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How Birth Control Affects Thyroid Function

How Birth Control Affects Thyroid Function

The thyroid is a small gland located in the neck that influences nearly all bodily functions. Many factors are involved in proper thyroid activity and malfunction in one area can result in significant dysfunction.

Hypothyroidism is a common thyroid disorder, most often seen in women, that limits thyroid function and causes an array of symptoms. Although there are many possible causes of hypothyroidism, there is one prominent yet often-overlooked contributor…

The Prolific Use of Birth Control

At some point during their life, most women will have a doctor recommend that they take birth control. This is supported by CDC data suggesting that oral contraception, commonly known as “the pill,” is used by over 10 million women in the U.S. alone. Even though estrogenic birth control medications are primarily used to prevent pregnancy, doctors often prescribe them to aid in other areas. It is common practice for doctors to recommend birth control medications to treat symptoms of PMS, acne, heavy menstruation, irregular periods, and other hormone-related issues. Sadly, these recommendations are made, and birth control used without proper understanding of the impact it has on other systems such as the thyroid.

The Impact of Birth Control on the Thyroid

The primary influence of birth control over thyroid function involves an increase in estrogen. Birth control medications typically contain a high volume of estrogen that can skew hormone balance resulting in dysfunction. In addition to disrupting hormone balance, birth control negatively influences specific aspects of thyroid function including nutrient availability and hormone transport while also increasing the risk of autoimmune dysfunction.

Birth Control Depletes Important Thyroid Nutrients

To function properly, the thyroid requires a regular supply of various vitamins, minerals, and nutrients – learn about the most common nutrient deficiencies in thyroid patients here. For example, the thyroid uses selenium and zinc to produce thyroid hormones and convert the inactive form of thyroid hormone T4 (thyroxine) into the active form T3 (triiodothyronine). In addition to these processes, zinc in particular is necessary for communication between thyroid hormones and cell receptors. Therefore, a deficiency of influential substances such as these can result in a major thyroid malfunction.

B Vitamins, particularly B6, B9 (Folic Acid), and B12, are also an important component of thyroid hormone activity. A deficiency of B Vitamins can cause the body to become incapable of producing thyroid hormone and may also prompt the development of symptoms including anemia, depression, and fatigue.

Birth control medications can sap the body’s supply of essential nutrients including selenium, zinc, and B Vitamins. This means that improper use of birth control can interfere with nearly every stage of thyroid hormone activity including synthesis, signaling, transport, and usage.

Birth Control Impedes Thyroid Hormone Activity

Thyroid Binding Globulin (TBG) is an important component of thyroid function. TBG joins thyroid hormones T4 and T3 allowing for easier transport through the bloodstream and improving cellular utilization of thyroid hormone. Therefore, maintaining an appropriate level of TBG is important.

Birth control medications containing high doses of estrogen promote TBG production to a potentially harmful degree. Research shows that after only six weeks of estrogen-based therapies, levels of TBG increase significantly in hypothyroid women. Elevated TBG levels triggers greater thyroid hormone binding, which reduces hormone availability. A lack of circulating thyroid hormone in the form of Free T4 and Free T3 can cause symptoms of hypothyroidism even though tests may suggest normal levels in the bloodstream.

Reduce thyroid hormone availability due to increased TBG also prompts an increase of TSH. An elevated TSH level may result in unnecessary production of thyroid hormone. Such action can impede thyroid hormone activity and contribute further to symptoms of hypothyroidism.

Birth Control Promotes Inflammation and Autoimmune Dysfunction

Most birth control medications cause a notable degree of inflammation. Oral contraceptives in particular can trigger a shift from Th1 immunity to Th2, which is associated with a greater degree of inflammation with an extended duration. Sustained inflammation, such as that triggered by the Th2 immune response, significantly increases the risk of developing chronic disease such as the autoimmune thyroid disorders Hashimoto’s thyroiditis and Graves’ disease.

Inflammation caused by birth control also has a direct impact on hormone activity. Highly estrogenic birth control medications can instigate inflammation that promotes conversion of T4 into the inhibitory mirrored version of active form of thyroid hormone Reverse T3 (RT3). If levels of RT3 are increased to an inappropriate level, thyroid hormone activity can be severely inhibited and cause a patient to suffer from symptoms of hypothyroidism. Increased inflammatory activity also limits cellular receptivity to hormones, meaning that thyroid hormones are less capable of regulating overall bodily function.

Stay Informed About the Effects of Birth Control

Even though birth control provides some benefits there are potentially harmful effects that should be considered. The significant hormonal impact of birth control medications can greatly disrupt thyroid function. Multiple effects of birth control such as nutrient depletion, increased TBG production, and greater inflammatory activity all contribute to thyroid dysfunction. Women taking birth control who are suffering from hypothyroidism or other thyroid related dysfunction should speak with a doctor about other contraceptive options or methods to improve hormone balance. Birth control is a powerful tool when used in the appropriate circumstances. However, before using them, patients should always consider what effect birth control medications will have on important systems such as the thyroid.


1. Jolene Brighten, ND. “What doctors don’t say about the birth control and thyroid connection.” Hypothyroid Mom.

2. Jo Jones, Ph.D.; William Mosher, Ph.D.; and Kimberly Daniels, Ph.D., Division of Vital Statistics. “Current Contraceptive Use in the United States, 2006–2010, and Changes in Patterns of Use Since 1995.” National Health Statistics Report. Number 60, October 18, 2012.

3. Agren, U et al. “Effects of a monophasic combined oral contraceptive containing nomegestrol acetate and 17β-oestradiol in comparison to one containing levonorgestrel and ethinylestradiol on markers of endocrine function.” Eur J Contracept Reprod Health Care. 2011 Dec;16(6):458-67.

4. Raps, M et al. “Use of hormonal contraceptives lead to elevated TBG levels, slightly elevated TSH levels.” Thromb Res. 2014 Apr;133(4):640-4.

5. Santin, A et al. “Role of Estrogen in Thyroid Function and Growth Regulation.” J Thyroid Res. 2011; 2011: 875125.

6. Izabella Wentz, Pharm D. “14 Ways Birth Control Pills Rob Us of Our Health.” Thyroid Pharmacist.

7. Jolene Brighten, ND. “Is The Pill At The Root Of Your Thyroid Problem?” MindBodyGreen.