What Causes Gray Hair: Causes, Prevention and Treatment Options

Gray hair is caused mainly by ageing: the pigment cells in each hair follicle, called melanocytes, make less melanin over time, so new hairs grow in with little or no colour. Genes set most of the timing, while smoking, stress, vitamin B12 deficiency and thyroid problems can bring it forward.

There is no proven way to stop age-related graying, and this page says so plainly. What you can do is rule out the causes that are treatable, avoid the habits linked to early graying and choose how to manage the gray you have. This guide covers:

• how hair loses its colour, starting in the follicle
• the causes, from genes and age to stress and medical conditions
• what treatment can and cannot do
• the questions people ask most about gray hair at different ages

Look closely at this photo and the "gray" is not one colour. White strands with no pigment grow between strands that still have their dark colour, and together they read as gray from a distance. Each hair's colour is decided in its own follicle, which is why graying spreads hair by hair.

What Is Gray Hair?

Gray hair is hair that grows with little or no melanin, the pigment that colours skin, eyes and hair. Cleveland Clinic explains that the more melanin a hair has, the darker it is, and that gray or white hair comes from having little to no melanin.

The drawing shows that change inside the follicle. As the pigment cells in the hair bulb decline, the hair first grows with less colour and then with none, which is when it looks white.

A head of "gray" hair is usually a mix. A study of photodegradation in gray hair by Richena and colleagues worked with white fibres and black fibres taken from the same gray hair samples. Seen together, white strands mixed with pigmented ones read as gray or silver from a distance.

Gray hair can also feel different. Cleveland Clinic notes that gray strands might be thicker, wirier or coarser. A review of hair structure by Gavazzoni Dias reports that the medulla, the soft central core of a hair, is present in coarser hair such as gray hair, thick hair and beard hair. Our hair shaft anatomy guide explains those layers.

Graying is not limited to the scalp. Cleveland Clinic lists facial hair, body hair, eyelashes and eyebrows as places that also turn gray or white, and notes that facial or body hair can gray long before scalp hair, or the other way round.

What Causes Gray Hair?

Hair gets its colour in the hair bulb, deep in the follicle. A review by Tobin in the International Journal of Trichology explains that bulb melanocytes pass melanin into the growing hair, mainly into its cortex, and that this happens only while the hair is growing. Once the hair leaves the skin, its colour is fixed.

So a gray hair is not a coloured hair that faded. It grew in without pigment, because the melanocytes in that follicle had stopped making enough of it. Our page on the hair bulb shows where these cells sit.

The change is often gradual rather than all or nothing. Tobin describes gray hair bulbs that still show a much reduced, yet detectable, activity of tyrosinase, the key enzyme for making pigment. That fits what many people see: hairs that look paler or silvery before they turn fully white.

The causes found in the sources we reviewed fall into four groups:

Age and Genes

Age is the main driver. Cleveland Clinic says most people start getting gray hairs in their 30s or 40s, but the age and speed vary a lot: some go fully gray within 10 years of their first grays, while others never have a full head of gray hair.

Here almost every hair has lost its colour, with only a few darker strands left. This is the end point of age-related graying that some people reach and others never do, depending largely on their genes.

Genes set much of that timing. In a study of 71 people with early graying by Sonthalia and colleagues, 90.1% had a parent or sibling who had also grayed early. A genetic study of more than 6,000 Latin Americans by Adhikari and colleagues reported the first gene region linked to graying, in the IRF4 gene.

Oxidative Stress

Making pigment produces reactive oxygen species, unstable molecules that can damage cells. Tobin's review notes that oxidative stress may play an important role in graying. A 2009 study by Wood and colleagues in the FASEB Journal found that gray and white scalp hair shafts hold hydrogen peroxide in millimolar concentrations, along with very low levels of the enzymes that normally break it down and repair the damage it does.

Treatment Options

There is no medical treatment that reverses normal graying. A 2025 review in the International Journal of Dermatology states that, to date, no known medical therapies can reverse or prevent premature hair graying. Cleveland Clinic says you cannot stop hair from going gray as you age and probably will not reverse gray you already have.

Treatment therefore works in two ways. The first is finding and treating a medical cause, if there is one. The second is managing how gray hair looks. The 2025 review lists the cosmetic options:

• hair colourants, natural or synthetic
• hair-thickening fibres, made of keratin, that cling to existing hair
• concealing powders and sprays that coat the hair
• wigs and hairpieces, which need frequent care and can be costly

Each option has trade-offs. Dyes need repeat applications as new hair grows in at about 1 cm a month, as explained in our guide to how fast hair grows. Fibres and powders wash out. Hairpieces avoid chemicals on the hair but need upkeep.

