Hypothyroidism Hair Loss

How Hypothyroidism Affects the Hair Growth Cycle

Hair doesn’t just keep growing and growing. At some point, it falls out. 

This is all a natural part of the hair growth cycle — each hair follicle goes through phases of growth (anagen), transition (catagen), rest (telogen), and shedding (exogen) before coming full circle back to growth.

An underactive thyroid doesn’t produce enough hormones to keep the hair follicles happy and the growth cycle on track. 

Instead, this hormonal shortfall prolongs the telogen phase, causing more hairs to rest and shed than usual — hello, hypothyroidism hair loss.

Hypothyroid hair loss isn’t patchy. You won’t end up with sudden bald spots. Instead, the hair shedding is diffuse, meaning it thins evenly across the scalp. 

But it’s not just the hair on your head that’s affected. Yep, hypothyroidism and eyebrow hair loss are connected too! 

Hypothyroidism can cause eyebrow hair thinning, especially at the outer third of the eyebrows in a look that’s often called the Queen Anne sign.

If you’re noticing these changes, it’s a good idea to consult your doctor. They can assess your thyroid function and guide you toward effective treatments to help restore your hair’s health.

Causes of Hypothyroidism Hair Loss

Low thyroid hormone levels

In 2008, researchers provided the first evidence that thyroid hormones affect hair follicles. 

They found that the thyroid hormone thyroxine (T4) extends the growth phase of the hair growth cycle — possibly because it suppresses a protein that’s known to inhibit hair growth (called transforming growth factor-beta 2 or TGF-β2).

Their theory: 

When thyroxine levels are low, as they are in hypothyroidism, it allows that TGF-β2 protein to run wild, prolonging the resting (telogen) phase of the hair growth cycle and causing hypothyroidism hair loss.

So low levels of thyroid hormones are the main cause of hair loss from hypothyroidism. But sometimes hypothyroidism is a sign of a deeper problem. 

Autoimmune conditions

Hypothyroidism can be a symptom of Hashimoto’s thyroiditis, an autoimmune condition where the immune system attacks the thyroid gland, impairing its ability to produce hormones. 

People with autoimmune thyroid diseases like Hashimoto’s thyroiditis and Graves’ disease are also more likely to present with the autoimmune hair loss condition alopecia areata. 

In fact, many studies show that people with alopecia areata also have a thyroid disease, indicating a possible link between the two. 

For example, studies of people with alopecia areata generally find that up to 28% of cases also have thyroid disease. On the other hand, a Turkish study of almost 700 people with thyroid disease (both autoimmune and non-autoimmune) found that 4.1% of patients had alopecia areata. 

Other autoimmune diseases that may be linked to hypothyroidism and hair loss include polycystic ovary syndrome and lupus erythematosus. 

Medications

Finally, we can’t look at the causes of hypothyroidism hair loss without mentioning medications. In rare cases, some antithyroid drugs like carbimazole and propylthiouracil may cause hair loss.

The Signs and Symptoms of Hypothyroidism Related Hair Loss

Thyroid hormones affect nearly every hair follicle on your head simultaneously. So you won’t see the telltale signs of genetic hair loss, like a receding hairline, bald patches, or widening part. And it won’t be dramatic or sudden. 

Instead, the hypothyroidism hair loss pattern is quite simple: gradual, diffuse hair thinning across the entire scalp. This can make it harder to notice at first, as the change is subtle over time. Your ponytail might feel thinner, or you might see more hair in the shower drain than usual.

Beyond the amount of hair you’re losing, hypothyroidism can also change the hair that remains, making your once-luscious locks brittle, coarse, dry, dull, and prone to breakage. 

These texture changes happen because thyroid hormones help regulate the production of oils that keep your hair healthy and moisturized. When these hormonal levels are low, your hair loses its natural protection and resilience.

Even when your hormonal levels stabilise, your hair won’t immediately return to its former glory. 

