Adthyza is a prescription thyroid medication made from dried pig thyroid glands. Manufactured by Azurity Pharmaceuticals and introduced in February 2023, it belongs to a class of drugs called desiccated thyroid extracts (DTEs) used to treat hypothyroidism, a condition where the thyroid gland doesn’t produce enough hormones on its own.
What Adthyza Contains
Unlike synthetic thyroid medications that contain only one hormone, Adthyza delivers both of the thyroid hormones your body naturally produces: T4 (levothyroxine) and T3 (liothyronine). Each 65 mg of thyroid powder provides 38 mcg of T4 and 9 mcg of T3. This matters because T3 is roughly four times as potent as T4 on a microgram-for-microgram basis, so even a small amount has significant effects.
The active ingredient is porcine thyroid gland tissue that has been dried and defatted into a powder. This powder contains a protein called thyroglobulin, which your body breaks down to release T4 and T3. Because of its animal origin, the tablets may have a noticeable odor, and people with pork allergies should not take them.
How It Compares to Other Thyroid Medications
Adthyza is one of several desiccated thyroid products on the market, alongside well-known brands like Armour Thyroid and NP Thyroid. All of these share the same basic composition: dried pig thyroid gland providing both T4 and T3. The key difference from synthetic options like levothyroxine (Synthroid, Levoxyl) is that synthetic versions contain only T4, relying on your body to convert some of it into the more active T3.
One important characteristic of all desiccated thyroid products, Adthyza included, is that they contain variable amounts of T3 and other thyroid compounds. This variability can cause more fluctuations in hormone levels compared to synthetic medications, which is why some patients notice more ups and downs in how they feel. Some people prefer this combination approach and report feeling better on desiccated thyroid than on synthetic T4 alone, though individual responses vary widely.
FDA Approval Status
Adthyza occupies an unusual regulatory space. No desiccated thyroid product currently on the market has been formally approved by the FDA. These medications have been sold for decades, predating the modern FDA approval process, and continue to be marketed without going through the standard review. A 2024 citizen petition filed with the FDA raised concerns that newer entrants to the market, including Adthyza, do not appear to hold the type of investigational applications that would lead to formal licensure, meaning they are not subject to the same manufacturing and quality oversight as FDA-approved drugs.
More than a million people in the United States use desiccated thyroid products to manage hypothyroidism and other thyroid conditions, so these medications have a long track record of clinical use despite their regulatory status.
Available Strengths
Adthyza comes in five tablet strengths, measured in both milligrams and the older “grain” system that desiccated thyroid products have traditionally used:
- ¼ grain (15 mg): 9.5 mcg T4, 2.25 mcg T3
- ½ grain (30 mg): 19 mcg T4, 4.5 mcg T3
- 1 grain (60 mg): 38 mcg T4, 9 mcg T3
- 1½ grain (90 mg): 57 mcg T4, 13.5 mcg T3
- 2 grain (120 mg): 76 mcg T4, 18 mcg T3
The range of strengths allows for dose adjustments based on blood work. Most people start at a lower dose and increase gradually until thyroid levels stabilize.
Side Effects and Safety Concerns
The most common side effect is temporary hair loss during the first few months of treatment, which typically resolves as the body adjusts. Most other side effects stem from getting too much thyroid hormone, essentially pushing the body into a hyperthyroid state. Signs of this include increased sweating, sensitivity to heat, nervousness, mood swings, diarrhea, tremor, headache, and fatigue.
More serious symptoms that require immediate attention include chest pain, a fast or irregular heartbeat, swelling in the hands, ankles, or feet, and seizures. These indicate dangerously elevated thyroid hormone levels.
Adthyza carries a warning that it should never be used for weight loss. At normal doses it won’t cause weight loss, and at high doses it can produce severe, potentially fatal effects, particularly when combined with diet pills. People with heart disease, high blood pressure, diabetes, or adrenal gland problems need careful monitoring when taking any thyroid hormone replacement.