Armour Thyroid vs. Levothyroxine for Hypothyroidism: 7 Differences to Know

If you have hypothyroidism (low thyroid hormone levels), your primary care provider will typically recommend thyroid hormone replacement therapy. For most people, levothyroxine (Synthroid, Levoxyl, Tirosint, Unithroid) is the first treatment that’s recommended. It’s a synthetic (lab-made) version of the T4 thyroid hormone.

Even though levothyroxine is the first-choice treatment for hypothyroidism, you may have heard of levothyroxine alternatives like Armour Thyroid. Armour Thyroid (desiccated thyroid) is an older type of thyroid replacement. It’s sometimes referred to as a natural thyroid hormone replacement. This medication differs from levothyroxine in several key ways, which may determine whether or not it's right for you.

1. Armour Thyroid and levothyroxine are made differently

Synthetic thyroid medications first became available in the late 1940s. Before that, desiccated thyroid extracts, like Armour Thyroid, were the only treatment for hypothyroidism.

Today, thyroid extracts are made from the dried and ground thyroid glands of pigs. These products are sometimes called more “natural” because they come from animal products. In addition to Armour Thyroid, NP Thyroid is another natural thyroid medication available on the market.

In contrast, levothyroxine is a synthetic thyroid hormone made in a laboratory. It’s available as generic levothyroxine and as brand-name medications like Synthroid, Levoxyl, and Tirosint.

2. Each product contains different thyroid hormones

Your thyroid gland makes two main hormones: T4 (thyroxine) and T3 (triiodothyronine). T4 is an inactive form of thyroid hormone. Your body converts a portion of T4 into T3, which is the active form.

Armour Thyroid contains both T4 and T3 thyroid hormones, along with fillers and binders to hold everything together.

Levothyroxine contains a synthetic version of T4 thyroid hormone. Your body must convert T4 into T3. The medication also contains fillers and binders. Most tablets (but not the capsules) have artificial colors added.

For many people, taking T4 alone with levothyroxine is enough to raise low thyroid hormone levels. But your healthcare team may recommend adding synthetic T3 (liothyronine), which is taken as a separate medication.

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• Do natural treatments for hypothyroidism work? Here’s the evidence behind natural thyroid therapies.

3. The dosages for Armour thyroid and levothyroxine are different

When you first start thyroid replacement therapy, you usually begin with a low dose. If needed, your primary care provider will gradually increase the dose over time. Adjustments may be made based on lab results, any medical conditions you have, and the medication you take. Your age and weight can also determine your dose.

The dosing for Armour Thyroid and levothyroxine is different. For starters, Armour Thyroid is available in “grains.” One grain (about 60 mg) contains 38 mcg of T4 and 9 mcg of T3. The tablets are available in a range of doses from 15 mg (¼ grain) to 300 mg (5 grains).

Levothyroxine is available in micrograms. Tablets come in doses ranging from 25 mcg to 300 mcg of T4. It’s estimated that 1 grain of Armour Thyroid is about the same as 88 mcg of levothyroxine.

For children, doses for both medications are based on body weight. For adults, body weight is used to calculate the dose only for levothyroxine.

For both medications, it’s best to take doses in the morning on an empty stomach. This helps your body absorb more of the medication, making it more effective.

4. Levothyroxine products may have less variability

Thyroid replacement medications have a narrow therapeutic index. This means that even small changes in your dose can significantly affect how well the medication works. So it’s important that you receive the correct amount of thyroid hormones in each dose.

Levothyroxine products are made to consistently contain the correct amount of T4 in each dose. Brand-name and generic levothyroxine products have been shown to work equally well. And switching between generic products doesn’t appear to be an issue.

Desiccated thyroid extracts, like Armour Thyroid, are more complicated. In some cases, these products may not be as consistent from batch to batch. In other words, you could receive too little (or too much) T4 and T3 depending on the pill. In fact, recalls of these products regularly happen for this reason.

5. Armour Thyroid has unique risks to consider

Because of how it’s made, Armour Thyroid has a few unique risks that levothyroxine doesn’t. 

It’s not FDA approved 

Unlike levothyroxine, desiccated thyroid medications like Armour Thyroid aren’t FDA approved. These products were on the market before current FDA regulations existed. So, the FDA hasn’t reviewed their safety or effectiveness.

It contains a different ratio of thyroid hormones 

There’s a risk of getting too much T3 from medications like Armour Thyroid. The ratio of T4 to T3 in Armour Thyroid is different from what’s normally produced in humans. This is because it comes from pigs, which produce thyroid hormones in a different balance. 

