Can thyroid problems cause hair loss?
Yes. Your thyroid gland controls how fast your body uses energy, and hair follicles are among the busiest cells in the body. When thyroid hormone levels are too low or too high, more hairs move into the resting stage and shed, and the hair that grows can be drier or finer.
Thyroid problems are common, especially in women, and easy to miss: tiredness, weight change and low mood are often put down to a busy life, a new baby or the menopause. Hair loss is sometimes the change that makes people ask for a test.
The short answer
Both an underactive and an overactive thyroid can cause hair loss, usually thinning all over the scalp rather than patches. A simple blood test through your GP checks your thyroid. Once your levels are back in range, the shedding usually settles and the hair grows back, though it takes several months.
Signs of thyroid hair loss
- Thinning all over the scalp, rather than in patches
- More hair than usual in the shower, on your brush and pillow
- Hair that feels dry, coarse and brittle (underactive thyroid) or fine and soft (overactive thyroid)
- Hair that seems to grow more slowly
- Thinning of the eyebrows, sometimes at the outer ends
Thinning eyebrows can have other causes too, so they’re a clue rather than proof.
Other symptoms to mention to your GP
Underactive thyroid (hypothyroidism): tiredness, feeling cold, weight gain, constipation, dry skin, low mood, heavy or irregular periods.
Overactive thyroid (hyperthyroidism): weight loss, feeling hot, a racing heart, shaky hands, anxiety, difficulty sleeping.
After having a baby, some women develop postpartum thyroiditis, which can swing from overactive to underactive in the first year. Postpartum hair loss.
Testing your thyroid
Your GP can check your thyroid with a blood test. It usually measures TSH (thyroid-stimulating hormone), often with free T4. Sometimes T3 or thyroid antibodies are checked too, for example to look for Hashimoto’s thyroiditis.
When I see someone with diffuse thinning, I often suggest iron stores and vitamin D are checked at the same time, as low iron is common with thyroid problems and adds to shedding. Blood tests for hair loss.
A borderline result is worth repeating after a few weeks, as levels can change. If you already take thyroid medication, bring your latest results to your consultation.
Will my hair grow back after thyroid treatment?
Usually, yes. Thyroid hair loss doesn’t damage the follicles. Once your thyroid levels are stable and in range, shedding normally settles over three to six months, and new growth follows. Hair grows about a centimetre a month, so it can take a year or more to look full again.
- Get the levels right. Treating the thyroid is the most important step. It can take a few months, and several dose changes, to get there.
- Check iron and vitamin D, and put right anything that’s low.
- Be gentle with fragile hair: less heat, conditioner every wash, soft ties, and a break from extensions, which can pull weak hair out.
- Give it time. Changes happen slowly, so judge progress over months, not days.
Can levothyroxine cause hair loss?
Some people notice extra shedding in the first few months of taking levothyroxine, or after a dose change. It’s usually temporary and settles as levels stabilise. Never stop or change your thyroid medicine without speaking to your GP first.
When it isn’t the thyroid
Having a thyroid condition doesn’t mean it’s causing your hair loss. If your thyroid is well controlled and you’re still losing hair, something else is often involved:
- Female pattern hair loss, which often becomes noticeable at the same stage of life
- Telogen effluvium, from illness, stress or low iron
- Alopecia areata, which is more common in people with autoimmune thyroid disease
- Frontal fibrosing alopecia, if the hairline and eyebrows are receding
I often see people who have been told their hair loss is “just the thyroid” when there is another cause that can be treated.
How I can help
At a consultation in Forest Row I examine your hair and scalp closely, look at the pattern of thinning and take a full history, including your thyroid results, medication, periods, diet and family history.
You leave knowing whether your thyroid explains your hair loss, what else may be involved, and a written plan. If tests or a medication review would help, I’ll write to your GP. What happens at a consultation.
When to see your GP first
Please see your GP or call NHS 111 if:
- your hair loss came on suddenly and you feel unwell
- your scalp is very painful, swollen, weeping or bleeding
- you have patches of hair loss with redness or scarring that are spreading quickly
- you think a new medicine may be the cause. Don’t stop it without speaking to your doctor
You can still see me as well. I’ll happily liaise with your GP if further tests are needed.
Questions about thyroid hair loss
If yours isn’t here, send me a message and I’ll get back to you.
Does an underactive thyroid cause hair loss?
It can. An underactive thyroid can cause thinning all over the scalp and dry, brittle hair. It usually improves once your levels are treated.
Can an overactive thyroid cause hair loss?
Yes. An overactive thyroid can also cause shedding, with hair that becomes fine and soft. Treatment usually brings it back to normal.
How long does it take for hair to grow back after thyroid treatment?
Shedding usually settles within three to six months of your levels becoming stable. Visible regrowth takes longer, often a year or more for long hair.
Does Hashimoto’s cause hair loss?
Hashimoto’s is the most common cause of an underactive thyroid, so it can. People with Hashimoto’s are also more likely to have alopecia areata.
Can thyroid problems cause eyebrow loss?
They can, sometimes at the outer ends of the eyebrows. Eyebrow loss has other causes too, so it’s worth having it checked.
My thyroid is treated but I’m still losing hair. Why?
There may be another cause, such as low iron, female pattern hair loss or shedding from another trigger. It’s worth a full assessment.
Let’s find out what’s going on
Book online at a time that suits you. If you have a question first, send me a message.