Hair regrowth follows its own slow timeline. The delayed response occurs because hair follicles need time to transition back into their growth phase of the hair growth cycle. 

It may take a few months —  about 3–6 months — for your hair to catch up as your body adjusts to the treatment.

Diagnosing Hypothyroidism and Hair Loss

It’s important to get a proper diagnosis if you’re concerned about your hair loss, especially if a thyroid issue could be the underlying cause. 

Diagnosing hypothyroidism and hair loss usually begins with a medical history (including whether there’s a family history of thyroid conditions or hair loss) and a physical examination. 

Your doctor will be looking for other symptoms of thyroid disorder, such as fatigue, cold intolerance, weight changes, and dry skin. 

They may also request a blood test to check your hormonal levels while helping to rule out other causes, such as nutritional deficiencies. These are some of the things they will look for:

• High TSH (Thyroid Stimulation Hormone) — this indicates that your body is trying to stimulate more thyroid hormone production as a result of an underactive thyroid.
• Low free T4 (Thyroxine) — This means there are lower levels of thyroxine circulating in your blood stream, confirming hypothyroidism. 

• Low free T3 (Triiodothyronine) — As with low free T4, low levels of the active form of the thyroid hormone suggests hypothyroidism.
• Thyroid antibodies — Tests like TPO (thyroid peroxidase) antibodies can identify autoimmune conditions like Hashimoto’s thyroiditis, a common cause of hypothyroidism.

In more severe or persistent cases of hypothyroid hair loss, your doctor may also recommend more rigorous diagnostic tests:

• Dermoscopy — A non-invasive examination using a special magnifying tool to assess hair shaft quality and follicle health.
• Scalp biopsy — In rare cases, doctors may remove a tiny sample of scalp tissue to examine hair follicles under a microscope.
• Trichogram — A procedure where a small number of hairs are extracted and examined to determine the percentage in different growth phases.

How to Stop Hypothyroidism Hair Loss

Treating thyroid-related hair loss is all about addressing the root cause — the hormonal imbalance. Boosting T3 and T4 levels may be enough to reverse the hair loss. 

The single most effective way to stop hair loss from hypothyroidism is through medication. Most people are prescribed thyroid hormone replacement therapy — usually levothyroxine, which is a type of synthetic T4. We’ll look at it in more detail below. 

You may also like to complement this medication with a few lifestyle changes for hair health, such as:

• Stress management — Chronic stress elevates cortisol, which can further disrupt the hair growth cycle. Stress reduction techniques include mindfulness meditation, breathwork, and yoga.
• Gentle hair care practices — Some hair practices put further stress on your hair. Minimise heat styling, harsh chemicals, and tight hairdos.
• Regular physical activity — Exercise improves blood circulation to the scalp and helps regulate hormone levels.
• Adequate sleep — Sleep is essential for cellular repair and hormonal regulation. Try to get 7–8 hours of sleep every night.
• Hydration — Drinking enough water supports nutrient delivery to hair follicles. Aim for 2 litres of water per day.

Hypothyroidism is a chronic disease, which means it requires ongoing attention. This may involve:

• Regular blood tests to monitor TSH and thyroid hormone levels
• Dosage adjustments as needed to keep the levels balanced
• Regular communication and follow-up appointments with your doctor or endocrinologist about persistent symptoms

With the right medical treatment and some simple lifestyle changes,  you have a good chance of stopping hypothyroidism hair loss.

But it’s important to manage expectations — thanks to the nature of the hair growth cycle, it may take a few months to notice any improvements in your hair.

Hypothyroidism Hair Loss Treatment Options

Let’s take a deeper look at some of the treatment options available for hypothyroid hair loss, from medications to hair growth products. 

Hormonal Replacement Therapy (HRT)

When we talk about thyroid HRT, we’re usually talking about levothyroxine. This is a synthetic hormone that compensates for the thyroid’s underactivity and has been proven to reverse the effects of hypothyroid hair loss.  

