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Can you switch from Armour Thyroid to levothyroxine?

What to know if you’re considering switching from Armour Thyroid to levothyroxine
By | Feb. 13, 2025
Three prescription bottles: Can you switch from Armour Thyroid to levothyroxine?

Key takeaways

  • Armour Thyroid and levothyroxine are both thyroid hormone drugs that are used in the treatment of hypothyroidism, an underactive thyroid state.

  • Armour Thyroid consists of two thyroid hormone forms, triiodothyronine and thyroxine, and is derived from desiccated pig thyroids, whereas levothyroxine consists of synthetic thyroxine.

  • Levothyroxine is approved by the Food and Drug Administration and preferred over desiccated thyroid extracts in hypothyroidism care guidelines.

  • Product consistency could be better with levothyroxine, and its price may be lower than Armour Thyroid.

  • Converting from Armour Thyroid to levothyroxine can be done under the guidance of a healthcare provider who can recommend an appropriate dose and monitor its effectiveness with blood tests.

In this article:

Effective treatment of an underactive thyroid gland can increase energy levels and help with healthy weight maintenance. Treatment options involve taking supplemental thyroid hormone, which may include Armour Thyroid or generic and brand-name levothyroxine products. Based on medical expert recommendations and product consistency, people may want to switch from Armour Thyroid to levothyroxine. This request is reasonable and can be done safely under the supervision of a healthcare provider. We’ll cover how and why people make this change in hypothyroidism treatment.

What are the benefits of switching from Armour Thyroid to levothyroxine for hypothyroidism?

Armour Thyroid is derived from desiccated pig thyroids and contains both thyroxine (T4) and triiodothyronine (T3) forms of thyroid hormone. In comparison, levothyroxine sodium is a synthetic product containing only T4, but since the human body converts T4 to T3 naturally, levothyroxine products ultimately result in higher levels of both forms of thyroid hormone. Changing from Armour Thyroid to levothyroxine might be worthwhile from a few standpoints.

Expert guidelines

The American Thyroid Association (ATA) recommends levothyroxine over desiccated thyroid products for the treatment of hypothyroidism. Based on this expert guideline, many doctors and hypothyroid patients prefer levothyroxine over Armour Thyroid.

Product consistency

Using dried porcine thyroid glands to produce the drug may not result in consistent levels of T4 and T3 in Armour Thyroid, according to the FDA. The FDA has not approved Armour Thyroid or a similar product, NP Thyroid. The fear is that if levels of T4 and T3 fluctuate from pill to pill, then adverse effects or suboptimal control of hypothyroidism could result. 

However, a small study of 70 patients showed similar outcomes, more weight loss, and better patient satisfaction with desiccated thyroid extract (DTE) than levothyroxine, meaning that it may have a treatment role in some situations, but further studies are needed. Nonetheless, the FDA has specifically placed a warning on the labels of Armour Thyroid and levothyroxine stating that thyroid hormone products should not be used for weight loss, particularly among people who are euthyroid (have normal thyroid function) because of the dangers of excess thyroid hormone.

Levothyroxine products are FDA approved and standardized. In fact, no significant differences were found between patients in a study who changed their levothyroxine manufacturer and those who did not, even among different manufacturers of generic products. This finding supports the notion that sticking with certain brand-name levothyroxine products, like Synthroid, Levoxyl, or Unithroid, over generic alternatives for reasons of consistency is not always necessary. Based on the perceived consistency among levothyroxine products, endocrinologists tend to favor it over desiccate thyroid extracts like Armour Thyroid.

Adverse effects of desiccated thyroid products

Overtreatment of hypothyroidism entails risk. Too much thyroid hormone can lead to problems like tachycardia, which is an excessively high heart rate that can, in turn, prompt heart arrhythmias or heart attacks among those who are susceptible. A lack of standardization of desiccated thyroid products by the Food and Drug Administration (FDA) was called into question in a study looking at the adverse effects of thyroid hormone extracts like Armour Thyroid. 

Cost savings

Generic levothyroxine can be cheaper than Armour Thyroid, particularly when a SingleCare discount card is used. With a SingleCare coupon for Armour Thyroid, you may pay about $29 for 30, 60 mg tablets. In contrast, levothyroxine costs about $3 for 30, 75 mcg tablets with a SingleCare coupon. Keep in mind that prices will vary among the over 35,000 pharmacies that accept the SingleCare prescription discount card.

