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RE:YOU

HAIR CARE

By: RE:YOU Editorial Team

How Hormones Influence Hair Growth

Lara Doğan

Reviewed by

Lara Doğan, MS in Biomedical Sciences

Lara is a molecular biologist specializing in the validation of science-backed approaches to treating hair thinning and hair loss.

Learn how estrogen, progesterone, DHT, thyroid hormones, and stress affect hair growth, and what to do during shedding or thinning.

How Hair Grows

Hair grows in cycles. Most hairs are growing, and some are resting.

Hormones control this cycle. When they change fast, like during pregnancy or after having a baby, more hairs go into the resting stage. This doesn't mean your hair is damaged. You'll just see more shedding for a while, often weeks after the hormone change.

Shedding After Pregnancy

Lots of people notice hair changes after having a baby. Estrogen and progesterone rise during this time, keeping more hair in the growing stage. That's why hair often looks thick and full.

After birth, estrogen drops fast, causing extra shedding [2]. Doctors call this telogen effluvium, when a lot of hair rests at once. 

Most people notice shedding around 2 to 4 months after birth [1]. It can feel scary, but it's usually temporary, and hair grows back once hormones settle.

Pregnancy isn't the only cause. Low iron, thyroid problems, and stress can play a part too. See a doctor if shedding is heavy, long-lasting, or comes with an itchy scalp.

Pattern Hair Loss and DHT

Not all hair loss is shedding. Some happen slowly, called pattern hair loss: thinning at the temples, a wider part, or less hair on top.

Hormones called androgens cause this. DHT, one of them, makes hair follicles shrink little by little, so hair grows thinner and shorter over time. Your body makes DHT from testosterone [6], and in some scalps this process speeds up, speeding up thinning too [5].

This builds up slowly, over months or years. Doctors usually treat it with medicine that blocks DHT. Healthy habits help hair, but usually can't fix this kind of loss alone.

Thyroid and Hair

Your thyroid affects hair too. Too much or too little thyroid hormone can throw off hair growth: more shedding, dry hair, or hair that feels different.

Thyroid problems can be hard to catch, so doctors check for them when hair loss is heavy or doesn't stop, especially with tiredness, weight changes, or feeling too hot or cold. Thyroid issues can overlap with other causes too, so doctors often check more than one thing.

Stress and Hair

Most people think of hormones like estrogen. But stress hormones matter too. One study found too much cortisol, a stress hormone, can also cause hair problems [3].

Stress can make things worse. It affects your sleep, eating, and hormones, all of which can slow hair growth.

Take care of your body: eat well, get protein, manage stress, and sleep enough. These habits help your hair grow the way it should.

Watch for these clues:

  • Timing: Shedding started a few months after a big change, like having a baby or starting new birth control.

  • Pattern: All-over shedding usually means telogen effluvium [3]. Thinning at the part or temples usually means pattern hair loss [5].

  • Hair texture: Hair getting thinner and shorter over time points to pattern hair loss.

  • Other symptoms: Feeling tired, weight changes, or irregular periods can point to a thyroid issue.

When To See a Doctor

See a dermatologist if hair loss is bothering you. You don't have to wait until it gets worse.

A dermatologist will ask when shedding started and look at your scalp closely. They may also run blood tests, especially for thyroid or hormone levels [4].

Take photos of your hair every few weeks. This makes it easier to see if things are getting better or worse.

How to take care of your hair

You can't control your hormones alone, but you can be gentle with your hair. Use a wide-tooth comb, avoid brushing wet hair hard, skip tight hairstyles, and use less heat with heat protection.

Take care of your scalp too: use a gentle shampoo, and treat dandruff or itching directly.

Look for products that reduce breakage. If you have pattern hair loss, ask your dermatologist about treatment, since products alone won't fix it.

Shedding from hormones often improves in a few months. Pattern hair loss takes longer. Eating well, getting enough iron, and sleeping well all support healthy hair.

The Bottom Line

Hormones control how your hair grows and sheds. Falling estrogen causes shedding after pregnancy [2][4]. DHT causes pattern hair loss [5][6]. Pay attention to timing and patterns, and see a dermatologist if shedding is heavy or doesn't stop. Once you know the cause, you can take the right steps to help your hair grow back.

References

  1. Postpartum Hair Loss — Johns Hopkins Medicine (https://www.hopkinsmedicine.org/health/wellness-and-prevention/postpartum-hair-loss)

  2. Postpartum Hair Loss: Causes, Treatment & What to Expect — Cleveland Clinic (https://my.clevelandclinic.org/health/diseases/23297-postpartum-hair-loss)

  3. Hair loss in new moms: Dermatologist tips — American Academy of Dermatology (AAD) (https://www.aad.org/public/diseases/hair-loss/insider/new-moms)

  4. Hormonal Effects on Hair Follicles — PMC (https://pmc.ncbi.nlm.nih.gov/articles/PMC7432488/)

  5. Androgenetic Alopecia — StatPearls, NCBI Bookshelf (https://www.ncbi.nlm.nih.gov/books/NBK430924/)

  6. Definition of dihydrotestosterone (DHT) — NCI Drug Dictionary (https://www.cancer.gov/publications/dictionaries/cancer-drug/def/dihydrotestosterone)