Your Thyroid and Hair Loss: Solving the Problem

Checking hair in mirror

Your hair is a fairly accurate barometer of your health. Hair cells are some of the fastest growing in the body, and when your body is under stress or in crisis, hair cells can shut down in order to redirect energy to places where it is more needed. The types of physical situations that can cause hair loss include hormonal changes, nutritional deficiencies, a variety of medications, surgery, and many medical conditions, in particular, thyroid disease.

Hair Loss Is Common

Hair loss is actually fairly common. According to the American Academy of Dermatology, nearly half of all adults in the U.S. will experience thinning hair by age 40. But thyroid patients, in particular, often experience hair loss earlier and more rapidly than usual.

Normally, hair grows about a half inch a month for about 3 years, and then it goes into a resting period. One in 10 of your hairs is in a resting period at any one time. After about 3 months, a new hair pushes the old one out. When more hairs go into resting period, or the process speeds up, the balance becomes disrupted and you may notice increased hair loss.

Hormones and Your Hair

Hormonally-induced hair loss takes place when an enzyme starts to convert the hormone testosterone to its less useful version, dihydrotestosterone, or DHT. DHT then attacks your hair follicles and shrinks them, even making follicles disappear entirely.

Your hair can become thinner and finer and may stop growing. This conversion of testosterone to DHT seems to be sped up in some patients with hyperthyroidism or hypothyroidism. This may be the cause of hair loss that continues for thyroid patients, even if your doctor says you are receiving adequate thyroid treatment.

Hair Loss and Your Thyroid

In some cases, you may feel that rapid hair loss is the worst symptom of your thyroid problem. It can be frightening to notice thinning hair, large amounts of your hair falling out in the shower or sink. You may also be concerned about changes in your hair's texture, noticing that it has become dry, coarse, or tangles easily. In some cases, your thyroid problem may even be first suggested by your hairdresser, after noticing changes in your hair.

While thyroid disease frequently causes general hair loss from the hair on the head, a unique and characteristic symptom of hypothyroidism is the loss of the hair on the outer edge of your eyebrows. If you have lost eyebrow hair, this can be a sign of undiagnosed or poorly treated hypothyroidism. General loss of body hair from areas other than your head can also be seen in thyroid disease.

Steps to Overcome Hair Loss

If you have a thyroid condition and are concerned about the amount of hair you are losing, here are some steps to take:

  • Get evaluated by a dermatologist. Even if you are in the midst of dealing with a thyroid problem, it's still a good idea to see a dermatologist. A good dermatologist experienced in hair loss can do a complete workup in order to assess the causes of your hair loss and run tests that may identify other autoimmune conditions besides thyroid that may cause hair loss. For a hair loss specialist, visit or contact the American Academy of Dermatology, who can provide a referral to a dermatologist in your area.
  • Make sure it's not your thyroid drug. If you are taking levothyroxine (i.e., Synthroid, Levoxyl, Unithroid, Levothroid, Tirosint) as your thyroid hormone replacement, and still losing hair, you may need to take action. Prolonged or excessive hair loss is a side effect of these drugs for some people. Note: Many doctors do not know this, even though it is a stated side effect in the Synthroid patient literature, for example, so don't be surprised if your doctor is not aware of this.
  • Make sure you're not undertreated. Hair loss can also result from being undertreated, not being at the right TSH, or not taking the right thyroid medication for you. An increasing number of doctors believe that a TSH of around 1.0-2.0 is optimal for most people to feel well and avoid having hypothyroid or hyperthyroid symptoms such as hair loss. (Note that these levels are kept lower for thyroid cancer patients to prevent cancer recurrence.)
  • Find out if you need a second drug: Some people on levothyroxine drugs like Synthroid, Levoxyl, or Tirosint find that they have less hair loss when they switch to a T4/T3 combination therapy. This can be accomplished by adding a T3 drug like Cytomel to levothyroxine therapy, or in some cases, switching to a natural desiccated thyroid (NDT) drug like Armour Thyroid or Nature-throid. Some studies have shown that some patients feel and do better on a combination of T4 and T3, not T4 (i.e., levothyroxine drugs like Synthroid) alone.
  • Consider replacing levothyroxine with another medication. Some people on levothyroxine drugs experience temporary or permanent hair loss—a side effect reported in the prescribing instructions—while on this drug. You may want to ask your practitioner about replacing levothyroxine treatment with an NDT drug, to determine if it helps reduce hair loss.
  • Have ferritin evaluated and treated if needed. Having sufficient iron is important for hair health and growth. Of particular importance is your level of ferritin, the stored form of iron. Ask your practitioner to evaluate your ferritin. Some practitioners feel that levels in the top 20th percentile of the reference range are optimal for helping to minimize hair loss. If your levels are not optimal, talk to your doctor about supplementing with iron. (Remember not to take iron within three hours of your thyroid medications.)
  • Consider evening primrose oil. Some naturopathic and holistic practitioners recommend that you take evening primrose oil (also known as EPO), to help with hair loss. EPO, a source of essential fatty acids, acts as a weaker form of the drug finasteride (Propecia), and helps inhibit the conversion of testosterone to dihydrotestosterone.
  • Consider other supplements. In one study, Dr. Hugh Rushton, a professor at Portsmouth University, found that 90 percent of women with thinning hair were deficient in iron and the amino acid lysine. Lysine helps transport iron and is the most difficult amino acid to get enough of via your diet. Some other supplements that may help with hair loss include pantothenic acid, saw palmetto, vitamin B6, and zinc.
  • Consider a drug treatment. In some cases, your doctor may recommend that you try a drug treatment. The two popular drugs for hair loss—minoxidil (Rogaine) and finasteride (Propecia)—both interfere with DHT's ability to destroy hair follicles. Neither drug is safe to use during pregnancy, however, and so they are not as commonly used in women of child-bearing age. Rogaine is available without a prescription at lower strengths, and higher-strength versions are available by prescription. Improvements with minoxidil are slow; it may take months for you to see any slowing of hair loss and a year or more for any dramatic change in hair loss and regrowth. To maintain improvements, minoxidil also needs to be continued daily. Finasteride is a prescription drug taken in pill form. It is not to be used by women in their childbearing years because of its ability to cause serious birth defects. Finasteride does not, however, appear to be any more effective than minoxidil, and like minoxidil, it can take a year to see results and must be taken continuously to maintain regrowth.

A Word From Verywell

If you've been checked out by the dermatologist and determined to have thyroid-related hair loss, you will have to be patient. It's likely that for most of you, your hair loss will slow down and eventually stop once your thyroid hormone levels are optimized. This can take a few months, however. In the meantime, hair thickening products, a change of style, hair extensions, or other approaches may help you look your best.


American Hair Loss Association Website. Online:

Cheung EJ, et al. "Vitamin and Mineral Deficiencies in Patients With Telogen Effluvium: A Retrospective Cross-Sectional Study." J Drugs Dermatol. 2016 Oct 1;15(10):1235-1237. Database. "Propecia/finasteride."  Online