2000;172(2): 102–106.
5. Tsang W, Houlden R. “Amiodarone-induced thyrotoxicosis: A review.” Can J Cardiol. 2009; 25(7): 421–424.
6. Narayana S, Woods D, Boos C. “Management of amiodarone-related thyroid problems.” Ther Adv Endocrinol Metab. 2011; 2(3):115–126.
7. Peckham S, Lowery D, Spencer S. “Are fluoride levels in drinking water associated with hypothyroidism prevalence in England? A large observational study of GP practice data and fluoride levels in drinking water.” J Epidemiol Community Health 2015;69:619-624.
8. Singh N, Verma KG, Verma P, Sidhu GK, Sachdeva S. ” A comparative study of fluoride ingestion levels, serum thyroid hormone & TSH level derangements, dental fluorosis status among school children from endemic and non-endemic fluorosis areas.” SpringerPlus. 2014;3:7.
9. Irving S, Vadiveloo T, Leese G. “Drugs that interact with levothyroxine: an observational study Thyroid Epidemiology, Audit and Research Study (TEARS).” Clin Endocrinol (Oxford). 2015;82(1):136-141.
10. Liwanpo L, Hershman J. “Conditions and drugs interfering with thyroxine absorption.” Best Pract Res Clin Endocrinol Metab. 2009;23(6):781-792.
11. Tomer Y, Blackard JT, Akeno N. “Interferon Alpha Treatment and Thyroid Dysfunction” Endocrinology and metabolism clinics of North America. 2007;36(4):1051-1066.