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Are Medications Hindering Your Thyroid Health?

Are Medications Hindering Your Thyroid Health?

The thyroid gland is highly integrated with the rest of the body and has significant influence over numerous functions. Therefore, even mild disruption of the thyroid can result in various symptoms such as an erratic metabolism, weight fluctuations, cognitive difficulties, and more. The trigger of such disruption may have an unlikely source, your medications.

A major component of treating the thyroid is testing thyroid hormone levels to determine the appropriate dosage of thyroid medications (get a free sample lab slip here). For those with a thyroid condition it can be a long and difficult process of testing, medicating, and retesting until the correct dose is established. Unfortunately, this process can be extended and made more challenging if patients and doctors are unaware of possible medicinal interactions. The following categories of medications can have a negative impact on thyroid treatment and function and should typically be avoided by those with a thyroid disorder.


Anticonvulsants used to treat epilepsy can quickly over-utilize thyroid hormones resulting in a deficiency. Thyroid patients using anticonvulsants may experience greater thyroid degradation and dysfunction. Anticonvulsants may also inhibit the release of T4 into the bloodstream and block T4 to protein binding thereby limiting thyroid hormone availability. In younger patients, anticonvulsants may result in increased TSH levels, which can mask an existing thyroid issue.

Some anticonvulsants to be wary of when taking thyroid medications include:

  • Phenytoin
  • Phenobarbital
  • Carbamazepine
  • Diphenylhydantoin
  • Valproic acid

Medications with Iodine

Iodine is an essential part of thyroid hormone production and activity. Even though it may seem like medications containing iodine could only benefit thyroid function, this is not the case. Excessive levels of iodine can contribute to increased thyroid hormone production and cause symptoms similar to hyperthyroidism. Medications containing iodine may also cause anxiety and heart palpitations, which are common indicators of increased thyroid activity. Excess iodine often results in an immediate spike in thyroid activity resulting in later hormonal deficiency.

Water Tablets

Edema, or excess fluid in the body, is a common problem among those experiencing heart failure, liver disease, and kidney disease. Furosemide water tablets are used to eliminate excess fluid in the body by promoting the production of urine. They may also be used to treat high blood pressure, which reduces the risk of heart attacks, stroke, and kidney issues. Regarding thyroid health, the increased concentration of thyroid hormones that comes with limiting water content in the blood stream may result in a perceived increase in thyroid hormone even though levels haven’t actually changed. This can wrongfully indicate elevated thyroid levels resulting in improper treatment.


Estrogen is the primary female sex hormone and is involved in a variety of processes including mood regulation, weight control, thyroid function and much more. When estrogen is produced in greater volume, thyroid levels also appear to increase as well. However, this growth does not reflect any additional thyroid activity. A false image of thyroid activity can cause test results to appear balanced even though they true thyroid levels are deficient.

Learn more about the connection between estrogen and thyroid function here.


Antibiotics can be problematic in many ways if they are not used correctly. Over use of antibiotics can significantly disrupt gut function thereby promoting immune and thyroid dysfunction. Some antibiotics such as ciprofloxacin and quinolone products disrupt thyroid medication and function by either hastening metabolization or limiting absorption. Other antibiotics such as rifaximin can significantly increase thyroid medication absorption, which may result in symptoms similar to hyperthyroidism or excessive thyroid activity. If antibiotics are unavoidable, it is best to use them 4 to 6 hours before or after taking thyroid medications.

Staying on the Lookout

In addition to the more specific categories above, there are many common medications that influence the thyroid in a variety of ways. The following drugs and classifications can influence test results making it more difficult to appropriately medicate patients. These substances can also disrupt thyroid function and inhibit the efficacy of thyroid medications.

  • Amiodarone Hydrochloride – Medication used in treating irregular heart beat or arrhythmia
  • Androgens – Male sex hormones that may be used to treat a deficiency
  • Antacids – Many antacids contain aluminum hydroxide, which can hinder thyroid hormone absorption
  • Beta blockers such as Propranolol and Inderal – For treating high blood pressure
  • Diazepam – Treats anxiety, muscle spasms, and seizures
  • Insulin or other blood sugar regulators – Common treatment for diabetics that may inhibit thyroid hormone replacement therapies
  • Lithium – Psychiatric recovery and relapse prevention
  • Oxymetazoline Hydrochloride – Used to treat nasal congestion but may be harmful to those with heart, kidney, and thyroid disorders, as well as those with diabetes or hypertension
  • Phenothiazines – Powerful tranquilizers
  • Phenylbutazone – Used for treating Bechterew’s disease, an inflammatory spinal condition
  • Prochlorperazine – An antipsychotic that treats schizophrenia, anxiety, nausea, and vomiting
  • Salicylates – Commonly found in pain killers such as aspirin
  • Statins – This category of drug is used to lower cholesterol, but statins may bind to thyroid hormones making thyroid medications less effective
  • Steroids – Typically used for physical recovery
  • Sulfonamides – Used to treat glaucoma and aid in fluid retention
  • Tamoxifen – Estrogen modulating substance that helps prevent various cancers
  • Tolbutamide and Chlorpropamide – Both are common diabetes medications
  • Warfarin, Coumadin, and Heparin – Blood thinners that may increase in strength in the presence of thyroid medications

In addition to altering test results, these medications can significantly impede thyroid function and thyroid medications. In some cases, over-use or exposure to these medications, particularly lithium, may promote the development of autoimmune disorders such as Hashimoto’s thyroiditis.

Protect the Thyroid by Avoiding Harmful Interactions

There are many drugs and medications that can negatively impact the thyroid and thyroid replacement therapies. Those with a thyroid condition should be particularly wary of antibiotics, anticonvulsants, and medications containing iodine or estrogens. Many common medications such as those used to treat diabetes, high cholesterol, and high blood pressure can also disrupt thyroid treatment and activity. Because of the many potential interactions, it is important to disclose any and all of your current medications to your doctor before beginning new treatments. Protect yourself and your thyroid by being aware of potentially harmful interactions and avoiding disruptive medications.


1. What’s Interfering With Your Thyroid Medication? Holtorf Medical Group.

2. Medications That Can Strain Your Thyroid. Thyroid Nation.

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