Armour Thyroid vs Levothyroxine: How Do They Compare?

Key Takeaways

• Levothyroxine is a synthetic form of the thyroid hormone, made naturally by the human thyroid gland. Armour Thyroid is the brand name for a natural form of thyroid hormone obtained from animal thyroid glands. 

• The U.S. Food and Drug Administration (FDA) has not approved Armour Thyroid. Doctors avoid prescribing it because it is made from drying and crushing porcine (pig) thyroid glands and may contain variable strengths of thyroid hormones.

• Levothyroxine is the recommended standard treatment for hypothyroidism. However, if levothyroxine has not provided symptom relief, talk to your health care provider about Armour Thyroid.

Armour Thyroid and levothyroxine are prescription medications that are used for treating hypothyroidism (underactive thyroid gland) and certain other thyroid disorders, such as thyroid cancer. However, there are some key differences between them. Please continue reading to learn more. 

What is levothyroxine?

Levothyroxine or L-thyroxine is a prescription medication. It is a synthetic form of the thyroid hormone thyroxine (T4), which is made naturally by the human thyroid gland. Levothyroxine is a generic drug. It is also sold under brand names such as Synthroid, Levo-T, Levoxyl, Unithroid, and Tirosint. 

What is Armour Thyroid?

Armour Thyroid is the brand name for a natural form of thyroid hormone obtained from animal thyroid glands. Other brand names include NP Thyroid, Nature-Throid, and Natural Thyroid. These products contain desiccated thyroid extract and provide both T4 and T3 (thyroxine and triiodothyronine) combination therapy.

What are the differences between levothyroxine vs Armour Thyroid?

What are the similarities between Armour Thyroid and levothyroxine?

• Both Armour Thyroid and levothyroxine are prescription medications. 

• They are used for the treatment of hypothyroidism to provide thyroid hormone replacement. 

• Both medications are available in pill form in a variety of strengths.

• Doses of Armour Thyroid and levothyroxine are adjusted based on symptom relief and the results of blood tests such as thyroid stimulating hormone (TSH), which indicate if thyroid hormone levels are in the desired range.

• Possible side effects of levothyroxine and Armour Thyroid include weight loss or weight gain, changes in appetite, headache, vomiting, diarrhea, increased sweating, fever, hair loss, joint pain, and menstrual cycle changes. These potential side effects can be similar to the symptoms of hyperthyroidism (overactive thyroid gland) and may indicate that the dose of thyroid hormone replacement is too high. Serious side effects include allergic reactions.

• Both Armour Thyroid and levothyroxine can interact with other medications and certain foods. This can affect how well the medications work and can also increase the risk of serious adverse effects. 

• You need to take both types of thyroid replacement therapy once a day in the morning on an empty stomach, 30-60 minutes before the first meal of the day.

• Treatment with Armour Thyroid and levothyroxine is lifelong in most patients.

Frequently Asked Questions

What is an underactive thyroid gland?

The thyroid gland produces thyroid hormones T4 and T3, which play a role in many important processes and keep the body functioning properly. In people with an underactive thyroid gland (hypothyroidism), the thyroid gland does not make enough thyroid hormone. This affects many bodily functions. Common symptoms of hypothyroidism include fatigue, weight gain or problems losing weight, cold intolerance, joint and muscle pain, dry skin, thinning hair, memory problems, depression, menstrual irregularities, slow heart rate, and increased blood pressure. 

Check out 8 signs you may have a thyroid condition.

What is thyroid hormone replacement therapy?

Doctors prescribe thyroid hormone replacement (such as levothyroxine or Armour Thyroid) to treat hypothyroidism. These medications replace or supplement thyroid hormones in hypothyroid patients whose thyroid glands don’t make enough thyroid hormone. Thyroid hormone replacement therapy consists of taking medications by mouth to normalize thyroid function by supplementing or replacing thyroid hormones. 

Why won’t doctors prescribe Armour Thyroid?

Doctors avoid prescribing Armour Thyroid because it is an animal-based product made from drying and crushing porcine (pig) thyroid glands. As a result, it may contain variable potencies (strengths) of thyroid hormones. The synthetic versions of thyroid hormone replacement (such as levothyroxine) are made in a laboratory. It is, therefore, easier to ensure hypothyroid patients are taking the correct dose of thyroid hormone with levothyroxine compared to Armour Thyroid.

Another reason for avoiding Armour Thyroid is the potential for allergic reactions. Desiccated natural thyroid is often processed at facilities that also handle other animal tissues, such as bovine (cow) tissues. Potential contamination among the various products and exposure to bovine or porcine viruses is, therefore, a risk with thyroid hormone replacement products such as Armour Thyroid.

Why is Armour Thyroid not FDA-approved?

Armour Thyroid is not FDA-approved because it and other products that contain desiccated thyroid extract (DTE) from animal sources have not undergone rigorous testing for quality, safety, and effectiveness.

Why do doctors prefer levothyroxine versus Armour Thyroid?

Doctors prefer levothyroxine over Armour Thyroid because of the consistent manufacturing process for laboratory-made levothyroxine. This ensures that each tablet of levothyroxine contains the correct amount of thyroid hormones. 

In contrast, due to a complex and unregulated manufacturing process, desiccated thyroid extract (DTE) often contains inconsistent and inaccurate dosages, leading to quality, safety, and efficacy issues. For this reason, drug recalls for DTE products are common. 

It is noteworthy that studies suggest even small changes in thyroid hormone levels can have significant effects on bodily functions. Too little medicine can be ineffective, and too much medication can cause severe side effects.

What are the signs your thyroid medication is not working?

What are the benefits of taking Armour Thyroid?

The potential benefits of taking Armour Thyroid are that it contains both T4 and T3. Levothyroxine contains only T4, which the body converts into T3. Some people continue to experience symptoms of hypothyroidism while taking levothyroxine despite having thyroid hormone levels in normal ranges. Such people sometimes get symptom relief after switching to a natural product such as Armour Thyroid, which contains both T4 and T3.

What is the best thyroid medicine to take?

Hypothyroidism treatment requires individualized therapy, and finding the best thyroid medicine and dosage can take time. It is best to take FDA-approved treatment options such as levothyroxine as they provide consistent and precise dosing. Levothyroxine is also the recommended standard treatment of hypothyroidism according to the American Thyroid Association guidelines. However, if levothyroxine has not provided symptom relief and you want to try Armour Thyroid to treat hypothyroidism, you should talk to your health care provider.