Levothyroxine jumps in where your body leaves off, helping to produce the thyroid hormones you need. As these hormone levels stabilise, your hair follicles gradually shift from their dormant state back into active growth phases.

Levothyroxine is just a single pill taken daily, usually taken on an empty stomach. 

Topical Treatments for Hair Regrowth

For those experiencing severe or persistent hair thinning even after your thyroid levels have improved, a topical hair loss treatment option may give your hair follicles an additional boost. 

Minoxidil can be particularly helpful for thyroid-related hair loss. Applied directly to the scalp, minoxidil helps increase blood flow to the hair follicles, boosting the amounts of oxygen and nutrients they receive. 

Many endocrinologists and dermatologists recommend minoxidil as an adjunct therapy when thyroid medication alone just isn’t doing the job, hair-wise. 

You’ll need to apply it consistently for at least 3–6 months before you start seeing any noticeable improvements.

Nutritional Support for Hair Health

Medication addresses the underlying cause of hypothyroid hair loss but vitamins and minerals are also essential for hair health. Make sure you get enough of your daily needs through a nutrient-rich diet (including plenty of good foods for hair health).

Your doctor may recommend blood tests to identify specific nutritional deficiencies and suggest targeted nutritional supplements alongside a nutrient-dense diet. 

There are a few vitamins and minerals that are particularly important for hair health, including:

• Iron — Essential for hair follicle function and often depleted in thyroid patients
• Zinc and selenium — Minerals that support thyroid function and hair structure
• B vitamins — Particularly biotin (B7) and B12, which are vital for healthy hair development
• Protein — Supplies the amino acids that give hair its elasticity and strength
• Omega-3 fatty acids — Help reduce inflammation that may impact hair follicles

Thickening Shampoos and Conditioners

Yes, hair thickening shampoos and conditioners do exist, although the jury’s out on how effective they are. 

Most experts recommend simply using a mild, natural shampoo free from sulphates but you can also look out for shampoos that contain herbs that are good for hair growth, such as lavender or rosemary oil. 

Hair Fibers and Powders

Hair powders are coloured keratin fibres that bind to your hair and make it look fuller and thicker. 

But compared to other hypothyroidism hair loss treatment options, it doesn’t match up for one simple reason:

It disguises hair loss — it doesn’t treat it. 

One 2017 study of patients receiving trichology treatment found that hair fibres were effective in hiding hair loss. But if you’re looking for a solution that treats the cause of the problem, look elsewhere. 

Hair Accessories

Overnight cures for hair loss don’t exist. But cosmetic options do! If you’re feeling insecure about your hair thinning or hair loss, you can try wearing a headband, scarf, or wig to help disguise thinning areas while adding style to your look.

Does Stress Affect Hypothyroidism Hair Loss?

Chronic or severe stress doesn’t just affect your mental wellbeing. It can flood your system with cortisol, which can interfere with thyroid hormone production and affect hair growth. 

There are plenty of studies that back this up. 

A cross-sectional Indian study of 114 women found that higher stress levels often corresponded with mildly higher TSH levels (an indicator that your thyroid isn’t producing enough hormones).

Meanwhile, a 2024 literature review concluded that chronic stress can have a big impact on the endocrine system, creating a triiodothyronine (T3) deficiency that may lead to thyroid dysfunction. 

Prolonged or severe stress can also trigger a type of hair loss called telogen effluvium, which leads to increased hair shedding and may exacerbate hair loss if you already have a hormonal imbalance. 

Many endocrinologists now recognize this interplay between stress and hair loss and may recommend stress reduction techniques alongside more conventional thyroid treatments.

Some relaxation techniques might include mindfulness medication, breathwork, gentle yoga practices, regular exercise, and anything that might help relax your muscles.

Best Haircare Practices for Hypothyroidism

While you’re on a treatment plan, you might want to take care of the hair that’s already there — and the strands that are starting to regrow. 

