Thyroid Armour Manufactured by Forest (Desiccated Thyroid)

Armour Thyroid is a prescription medication used to treat an underactive thyroid, also called hypothyroidism. It is made from dried pig thyroid glands and helps replace hormones your thyroid does not make enough of. Unlike levothyroxine, which contains only one thyroid hormone called T4, Armour Thyroid contains both T4 and T3. These hormones help control energy, body temperature, metabolism, growth, and other bodily functions. Armour Thyroid may also be used in some thyroid cancer treatments and to lower TSH levels in certain non-cancerous goiters.

Directions

Armour Thyroid is taken by mouth once a day, usually in the morning before eating. Your dose depends on your age, weight, health problems, other medicines, and thyroid levels. Take it at the same time each day, and do not stop or change your dose without guidance from a healthcare provider. For adults with low thyroid, treatment often starts with a low dose, such as 30 mg daily, and may be increased every 2 to 3 weeks. Many adults end up taking 60 to 120 mg daily, but older adults or people with possible heart disease may start at 15 mg daily. For babies and children, the dose is based on age and weight and is adjusted regularly based on thyroid levels.

Ingredients

The active ingredient in Armour Thyroid is desiccated natural thyroid derived from porcine thyroid glands. The inactive ingredients may include calcium stearate, dextrose, microcrystalline cellulose, sodium starch glycolate, and Opadry white.

Cautions

Before using this medication, you may want to consult a healthcare provider about the following:

• Any existing health conditions
• Any allergies
• A list of all medications currently being taken

Armour Thyroid and other thyroid hormones should never be used for weight loss or to treat obesity. In people with normal thyroid function, thyroid hormone has no proven benefits for reducing weight, and high doses can cause toxic effects.

Use caution if you have heart disease, including coronary artery disease, angina, irregular heart rhythms, or a history of heart attack. Too much thyroid hormone can speed up the heart, increase blood pressure, and worsen angina.

Tell your provider if you have diabetes (type 1 or type 2). Starting or stopping Armour Thyroid can change how much insulin or oral diabetes medication you need.

Armour Thyroid can change how blood thinners such as warfarin work, often making them more potent. Closer monitoring of INR (prothrombin time) and possible dose adjustments of the anticoagulant are usually needed.

Cholestyramine, colestipol, calcium supplements, iron supplements, antacids containing aluminum or magnesium, sucralfate, and proton pump inhibitors can reduce how much Armour Thyroid is absorbed. Separate these by at least 4 hours from your dose.

Estrogen-containing products such as oral contraceptives or hormone replacement therapy can change thyroid-binding proteins. People without functioning thyroids may need a higher Armour Thyroid dose when estrogen is started, and the dose may need to be reduced when estrogen is stopped.

High doses can cause symptoms of hyperthyroidism, including rapid heartbeat, palpitations, sweating, heat intolerance, tremor, weight loss, anxiety, irritability, or trouble sleeping.

Long-term over-replacement with thyroid hormone can reduce bone mineral density and increase the risk of osteoporosis, especially in postmenopausal women.

Treatment is usually lifelong. Replacement therapy generally should not be stopped without medical advice, even during pregnancy. Thyroid hormone needs often increase during pregnancy and should be closely watched.

Let your provider or dentist know you take Armour Thyroid before any planned surgery or procedure.

Contraindications

Avoid taking or using this medication if any of the following apply:

• Diagnosed but untreated adrenal cortical insufficiency.
• Untreated thyrotoxicosis (an overactive thyroid that has not yet been controlled).
• A known hypersensitivity to any active or inactive component of Armour Thyroid.

Side Effects

Most side effects of Armour Thyroid are signs that the dose is too high. These can include:

• Fast or irregular heartbeat or palpitations
• Chest pain or pressure
• Excessive sweating or heat intolerance
• Nervousness, irritability, or trouble sleeping
• Tremor or shakiness
• Headache
• Increased appetite with unintended weight loss
• Diarrhea or vomiting
• Changes in menstrual periods
• Muscle weakness or leg cramps
• Skin rash or hair thinning (in children, partial hair loss is usually temporary)

Get medical help for any signs of a serious allergic reaction such as swelling of the face, lips, tongue, or throat, trouble breathing, or a severe rash.

Other serious problems can include chest pain, very fast or irregular heartbeat (such as atrial fibrillation), heart attack symptoms, seizures, and confusion.

In infants, doses that are too high can affect the skull and may lead to early closure of the soft spot (craniosynostosis).

Long-term high doses may also lead to weakened bones, so any concerns about osteoporosis risk should be discussed with a healthcare provider.

References

• Armour Thyroid Highlights of Prescribing Information. St. Louis, MO: Forest Pharmaceuticals, Inc.; 2026.
• Armour Thyroid Drug Label Information. North Chicago, IL: AbbVie, Inc.; 2024.