Armour Thyroid: How It Works, Dosage, Side Effects, Interactions, and More

Last Updated on

Hypothyroidism is a common health problem characterized by the underactive thyroid gland.

Although a cure for hypothyroidism does not truly exist yet, it is possible to manage it and keep the symptoms associated with this condition under control.

Your doctor will likely primarily treat your underactive thyroid by supplementing the thyroid hormone your gland cannot produce on its own[i].

Different medications are used for this purpose, including Armour Thyroid, Synthroid/Levothyroxine, and Cytomel. Chances are high you have already heard of this drug. This post aims to provide valuable information you should know about Armour Thyroid.


Armour Thyroid is the brand name for a hormone used to address problems associated with underactive thyroid.

It belongs to the group of desiccated thyroid hormones or products which use dried, crushed animal glands (usually porcine or bovine) to replace or support the production of thyroid hormones.

The animal glands are dried or desiccated, ground to powder, and combined with chemicals that serve as binders. The mixture is then pressed into pills.

While bovine glands were used back in time as well, nowadays porcine thyroid is most commonly utilized.

The history of desiccated thyroid starts in 1891 when George Redmayne Murray, an English physician discovered the treatment while attempting to cure a patient with myxedema, a very severe form of hypothyroidism. Through a series of injections of sheep thyroid extract, he saved the life of the patient[ii].

The treatment was quickly adopted by doctors from North America and the United States.

Desiccated thyroid use has become one of the most effective treatments of hypothyroidism, before the middle of the 20th century, primarily because these medications were able to treat a multitude of symptoms.

Back then, there were no accurate laboratory tests that could help someone, but the decision to treat hypothyroidism with this natural ingredient depended greatly upon someone’s symptoms.

The absence of laboratory tests prevented some individuals who had hypothyroidism from receiving necessary treatment.

In the 1960s, desiccated thyroid medications was slowly replaced by levothyroxine (T4) or by a combination of T3 and T4.

Surprisingly, the replacement of medications happened faster in the US than in the UK. By 1980s more patients were prescribed with T3/T4 combination or levothyroxine.

Although levothyroxine is more popular today, desiccated thyroid use keeps increasing as some patients believe it to be more effective than synthetic hormones.

Medical use

The most common use of Armour Thyroid is to function as a replacement or supplemental therapy for patients who are diagnosed with hypothyroidism of any form.

The only exception here is transient hypothyroidism (abnormal levels of T4 or TSH are found on initial screening, but subsequent testing shows normal amounts) during the recovery from subacute thyroiditis.

Subacute thyroiditis is an immune reaction of the thyroid gland that usually follows an upper respiratory tract infection.

Armour Thyroid can also benefit patients diagnosed with[iii]:

  • Myxedema – severe hypothyroidism
  • Cretinism – a congenital disease due to deficiency or absence of normal thyroid secretion, indicated by physical deformity, dwarfism, and mental retardation
  • Euthyroid goiters – swollen thyroid gland in the neck
  • Hashimoto’s disease (chronic lymphocytic thyroiditis) – an autoimmune disease, the immune system attacks the thyroid gland, thus causing hypothyroidism
  • Thyroid cancer – occurs in the cells of thyroid


When it comes to hypothyroidism medications, the dosage is always individualized for every patient depending on his/her laboratory findings, medical condition, and response to treatment.

For children, the daily dose depends on weight and age.

Armour Thyroid is taken by mouth as directed by your physician, but it’s usually once a day on an empty stomach 30 minutes to 1 hour before breakfast. Most patients prefer to take it as soon as they wake up.

You should adhere to the provided dosage instructions and stay away from adjusting it on your own.

The medication comes in different strengths including 15, 30, 60, 120, 180, 240, and 300 milligrams.

Here are the most common dosages for different uses of Armour Thyroid.


The starting dose is 30-32.5mg a day on an empty stomach. To help you achieve adequate serum T3 and T4 levels, the doctor may increase the dose by 15-16.25mg every two to three weeks. The maintenance dose is 60-130mg a day.

Thyroid cancer

In the case of follicular and papillary carcinoma of the thyroid patients need larger doses and they usually go from 30mg to 120mg per day.

Pediatric dose

As mentioned above, the dosage of Armour Thyroid for children is determined by their body weight. The table below demonstrates the typical dosages for children of different ages.

AgeDaily dose per kg of body weightDose per day
0-6 months4.8-6mg15-30mg
6-12 months3.6-4.8mg30-45mg
1-5 years3-3.6mg45-60mg
6-12 years2.4-3mg60-90mg
Over 12 years1.2-1.8mgOver 90mg


Make sure you never miss a dose and always strive to take the recommended amount, even if you think it’s not enough.

Your doctor will increase the dosage when it’s the right time for it.

Taking more than recommended can lead to overdose. If this happens, contact 911 or Poison Control center at 800-222-1222.

How does it work?

Armour Thyroid works to replace the thyroid hormone in instances when the body does not produce sufficient amounts of hormones on its own. The medication is formulated as a natural blend of T3 (triiodothyronine) and T4 (thyroxine). Treatment with Armour Thyroid can optimize levels of TSH, T3, and T4 probably to the same extent as Synthroid, a common medication used for hypothyroidism.

Armour Thyroid and Synthroid are usually compared to one another, but the latter is a synthetic version of the drug. It is also important to mention that unlike its counterpart, Armour Thyroid has never been formally approved by the FDA.

The scientific data about Armour Thyroid is scarce, but a study whose findings were published in the Journal of Clinical Endocrinology and Metabolism found that desiccated thyroid extract could be relevant for some hypothyroid patients[iv]. In fact, it had similar efficacy to levothyroxine.


To minimize the risks associated with medications, it is important to inform your doctor about all prescription and nonprescription drugs you are using at that point.

