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Why does hair turn grey?

Medicine & HealthLesson on requestFree to readयह पेज हिंदी में पढ़ें

Quick answer

Grey hair appears when melanocytes, the pigment cells inside hair follicles, gradually stop producing melanin. As we age, the stem cells that replenish melanocytes decline, so new hair grows without pigment. Genetics largely determine when this starts, though stress, nutrition and some medical conditions can influence the timing.

Hair turns grey when the pigment-producing cells in each follicle gradually stop making melanin, so new hair grows without colour. This happens mainly because those melanocyte stem cells decline with age, though genetics and some health factors can speed it up.

Step by step

  1. Each hair follicle contains a small reservoir of melanocyte stem cells in a region called the bulge.
  2. These stem cells normally divide to replace melanocytes, which make melanin pigment.
  3. With age, the stem cells divide less often and eventually stop producing new melanocytes.
  4. The follicle continues to build hair, but without melanin the shaft is transparent or white.
  5. The hair appears grey because it mixes with still-pigmented hairs nearby, then turns fully white.

Key things to understand

  1. Each hair follicle contains melanocytes, cells that inject the pigment melanin into the growing hair shaft.
  2. Melanin comes in two forms, eumelanin for dark brown or black and pheomelanin for red or yellow tones.
  3. Over time, the melanocyte stem cells in the bulge region of the follicle divide less and eventually stop producing new melanocytes.
  4. Without fresh melanocytes, the hair shaft is built with no pigment, so it appears grey, silver or white.
  5. Grey hair often feels coarser because the follicle also changes size and oil production with age.

Labelled diagram

  1. Follicle base

    The follicle's bulge holds melanocyte stem cells that resupply pigment-making cells at the base.

  2. Melanocytes

    Produce melanin and inject it into the growing hair shaft.

  3. Stem cell decline

    With age, stem cells divide less and stop replacing melanocytes.

  4. Pigment-free hair

    New hair grows without melanin, so it looks grey or white.

How a hair follicle loses pigment

Real-world examples

  • A person in their fifties may notice a few silver strands at the temples before greying spreads across the whole head.
  • Some people notice grey hairs in their twenties, usually because of an inherited pattern rather than lifestyle.
  • In vitiligo, an autoimmune condition, melanocytes are attacked, causing white patches on skin and sometimes white hair.
  • Certain chemotherapy drugs can damage melanocytes and cause temporary or permanent greying in some patients.

Common mistake

✗ Myth: Grey hair is caused by stress alone.

✓ Fact: Genetics is the main driver of when you go grey. Stress and health issues can influence timing, but they do not override your inherited pattern.

People also ask

What causes grey hair?
Grey hair is caused by a gradual loss of melanocytes, the pigment-producing cells in hair follicles. As these cells decline with age, new hair grows without melanin. Genetics determines the timing, while stress, nutrition and certain medical conditions can affect how quickly it happens.
Why does hair turn white not grey?
Hair is actually white when it has no pigment. A head looks grey when white hairs mix with pigmented ones, and single hairs that keep a little melanin also look grey. As more hairs lose pigment, the overall appearance shifts from grey to white.
Can grey hair turn black again?
Once a follicle stops producing melanin, that hair usually stays grey or white. In rare cases where greying is linked to a treatable condition like a nutrient deficiency or thyroid problem, colour may return after treatment. Otherwise, the change is permanent.
Can stress make your hair turn grey?
Stress can speed up greying in some people, but it is not the main cause. The effect is usually gradual and linked to how stress hormones affect melanocyte stem cells over years, not overnight.
Is grey hair reversible?
Once a follicle stops making melanin, that hair usually stays grey. Some temporary greying linked to nutrient deficiencies or thyroid problems can reverse if the underlying cause is treated, so see a doctor if it happens suddenly.
Why do some people go grey in their twenties?
Early greying is mostly genetic. If your parents or grandparents went grey young, you are more likely to as well. Certain medical conditions and nutrient deficiencies can also contribute.
Does plucking a grey hair cause more to grow?
No. Plucking removes one hair, but the follicle will grow a new one. That new hair will still be grey because the pigment cells in that follicle are already depleted.

Part of the guide: How Your Body Works →