What You Should Know About Adthyza Side Effects

Every medication comes with potential side effects, and Adthyza is no exception. Whether you were taking Adthyza before its discontinuation in November 2025 or you're now on a similar natural desiccated thyroid (NDT) medication like Armour Thyroid, understanding the side effect profile helps you know what's normal and what needs medical attention.

This guide covers the common and serious side effects associated with Adthyza and other desiccated thyroid products, which populations face higher risks, and practical tips for managing side effects.

What Is Adthyza?

Adthyza was a brand-name natural desiccated thyroid medication manufactured by Azurity Pharmaceuticals. It contained both Levothyroxine (T4) and Liothyronine (T3) derived from porcine (pig) thyroid glands. It was prescribed for hypothyroidism, goiter prevention, and adjunctive therapy in thyroid cancer.

Adthyza was discontinued in late November 2025, but the side effect information applies equally to other NDT products like Armour Thyroid and NP Thyroid, which contain the same active hormones. For a full overview of the drug, see our guide: What Is Adthyza? Uses, Dosage, and What You Need to Know.

Common Side Effects

Most side effects from desiccated thyroid medications occur when the dose is being adjusted or when hormone levels are slightly too high. Common side effects include:

• Temporary hair loss — especially common in children during the first few months of treatment. This usually resolves on its own as the body adjusts.
• Headache — typically mild and most common when starting treatment or after dose changes.
• Tremor — slight shaking of the hands, often a sign that your dose may be slightly too high.
• Fatigue or sluggishness — can occur when the dose isn't quite right (too low or during adjustment periods).
• Weight changes — some patients experience weight loss as thyroid levels normalize; others may notice fluctuations during dose changes.
• Nausea — taking your medication on an empty stomach can sometimes cause mild nausea.
• Dry skin — may persist until thyroid levels stabilize at the optimal range.
• Sweating (hyperhidrosis) — increased sweating can indicate your dose is slightly too high.
• Joint pain (arthralgia) — some patients report mild joint discomfort.
• Muscle pain (myalgia) — similar to joint pain, usually mild and temporary.

Many of these side effects improve once your dose is optimized. If any persist for more than a few weeks, let your doctor know — it often means your dosage needs fine-tuning, not that you need to stop the medication.

Serious Side Effects — When to Call Your Doctor

Some side effects require immediate medical attention. Contact your doctor right away or seek emergency care if you experience:

• Chest pain or angina — could indicate that thyroid hormones are putting too much strain on your heart.
• Rapid or irregular heartbeat (palpitations) — a sign of possible thyroid hormone excess. This is especially concerning in older adults or anyone with a heart condition.
• Allergic reactions — hives, facial swelling, or difficulty breathing. While rare, allergic reactions to inactive ingredients in NDT products can occur.
• Severe anxiety or nervousness — excessive thyroid hormone can overstimulate your nervous system.
• Excessive sweating or heat sensitivity — beyond normal sweating, this may signal thyrotoxicosis (too much thyroid hormone).
• Seizures — rare, but possible with overdose.
• Severe insomnia — persistent inability to sleep that doesn't improve.
• Depression — new or worsening mood changes should always be reported.
• Blood pressure changes — both high and low blood pressure can occur.
• Signs of thyrotoxicosis — fever, confusion, rapid heart rate, or in extreme cases, coma. This is a medical emergency.

Important Safety Warning

Adthyza and all thyroid hormone medications carry a boxed warning (the FDA's most serious warning): thyroid hormones should not be used for weight loss. In patients with normal thyroid function, doses large enough to cause weight loss can produce serious or even life-threatening side effects — especially when combined with appetite suppressants or stimulants.

Side Effects in Specific Populations

Elderly and Cardiac Patients

Older adults and people with heart conditions are at higher risk for cardiovascular side effects like palpitations, chest pain, and arrhythmias. Doctors typically start these patients at a lower dose — as low as 16.25 mg (1/4 grain) per day — and increase very slowly, monitoring closely with blood work and cardiac assessments.

Pregnant and Breastfeeding Women

Thyroid hormone replacement is generally considered safe during pregnancy and is often necessary — untreated hypothyroidism during pregnancy carries serious risks for both mother and baby. However, your dose may need adjustment during pregnancy because thyroid hormone requirements often increase. Your doctor should check your TSH levels every 4-6 weeks during pregnancy.

Small amounts of thyroid hormones pass into breast milk, but this is generally considered safe for breastfeeding mothers.

Children

Temporary hair loss is more common in children starting thyroid medication. Dosing is based on the child's age and weight, and treatment for congenital hypothyroidism should begin as soon as it's diagnosed to prevent developmental delays.

Patients with Adrenal Insufficiency

People with untreated adrenal insufficiency (low cortisol) should not take Adthyza or any thyroid hormone until their adrenal condition is treated. Starting thyroid hormones without correcting adrenal insufficiency can trigger an adrenal crisis, which is a medical emergency.

How to Manage Common Side Effects

Here are practical tips for dealing with the most common side effects:

For Nausea

Take your medication with a small sip of water on an empty stomach, 30-60 minutes before breakfast. If nausea persists, ask your doctor about taking it at bedtime instead (at least 3 hours after your last meal).

For Headaches and Tremors

These often mean your dose is slightly too high. Don't adjust your dose on your own — talk to your doctor. They may reduce your dose by a small amount (typically 16.25 mg) until the symptoms resolve.

For Hair Loss

This is almost always temporary. Ensure you're getting adequate protein, iron, and biotin in your diet. If hair loss continues beyond 3-4 months, ask your doctor to recheck your thyroid levels.

For Sweating and Heat Sensitivity

Excess sweating usually indicates your thyroid hormone levels are running high. Report this to your doctor, as a dose reduction may be needed.

General Tips

• Take your medication at the same time every day for consistent hormone levels
• Avoid calcium, iron supplements, and antacids within 4 hours of your thyroid medication — they interfere with absorption
• Don't skip doses, and don't double up if you miss one
• Get your blood work done on schedule — regular TSH, Free T4, and Free T3 monitoring is essential

For information on substances that can interact with your thyroid medication, read our guide on Adthyza Drug Interactions: What to Avoid.

Final Thoughts

Most side effects from Adthyza and similar NDT medications are manageable and often temporary — especially during the initial dosing period. The key is working closely with your doctor to find the right dose and reporting any new or worsening symptoms promptly.

If Adthyza's discontinuation has you transitioning to a new thyroid medication, be aware that side effects may resurface temporarily as your body adjusts to the new formulation. This is normal. Give it time, stay in close contact with your prescriber, and monitor your labs regularly.

Looking for your thyroid medication? Medfinder can help you find NDT alternatives in stock near you. And for a full list of options, visit our Alternatives to Adthyza guide.