There can be potential contamination risks

Armour Thyroid is made at a facility that also handles cow tissues. So there’s a potential risk of contamination with viruses, bacteria, or other germs. The manufacturer states there haven’t been any cases of disease transmission with Armour Thyroid.

For these reasons, in 2025 the FDA notified manufacturers and distributors of desiccated thyroid extracts (including Armour Thyroid) of their intent to take action against unapproved animal-derived thyroid medications. 

6. Levothyroxine is considered the gold standard for hypothyroidism treatment

Experts consider levothyroxine to be the first-choice treatment for hypothyroidism. This is because it works well and doesn’t have too many side effects. 

Levothyroxine is generally preferred over medications like Armour Thyroid. In addition to the risks discussed above, there isn’t a lot of long-term safety data on thyroid extracts.

What’s more, levothyroxine is specifically preferred as a treatment for pregnant women. That’s because the T3 in thyroid extracts can’t reach a developing baby’s brain. Because of this, Armour Thyroid shouldn’t be used to treat hypothyroidism during pregnancy.

7. Some people report feeling better with Armour Thyroid compared to levothyroxine

There aren’t many studies comparing Armour Thyroid and levothyroxine. But current data suggests that the T3 in Armour Thyroid doesn’t have additional benefits over taking T4 alone. Still, some people report feeling better when they take Armour Thyroid than when they take levothyroxine.

A recent study of 250 people found that those who switched from levothyroxine to Armour Thyroid felt better overall. But, compared to levothyroxine, more people stopped taking Armour Thyroid before 6 months of treatment. This was because of things like side effects and lack of symptom improvement.

Another smaller study of 70 people also showed a preference for desiccated thyroid over levothyroxine. In this study, the people who preferred desiccated thyroid lost weight and reported better memory, concentration, and sleep. Even so, more research is needed to confirm differences in effectiveness and side effects. 

Can you switch from Armour Thyroid to levothyroxine?

Armour Thyroid and levothyroxine aren’t interchangeable. But it’s possible to switch from one medication to the other. This should always be done under the supervision of a healthcare professional and requires a new prescription.

Your dose will change if you switch thyroid medications. But your healthcare team can help you find the closest match. They’ll also monitor your labs to make sure the new medication is working well for you.

How to save on prescription thyroid medications

There are many ways to save on your prescription thyroid medication. Consider taking advantage of GoodRx coupons, manufacturer savings cards, and more.

Save on Armour Thyroid

There are ways to save on Armour Thyroid, which is available only as a brand-name medication. GoodRx can help you navigate between GoodRx coupons, copay savings cards, and patient assistance programs to save money on your prescription:

• Save with GoodRx: Anyone with a valid prescription, regardless of insurance status, can use GoodRx to purchase a 30-day supply of Armour Thyroid at an exclusive cash price of $34.50.

• Save with a copay savings card: If you have commercial insurance, you may be eligible to pay as little as $35 for a 30- or 90-day prescription of Armour Thyroid using a savings card from the manufacturer.

• Save with patient assistance programs: If you’re uninsured or underinsured, you may be eligible for Armour Thyroid’s patient assistance program, which offers the medication free of charge.

Save on levothyroxine

Levothyroxine is available as a generic tablet and capsule. At certain pharmacies, generic levothyroxine’s price may be as low as $4.00 with a GoodRx coupon.

Levothyroxine tablets are also available as a number of brand-name products, including Synthroid, Levoxyl, and Unithroid: 

• Synthroid: If you’re eligible, you could pay as little as $25 a month with a manufacturer savings card. 

• Levoxyl: With a GoodRx coupon, you may be able to pay as little as $4.00 at certain pharmacies. 

• Unithroid: A manufacturer savings card may lower the cost to as little as $3 a month.

Tirosint and Ermeza are examples of brand-name levothyroxine oral solutions. The price for Ermeza may be as low as $283.29 at certain pharmacies with a GoodRx coupon.

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Written by:

Kristianne Hannemann, PharmD

Kristianne Hannemann, PharmD, is a licensed pharmacist in California. She has been a retail pharmacy manager and staff pharmacist for over 7 years and has contributed drug information content to different health companies.

Edited by:

Patricia Pinto-Garcia, MD, MPH

Patricia Pinto-Garcia, MD, MPH, is a medical editor at GoodRx. She is a licensed, board-certified pediatrician with more than a decade of experience in academic medicine.

Reviewed by:

Christine Giordano, MD

Christine Giordano, MD, is board-certified in general internal medicine. She received her medical degree from Rutgers New Jersey Medical School and completed residency at Thomas Jefferson University.

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