Grey hair: why it happens early and can it be reversed?

Hair turns grey (also spelled gray) when the pigment cells at the root slow down and stop making color. For most people this is set by genes and age. A few causes of early greying are worth checking with a doctor, and some stress-related greying may partly reverse, but no pill or serum has been shown to bring color back.

Quick answer: Most grey hair is genetic and permanent. If you go grey very early, ask a doctor whether checking vitamin B12, thyroid function and other blood tests makes sense. Not smoking may help delay greying. Research suggests some recently greyed hairs can regain color, possibly when stress eases. Otherwise, color it, gloss it, or embrace it with grey-friendly care.

Why hair turns grey

Hair color comes from melanin, a pigment made by cells called melanocytes at the base of each hair follicle. These cells are topped up from a small reserve of pigment stem cells.

With age, that reserve shrinks and the remaining cells make less pigment. New hairs grow in with less color (grey) or none (white). The American Academy of Dermatology (AAD) notes that, on average, hair starts to grey in the 30s to 40s. Researchers also think oxidative stress, a build-up of reactive molecules that damage cells, plays a part.

Grey hair is not dyed hair losing color. Each hair grows in grey from the root, which is why greying happens strand by strand.

When is greying "premature"?

Doctors usually call greying premature if it starts:

• Before about age 20 in white people
• Before about age 30 in Black people
• Around age 25 has been suggested for people from the Indian subcontinent, though this cutoff is less established

The strongest factor is family history. If your parents went grey early, you may too.

Causes worth checking

Most early greying has no medical cause, but reviews of the research link it with:

• Vitamin B12 deficiency. Several studies found lower B12 levels in people with premature greying, though not all studies agree. Low vitamin D, iron and copper have also been reported.
• Thyroid problems. Thyroid hormones affect hair follicles, and an underactive thyroid has been linked to early greying.
• Smoking. One of the most consistent links. Smoking was more common in people with premature greying in several studies, possibly because it adds oxidative stress.
• Autoimmune conditions. Vitiligo can cause white patches of hair, and in alopecia areata (patchy hair loss), hair often regrows white at first.
• Stress. The AAD notes stress can speed up greying.

Most of this evidence comes from observational studies, which show links but cannot prove cause.

Does stress cause grey hair?

In a 2020 study in mice, researchers found that sudden, intense stress overactivated nerves near the hair follicle and used up the pigment stem cells, turning fur grey for good. The NIH summarized it as a possible explanation for stress greying, but it was done in mice.

In people, a study that mapped color along single hairs found that some grey or white hairs naturally regained color. In a few cases this lined up with periods of lower stress. The researchers suggest this is most likely in hairs close to the "tipping point" of turning grey, not in hair that has been grey for years.

So stress may speed greying, and some recent greying may partly reverse. Long-standing grey from age and genes is very unlikely to come back.

Can grey hair be reversed?

Only in limited cases:

• Treating a real B12 deficiency or thyroid problem may slow greying, and in some reports hair color partly returned.
• Some recently greyed hairs may regain color on their own.
• Supplements, "anti-grey" serums and special diets have not been shown to restore color in genetically grey hair. The AAD says there are no effective medical treatments to restore color.

Plucking does not help. The AAD warns that plucking can thin your hair, and the hair grows back grey anyway.

Coloring options for grey hair

Patch test every time. Many permanent dyes contain para-phenylenediamine (PPD), a common cause of allergic reactions. The NHS advises a skin test at least 48 hours before each use, and avoiding PPD dyes if you have ever reacted to hair dye or a "black henna" tattoo. A negative test does not fully rule out a reaction later. More on dyed hair at color-treated hair and colorants.

Henna and chemical dye. Some products sold as henna contain added dyes or metal salts that react badly with bleach or permanent dye. Do a strand test and tell your stylist.

Caring for grey hair

• Purple or silver shampoo once a week can tone down yellowing.
• More moisture. Grey hair often feels coarser and drier, so use a rich conditioner and a weekly mask. See dry and damaged hair.
• Heat protection. High heat can make light hair look yellow, so use a heat protectant and lower settings.
• Sun protection. A hat helps protect both your scalp and hair from UV light.

What not to do

• Dye without a patch test. Allergic reactions to hair dye can be severe.
• Mix henna with bleach or chemical dye without a strand test.
• Pluck grey hairs. It can damage follicles and thin your hair.

How long until you see results

Hair dye works right away. If a deficiency or thyroid problem is treated, any change in new growth takes months, because hair grows slowly and only new hair can show it.

When to see a doctor

See a doctor or dermatologist if you notice:

• Greying in your teens or early 20s with tiredness, pale skin, numbness or tingling (possible B12 deficiency)
• Signs of thyroid problems, such as weight changes, feeling cold, or a fast heartbeat
• Sudden white patches of hair, or patches of hair loss (thinning hair)
• White or light patches on your skin (possible vitiligo)
• Burning, swelling or blistering of the scalp, face or eyelids after dyeing (seek urgent care if swelling is severe)

FAQ

Does plucking one grey hair make more grow?

No. It does not cause more greys, but plucking can damage the follicle and thin your hair over time, and the hair still grows back grey.

Can stress turn hair grey overnight?

Not overnight. Hair that has already grown cannot change color. Stress may speed up greying in new hair growth.

Is grey hair weaker?

Not necessarily, but it often feels drier, coarser or wiry, so it benefits from extra conditioning.

Can vitamins reverse grey hair?

Only if you have a real deficiency, and even then results vary. Taking supplements you don't need has not been shown to bring color back.

Sources

• What causes gray hair, and can I stop it? (American Academy of Dermatology)
• Premature graying of hair: review with updates (PubMed Central, NIH)
• How stress causes gray hair (NIH News in Health)
• Quantitative mapping of human hair greying and reversal in relation to life stress (PubMed Central, NIH)
• Hair dye reactions (NHS)