Hair impacted by hypothyroidism can be brittle so a gentle haircare routine can help prevent further damage and create the right conditions for new hair:

• Detangling your hair with a wide-tooth comb, starting from the ends and working up. 
• Avoid brushing wet hair — this is when it’s least elastic and prone to breaking.
• Pat your hair dry with a microfibre towel instead of rough towel-rubbing.
• Use scrunchies or fabric-covered elastics instead of rubber bands when tying hair back.

• Sleep on a silk or satin pillowcase to reduce friction and moisture loss.
• Limit hair washing to 2–3 times weekly unless your scalp is particularly oily.
• Let your hair air dry rather than using the hair dryer — and keep heat styling tools below 150 degrees Celsius. 
• Let your hair down wherever possible and avoid tight hairdos. 
• Avoid harsh chemical treatments like colouring or bleaching your hair — at least until your thyroid levels stabilise.

When to See a Doctor?

Whenever you’re concerned about hair loss, you should consult a doctor. They can assess your medical history, examine your scalp, and order blood tests to identify the root cause of your hair loss. 

If you’re already taking treatment for hypothyroidism and your hair loss persists or worsen, it’s worth talking to a doctor. Sudden or severe hair shedding may suggest that there’s another underlying issue that needs medical attention.

FAQs

1. Can adjusting my thyroid medication dosage help with hair regrowth?

Levothyroxine comes in a range of dosages and the dose you’ll be described will depend on your unique situation. Most people start on the same dose but over time, the doctor may increase your dose based on how well your body responds to the medication. 

Adjusting the dose of your thyroid medication may help with hair regrowth but it’s a careful balancing act: you may experience side effects if you end up taking more thyroid medication than your body needs — and rather counterproductively, hair loss can be one of those side effects. 

2. Can biotin or other supplements help with hypothyroidism hair loss?

If you want to give your hair a bit of a boost with supplements, we recommend staying clear of biotin. 

For a start, it has no effect on thyroid hormone levels or thyroid function. But more importantly, a study by the American Thyroid Association found that biotin supplements can falsely change the result of a blood test for TSH, Free T4, total T3, and thyroglobulin — all important measures when diagnosing hypothyroidism.

If you’d like to know what supplements may help with hair loss, read our complete guide to hair growth supplements. 

3. What foods help prevent or reverse hypothyroidism hair loss?

According to the British Thyroid Foundation, there’s no specific diet that will help with hypothyroidism (although it’s worth noting that certain foods interact with the thyroid medication levothyroxine and should be avoided in the hours after taking medication).

While there’s no evidence that a specific diet helps with hypothyroidism hair loss, certain foods do contain the vitamins and minerals essential for healthy hair. These include egg, sweet potato, avocado, red meat, and fatty fish. 

If you want to know more, read our breakdown of the best foods for hair health. 

4. Can extreme dieting or fasting trigger more hair loss in people with hypothyroidism?

Short answer: yes. In general, extreme diets, such as the keto diet, can deprive your hair follicles of the essential nutrients, calories, and proteins needed for hair growth. 

The extra stress on the body can cause hair loss — not a good thing if you’re already struggling with hair loss from hypothyroidism. 

Fasting can also affect thyroid hormonal levels. A 2021 review of hormonal levels during fasting noted that multiple studies saw T3 levels in patients decrease rapidly after fasting.

One study of 64 hypothyroidism patients during Ramadan found that intermittent fasting elevated TSH levels — remembering that high TSH indicates an underactive thyroid. 

If you’d like to learn more, read about the impact of the keto diet on hair growth. 

5. Can a gluten-free diet help reduce hair loss in people with hypothyroidism?

In recent years, researchers have consistently concluded that there’s not enough evidence to support the idea that a gluten-free diet could help with hypothyroidism (and, by extension, hypothyroid hair loss). 

These include findings from a 2020 literature review, a 2021 twelve-month study, and a 2022 literature review. 

If you’re concerned, it’s best to speak with a medical practitioner who can assess you for coeliac disease or gluten sensitivity.