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Apr 16, 2024

Difference Between Armour Thyroid and Levothyroxine

When it comes to managing hypothyroidism, levothyroxine (synthetic T4) is the established first-line treatment, recognized for its consistent dosage and effectiveness. However, for those who seek an alternative, Armour Thyroid presents another option. Derived from dried pig thyroid glands, Armour Thyroid includes both T3 and T4 hormones.

Understanding the key differences between these treatments can help your discussion with your healthcare provider to choose the most suitable treatment option for you.

Hypothyroidism Overview

Hypothyroidism is a medical condition characterized by an underactive thyroid gland, resulting in insufficient production and release of thyroid hormones.

The thyroid gland, located in your neck, plays an important role in regulating your body's metabolism by producing hormones such as thyroxine (T4) and triiodothyronine (T3). In hypothyroidism, the reduced levels of these hormones can lead to a variety of symptoms, including fatigue, weight gain, sensitivity to cold, dry skin, and mood changes.

According to the American Thyroid Association, it’s estimated that around 5-10% of Americans have some form of hypothyroidism, with women being about 5 to 8 times more likely to develop the condition than men.

The prevalence of hypothyroidism also increases with age, and it’s estimated that up to 20% of women over the age of 60 may have this condition.

Armour Thyroid vs Levothyroxine: Understanding Your Options

Armour Thyroid

Armour Thyroid is derived from dried (desiccated) pig thyroid glands. This means it contains natural forms of thyroid hormones, thyroxine (T4) and triiodothyronine (T3).

The combination of T3 and T4 in Armour Thyroid helps it mimic the function of a healthy thyroid gland more closely than treatments that contain only T4, such as synthetic levothyroxine.

However, it's important to note that Armour Thyroid does not have FDA approval, and its use can sometimes be controversial among medical professionals due to concerns about consistency of hormone concentrations in natural products compared to synthetic alternatives. Despite this, it remains a preferred treatment option for some patients, particularly those who feel they respond better to the natural hormone combination than to synthetic alternatives.


Levothyroxine, also known by the brand name Synthroid, is a synthetic thyroid hormone used for hypothyroidism. It works by supplementing the body's deficient T4 hormone, an inactive form of thyroid hormone that converts into the active T3 form in the body.

By mimicking the body's natural thyroid hormone, Levothyroxine aids in regulating metabolism, energy production, and other critical functions.

Levothyroxine is also used to help prevent and manage goiter, which is an enlargement of the thyroid gland that can occur due to hormone imbalances, radiation therapy, surgeries, or cancer.

Levothyroxine is FDA-approved and widely prescribed for these conditions.

Dosage and Administration

Armour Thyroid

Armour Thyroid is measured in "grains," with 1 grain (about 60 mg) containing 38 mcg of T4 and 9 mcg of T3.

The tablets are available in various doses, ranging from 15 mg (¼ grain) to 300 mg (5 grains).

It’s recommended to take Armour Thyroid on an empty stomach, preferably in the morning, and to separate it from any food intake. This is important as food in your stomach during Armour Thyroid ingestion can impact the absorption.


This medication is available in tablet form, in dosages of 25, 50, 75, 88, 100, 112, 125, 137, 150, 175, 200, and 300 micrograms (mcg), and can be taken by mouth, on an empty stomach, 30 to 60 minutes before breakfast.

It may require around 4 to 6 weeks of Levothyroxine use before the full therapeutic effects become noticeable; however, some may notice an improvement in their symptoms sooner.

Keep using this medication even if you feel well. For those taking this medication for the first time, keep in mind that it could take several months of adjustment and monitoring by your doctor to determine the optimal dosage that’s most appropriate for you.

Side Effects

Both Armour Thyroid and Levothyroxine can cause various side effects, including side effects of having too many thyroid hormones in your body.

Common Side Effects
Armour Thyroid Levothyroxine
  • Nervousness
  • Irritable
  • Fatigue
  • Difficulty sleeping
  • Muscle weakness
  • Shaky hands
  • Increased heartbeat
  • Weight loss
  • Diarrhea
  • Tremors, feeling nervous and/or irritable
  • Fever, hot flashes, sweating
  • Feeling hot/sweating
  • Difficulty sleeping, including insomnia
  • Shortness of breath
  • Chest pain, pain spreading to your jaw or shoulders
  • Fast or irregular heartbeats
  • Weight loss
  • Diarrhea or vomiting

Serious Side Effects
Armour Thyroid Levothyroxine
  • Irregular heartbeat, palpitations, chest pain, or a rapid or irregular heartbeat
  • Chest pain or discomfort
  • Worsening of heart conditions: Armour Thyroid may exacerbate pre-existing heart conditions, especially in those with cardiovascular problems.
  • Adrenal insufficiency: In rare cases, thyroid hormones can suppress adrenal function, leading to adrenal insufficiency.
  • Excessive sweating or sensitivity to heat. Symptoms may indicate an overdose of thyroid hormones.
  • Allergic reactions - symptoms may include rash, itching, swelling, severe dizziness, or difficulty breathing.
  • Difficulty breathing, weakness, tiredness, a swelling in your hands, ankles, and feet
  • Dizziness, lightheadedness, anxiety, fast heartbeat, nausea, cold sweat, clammy skin, chest pain or tightness
  • Hot flashes, fever, or sweating
  • Having memory problems, feeling depressed, or irritable
  • Dryness in your skin or hair, or experiencing hair loss, which is generally temporary and should get better with time.
  • Allergic reactions - symptoms may include rash, itching, swelling, severe dizziness, or difficulty breathing.

If you’re experiencing any of these serious side effects, immediately call your doctor and stop taking this medication.


Levothyroxine and Armour Thyroid each offer different advantages depending on individual needs and responses. Levothyroxine, a synthetic thyroid hormone, is widely recognized as the first-line treatment for hypothyroidism due to its effectiveness and minimal side effects. This makes it a preferred option, especially for pregnant individuals, where the risk of complications with fetal brain development is a significant concern.

Armour Thyroid, derived from porcine thyroid glands, contains both T4 (thyroxine) and T3 (triiodothyronine) hormones in a ratio similar to that produced by the human thyroid gland. This combination might offer advantages for some patients, particularly those who don't convert T4 to T3 efficiently or who have difficulty achieving symptom relief with synthetic T4 alone.

A recent study with 250 participants indicated that those who switched from levothyroxine to Armour Thyroid saw overall symptom improvement. However, it's important to note that a significant number of individuals discontinued Armour Thyroid within the first six months due to side effects and insufficient symptom relief.

When considering Armour Thyroid, it's essential to discuss it with a healthcare provider. This treatment may be particularly beneficial for those who continue to experience symptoms of hypothyroidism despite adequate dosing of levothyroxine, or for patients who prefer a more "natural" thyroid hormone option. Nevertheless, because Armour Thyroid includes T3, which has a rapid action in the body, its effects can be harder to predict and manage, which might explain the higher discontinuation rates observed in some studies.

On the other hand, Levothyroxine provides a consistent and precise dosage of synthetic T4, which is well-tolerated by the majority of patients. Its stability and predictable effects make it a reliable choice for long-term management of hypothyroidism.

Speak with Your Doctor

The decision between Armour Thyroid and Levothyroxine is highly individualized, necessitating a discussion with your doctor. Your healthcare provider will consider various factors, including your health, medical history, and specific symptoms, to create a personalized treatment plan tailored to your needs, ensuring the most effective and well-tolerated approach for managing hypothyroidism.