Does thyroid dysfunction cause hair loss?

The thyroid is a butterfly-shaped gland in your neck. It produces essential hormones and modulates how your body uses energy.

Internal and external factors may disrupt how the thyroid functions. This, in turn, may lead to disturbances in hormone production, causing:

• an underactive thyroid (hypothyroidism) that doesn’t produce enough thyroid hormones to support bodily functions
• an overactive thyroid (hyperthyroidism) that makes more hormones than the body needs

Both conditions may lead to hair loss as well as dry and brittle hair or slowed hair growth.

Why does thyroid dysfunction lead to hair loss?

In brief, thyroid disease is related to hair loss because when there is too much or not enough hormones, the body may need to prioritize some essential functions like healing, making energy, breathing, or heartbeats. Growing new hair does not make the list of essential functions.

Even when prioritizing some bodily processes, thyroid dysfunction may mean your body has difficulty converting food into energy effectively. This may also lead your body to slow or shut down new hair growth.

The first sign of thyroid-related hair loss may be finding more hair on your hairbrush or shower. Due to thyroid dysfunction, hair follicles losing these hairs may not grow new ones, which may lead to thinning across your scalp.

Thyroid disease may also cause:

• thinning eyebrows or hairs missing at the outer edge
• dry, dull, coarse, and brittle hair that easily breaks
• new hair that is of a different texture and thickness, likely finer
• hair that grows quicker or slower than usual
• itchy, dry scalp or dandruff
• balding spots on arms, legs, or other parts of your body

How to know if hair loss is related to the thyroid?

It is natural to lose a few hairs every day. In fact, as part of the hair growth cycle, you typically lose around 50–100 hairs each day. If you lose more hair than this and don’t notice new hair growth, it may signal a health issue, including thyroid dysfunction. 

If your hair loss is related to hypothyroidism or hyperthyroidism, thinning may be spread out evenly across your scalp, as opposed to localized on the crown or specific spots. You may also notice some of the other symptoms listed below.

Hypothyroidism

Depending on its severity, the symptoms of hypothyroidism may include:  

• cold intolerance or feeling cold when others don’t
• constipation
• muscle weakness
• weight gain without a change in eating patterns
• muscle or joint pain
• low mood and fatigue
• dry, pale skin
• a slow heart rate
• sweating less than usual
• puffy face
• hoarse voice
• heavy menstrual bleeding

Hyperthyroidism

The symptoms of hyperthyroidism may include:

• weight loss without a change in eating patterns
• an irregular or fast heartbeat
• irritability, nervousness, and tiredness
• difficulty falling or staying asleep
• muscle weakness or shaky hands
• intolerance to heat or excessive sweating
• frequent bowel movements
• a swollen thyroid gland (goiter)

Untreated hyperthyroidism may lead to a medical emergency known as thyroid storm. Symptoms may include:

• 140 heartbeats or more per minute
• high fever
• confusion
• diarrhea
• shaking and sweating
• loss of consciousness

Only a healthcare professional can help provide an accurate diagnosis. They may explore current symptoms and recommend blood work to measure thyroid hormone production.

Other possible reasons for hair loss

Thyroid disease is not the only cause of hair loss. Other causes may include:

• chronic stress
• chronic conditions
• hormonal changes or imbalances related to childbirth or menopause
• aging, as you may lose more hair as you get older
• nutritional deficiencies like not having enough biotin, iron, or zinc
• autoimmune conditions like Hashimoto’s or alopecia areata
• cancer treatment
• hair dyes, smoothing products, and use of heat
• scalp infections
• hairstyles that pull your hair
• medications that cause hair loss as a side effect
• psoriasis or eczema on your scalp

Your doctor’s examination and a variety of tests may help determine the underlying cause of hair loss.

Treatment for thyroid hair loss

If your hair loss is related to thyroid disease, treating the condition may slow or reverse some of it.

Hypothyroidism

Depending on the severity of your symptoms, your healthcare professional may start you on hormone replacement therapy. This is to replace the hormones your thyroid is not able to make.

Levothyroxine (Synthroid) is the most common medication to treat hypothyroidism. It is a synthetic version of the hormone your thyroid produces naturally.

If your symptoms continue or worsen, your healthcare professional may adjust your dosage. In some cases, getting too much levothyroxine may cause or worsen hair loss.

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Hyperthyroidism

Hyperthyroidism treatment aims to slow down thyroid hormone production and reduce some of the symptoms.

Treatment may include:

• Beta-blockers: These medications are often part of treatment for heart conditions. They do not treat hyperthyroidism directly, but your healthcare professional may use them to reduce related symptoms like nervousness, heat intolerance, and quick heart rate. Doctors often prescribe beta-blockers alongside antithyroid medications. A common beta-blocker for hyperthyroidism is propranolol (Hemangeol).
• Antithyroid drugs: These medications act directly on thyroid hormone overproduction. The most common antithyroid drugs for hyperthyroidism are methimazole and propylthiouracil.
• Radioactive iodine therapy: This treatment involves taking a pill of radioactive iodine-131. It eliminates thyroid cells that overproduce hormones and may also shrink the thyroid gland itself. It is a treatment for severe cases of hyperthyroidism and thyroid cancer.
• Thyroid removal surgery: If other treatments are ineffective or you cannot take antithyroid medications, your health team may recommend removing your thyroid gland, which may permanently treat hyperthyroidism.

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Best vitamins and minerals for thyroid hair loss

Nutritional deficiencies are associated with thyroid dysfunction and other causes of hair loss. But before adding supplements to your routine, confirming those deficiencies is key. Your healthcare professional may want to do bloodwork for this purpose.

Deficiencies in these vitamins and minerals may be associated with thyroid hair loss:

• zinc
• biotin
• vitamins B2, B12, and B9
• vitamin D
• iodine
• selenium
• ferritin and iron

Ensuring you are deficient in these nutrients is essential before supplementing. This is because an excess of some of these may worsen your symptoms, including hair loss.

Will hair grow back?

Once you treat the underlying cause of thyroid hair loss, this may resolve. It may take several months for hair loss to slow down and new hair to grow.

The hair growth cycle may take at least 150 days, so you may start noticing new hair after a few months of treatment.

Other strategies may also help this process, including:

• exploring and treating nutritional deficiencies with your healthcare team
• following an anti-inflammatory diet
• using hair care products designed for hair growth
• trying red light stimulation
• asking your healthcare team about supplements like saw palmetto and black seed oil

Summary

Thyroid dysfunction may cause diffuse hair loss. Both an underactive thyroid (hypothyroidism) and an overactive thyroid (hyperthyroidism) may lead to overall thinning and dry and brittle hair.

Thyroid treatment can help slow hair loss and promote new hair growth, but it may take months.

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