Armour Thyroid vs. levothyroxine comparison chart
Armour Thyroid Levothyroxine
Usual dose and frequency 60–120 mg once daily 50–200 mcg once daily
Brand or generic Brand product only Brand and generic products
Active ingredients T4 and T3 T4
Source of hormone Desiccated pig thyroids Synthetic form
Administration guidelines Taken on an empty stomach 30–60 minutes before breakfast Taken on an empty stomach 30–60 minutes before breakfast
FDA approval for hypothyroidism No Yes
ATA recommended No Yes
Retail cost* $56 for 30, 60 mg tablets of brand-name Armour Thyroid $22 for 30, 75 mcg tablets of generic levothyroxine
SingleCare cost* $29 for 30, 60 mg tablets of brand-name Armour Thyroid $3 for 30, 75 mcg tablets of generic levothyroxine
*Cost at time of publication. Drug prices fluctuate and vary by location and pharmacy.

How to switch from Armour Thyroid to levothyroxine

Changing from Armour Thyroid to levothyroxine can be done, but only with the guidance of a healthcare professional. Under their direction, you can typically stop taking Armour Thyroid and replace it with levothyroxine immediately. 

Finding an equivalent dose requires your healthcare provider to do a conversion. Armour Thyroid’s label states that 1 grain of DTE, or 60 mg, contains 38 mcg of T4 and 9 mcg of T3. Based on the body converting T3 to T4 and T3 being more metabolically active than T4, 60 mg of DTE should provide about 74 mcg of effective T4. 

Comparison studies have used 88 to 100 mcg of levothyroxine as a rough equivalent to 60 mg of Armour Thyroid. If the prescribing provider uses this conversion and the patient is taking Armour Thyroid 60 mg, they may have the patient change to levothyroxine 88 mcg.

Regardless of the thyroid preparation you choose to use, it is crucial to take your medication as directed. Armour Thyroid and levothyroxine tablets should be taken on an empty stomach, 30–60 minutes before breakfast. They both interact with similar medications: Neither of them should be taken with calcium, magnesium, iron, or antacid products since they can reduce the absorption of thyroid hormone products.

Side effects from stopping Armour Thyroid and starting levothyroxine

When changing from Armour Thyroid to levothyroxine, the transition may not always be a smooth one. If the healthcare provider overestimates the conversion, the patient could get too much thyroxine and experience symptoms of hyperthyroidism, such as shakiness, palpitations, and diarrhea. The opposite could occur in cases where the patient takes too low of a dose of levothyroxine to replace Armour Thyroid. Examples include constipation, fatigue, and intolerance of cold temperatures.

How to minimize levothyroxine side effects 

Close monitoring is the key to reducing the risk of levothyroxine side effects when switching from Armour Thyroid. Healthcare providers will prescribe a dose of levothyroxine that is estimated to be equivalent to the current Armour Thyroid dose. Blood tests that examine the level of thyroid stimulating hormone (TSH) are then done periodically to assess whether the dose results in a normal thyroid hormone level in the body. Oftentimes, TSH is checked four to six weeks after a medication change and then less often once a given dose is proven effective.

Signs your thyroid medication is working

Symptoms of hypothyroidism should dissipate when thyroid hormone replacement is adequate. Ideally, that means energy levels, temperature regulation, bowel habits, weight, skin moisture, and menstruation will all be normalized, assuming an underactive thyroid was to blame. In reality, though, issues with these elements of our health can come from other problems besides hypothyroidism.

Similarly, you can tell your thyroid medication is working and that you’re taking the right dose if your hyperthyroid symptoms diminish. Examples include tremor, palpitations, heat intolerance, anxiety, weight loss, and diarrhea.

Indicators of abnormal thyroxine levels

If your TSH levels are too low or too high, your healthcare provider will need to adjust your dosage. For example, low TSH levels can indicate that thyroxine levels are too high, meaning that the levothyroxine dose needs to be reduced. Dosing and targeted TSH values may be different in cases of Hashimoto’s thyroiditis-induced hypothyroidism compared to hypothyroidism after thyroid removal for thyroid cancer. 

Conversely, high TSH levels suggest that thyroxine levels are low, which makes the pituitary gland produce more TSH. In that case, the levothyroxine dose may need to be increased. Your primary care provider or endocrinologist will help interpret your symptoms and lab results in order to make a dosing decision.

Bottom line

Switching from Armour Thyroid to levothyroxine may be beneficial for some patients, but not all. If recommended by your healthcare provider, they will need to guide you through the change and monitor its effectiveness afterward. Proper treatment of hypothyroidism can make a world of difference for patients, even if it involves trying different medications.