Ask whether Armour Thyroid is safe for you if you are taking medications for some other health condition.

According to, Armour Thyroid interacts with 569 drugs including[v]:

  • Alprazolam (Xanax)
  • Aspirin
  • Birth control pills
  • Blood thinners such as warfarin
  • Cetirizine (Zyrtec)
  • Clonazepam
  • CoQ10
  • Dehydroepiandrosterone (DHEA)
  • Digoxin, insulin, or other oral medications for diabetes
  • Duloxetine (Cymbalta)
  • Estrogen
  • Gabapentin
  • Hydrochlorothiazide
  • Lisinopril
  • Metformin
  • Omega-3 fatty acids
  • Omeprazole
  • Pregabalin (Lyrica)
  • Progesterone
  • Tramadol
  • Trazodone
  • Vitamin B12
  • Vitamin C
  • Vitamin D3

IMPORTANT: You should avoid taking colesevelam (Welchol), colestipol (Colestid), or cholestyramine (Questran) within 4-5 hours of taking Armour Thyroid.

Patients who are taking sucralfate (Carafate) and orlistat (Xenical) should consult their healthcare provider regarding the use of these medications with Armour Thyroid.

Besides a vast spectrum of medications, Armour Thyroid can also interact with some health conditions including:

  • Adrenal insufficiency
  • Cardiovascular disease
  • Diabetes
  • Seizures
  • Thyrotoxicosis

Side effects

During the first few months of the thyroid treatment, hair loss may occur. In most instances, the effect is temporary and goes away once the body adjusts to the drug.

Of course, if this side effect persists, consult your doctor or pharmacist.

While medications are formulated to provide relief, they do have some adverse effects.

When it comes to Armour Thyroid, side effects may be caused by an active ingredient, thyroid desiccated and the risk increases when patients increase the dosage without consulting their healthcare provider first.

Below, you can find the list of side effects associated with Armour Thyroid:

  • Allergic reaction to ingredients in Armour Thyroid (hives, rash, difficulty breathing, itching, swelling of the mouth, tongue, or face, tightness in chest)
  • Changes in appetite
  • Changes in menstrual periods
  • Chest pain
  • Diarrhea
  • Excessive sweating
  • Fast or irregular heartbeat
  • Fever
  • Hand tremors
  • Headache
  • Irritability
  • Leg cramps
  • Nervousness, mood swings
  • Sensitivity to heat
  • Shortness of breath
  • Trouble sleeping
  • Unusual weakness
  • Vomiting
  • Weight loss

If you experience these symptoms, get emergency help immediately. It is highly important to consult your healthcare provider rather than experimenting with the dosage on your own.


Despite the fact that Armour Thyroid is considered a natural type of medication because it focuses on animal thyroid gland rather than synthetic ingredients, some experts consider it a bit controversial.

Some doctors seldom prescribe Armour Thyroid primarily because they consider it an antiquated therapy that should not be used any longer.

These endocrinologists and physicians claim that desiccated thyroid medications such as Armour Thyroid should have no role in treating hypothyroidism.

These drugs are not discussed in many medical books and it is not uncommon for healthcare providers to think these medications aren’t available on the market anymore[vi].

Another important reason why endocrinologists avoid prescribing Armour Thyroid to patients is an due to a degree of variability from batch to batch. Oftentimes this results in TSH fluctuations, which is also unacceptable.

Those who oppose Armour Thyroid also explain that although variations are present with different batches and products of levothyroxine, if we compare them, natural desiccated thyroid hormone exhibits greater fluctuations,[vii] although this has improved since then.

While many endocrinologists and physicians avoid prescribing Armour Thyroid to their patients, others believe the medication can be helpful.

In a recent double-blind, randomized research study, a great deal of patients greatly preferred natural desiccated thyroid extracts when compared to Synthroid/Levothyroxine.


Armour Thyroid is a natural medication used to treat hypothyroidism and other conditions affecting your thyroid gland and production of hormones.

Unlike synthetic versions, Armour Thyroid is a natural desiccated hormone made from dried thyroid gland of a pig. Dosage depends on a person’s condition and other factors.

While some patients greatly prefer Armour Thyroid when compared to other thyroid treatments, Armour Thyroid is not often prescribed by doctors (Synthroid is the most common thyroid treatment).

A patient will usually have to seek out a doctor that prefers Armour Thyroid or actively ask to be prescribed the medication.


[i] Hypothyroidism, American Thyroid Association

[ii] Murray GR. Note on the Treatment of Myxœdema by Hypodermic Injections of an Extract of the Thyroid Gland of a Sheep. British Medical Journal. 1891;2(1606):796-797.

[iii] Armour Thyroid: Indications and Dosage,

[iv] Hoang TD, Olsen CH, Mai VQ, Desiccated thyroid extract compared with levothyroxine in the treatment of hypothyroidism: a randomized, double-blind, crossover study. The Journal of Clinical Endocrinology and Metabolism,  2013 May;98(5):1982-90. Doi: 10.1210/jc.2012-4107

[v] Armour Thyroid (thyroid desiccated) Drug Interactions,,armour-thyroid.html

[vi] Grozinsky-Glasberg S, e. (2017). Thyroxine-triiodothyronine combination therapy versus thyroxine monotherapy for clinical hypothyroidism: meta-analysis of randomized controlled trials.

[vii] My Thyroid.

1 Comment
  1. Reply
    Jacqueline August 6, 2021 at 4:54 pm

    Wow, those dosage levels are way too low. The Armour starting dose should be 90 mg and then move up or down from there. A person taking 30 mg would not feel any different. No wonder so many people in the U.K.think Armour doesn’t work – they’re not taking nearly enough.

    Leave a reply