Hair dye can cause an allergic skin reaction in some people. The 2025 review notes that the common dye ingredient paraphenylenediamine, known as PPD, gave a positive patch test in 4.5% of patients tested in one study. If your scalp, eyelids, forehead or neck itch or swell after colouring, stop using the product and see a doctor. Newer formulas without PPD exist for people with a known allergy.

What Causes Gray Hair and How to Stop It?

This is the question most people really want answered. The honest version is that you cannot stop the graying that comes with age, but you can sometimes slow or stop graying that has another cause. The steps below follow that logic: rule out what is treatable, cut known risks and then decide how to manage the rest.

Can You Stop Age-Related Graying?

No. Cleveland Clinic states this directly, and the 2025 review found no therapy that prevents or reverses premature graying either. Products that promise to turn gray hair back to its old colour are not supported by the research we reviewed.

There is one piece of genuine new science here, but it is narrow. A 2021 study in eLife by Rosenberg and colleagues mapped colour along single hairs and found white or gray hairs that naturally regained pigment, across sexes, ethnic groups, ages and body regions. Some of these changes ran in parallel with stressful periods in a person's life. The authors propose a threshold model in which hairs near the point of turning gray can tip back for a time. That does not show that long-standing gray hair can be brought back to colour.

Causes You Can Check With a Doctor

Some causes of graying can be found and treated. Cleveland Clinic says that if a vitamin deficiency or other condition is behind the graying, treating it may stop or slow it. The conditions linked to graying in the sources we reviewed include:

• Vitamin B12 deficiency: Kumar and colleagues report that about 55% of people with pernicious anaemia, a cause of B12 deficiency, grayed before 50, compared with 30% of controls.
• Thyroid disease: low thyroid hormone levels are linked to early graying, hair loss and changes in hair texture.
• Vitiligo: a skin condition in which pigment cells are lost, which can also affect hair (vitiligo and hair).
• Alopecia areata: an immune condition that causes patchy hair loss and is listed by Cleveland Clinic among the conditions that affect hair pigment.
• Low copper, iron or other minerals: Kumar and colleagues describe studies that found lower copper, ferritin, calcium and vitamin D levels in some people with early graying.
• Certain medicines: Cleveland Clinic lists some cancer treatments, oral retinoids, antimalarial drugs and epilepsy drugs.

Early graying with no family history is the main reason to ask for tests. A review in the International Journal of Trichology notes that some authors suggest checking vitamin B12, folic acid and thyroid levels in people who gray early without a family history. Only a doctor can decide which tests fit you.

Does Stress Turn Hair Gray?

Stress can play a part, though not overnight. Cleveland Clinic explains that stress can trigger changes in the pigment-producing cells, but because hair gets its colour before it grows out, you would see gray hairs grow in after a stressful period, not appear suddenly.

The strongest lab evidence comes from mice. A 2020 study in Nature by Zhang and colleagues found that acute stress in mice activated the sympathetic nerves around the hair follicle. Those nerves released noradrenaline, which caused the melanocyte stem cells to be used up quickly, and once those stem cells were gone, new hairs grew in white. That work has not been repeated in people in the same way.

In humans, the 2021 eLife study is the closest evidence: graying along single hairs sometimes matched stressful periods, and some hairs regained colour later. Cleveland Clinic notes that when stress levels come down, hairs that went gray could grow back in their original colour.

Smoking and Oxidative Stress

Smoking is one of the clearest lifestyle links. Kumar and colleagues report a significant correlation between smoking and premature graying in studies they reviewed. The likely reason is oxidative stress: the 2025 review notes that smoking produces a large quantity of reactive oxygen species, which can damage hair bulb melanocytes.

The link is a correlation, so it does not prove that stopping smoking will bring colour back. It does make smoking the one well-documented habit linked to earlier graying that a person can change.

Diet, Vitamins and Supplements

A balanced diet supports the body in general, and correcting a real deficiency is a medical step a doctor can take. The research does not support taking supplements to prevent or reverse graying in people who are not deficient. Kumar and colleagues note that vitamins and minerals such as biotin, zinc, copper and selenium are being prescribed for early graying, but that the results have not been promising.

If you are thinking about supplements for your hair, a blood test first is more useful than guessing. Our guide to vitamins for hair loss covers what the evidence says about each one.

Covering Gray Hair With Less Damage

For most people, managing gray hair means colouring it. The American Academy of Dermatology gives practical tips:

• stay within three shades of your natural colour, because going lighter needs stronger chemicals and causes more damage
• have only one chemical service at a time, such as colour, perm or relaxer
• leave more time between touch-ups, especially in dry weather
• use conditioner after every shampoo

Gray hair has its own quirk. Because white hair has no melanin, light and heat affect it more visibly. The study by Richena and colleagues found that a heat treatment at 81°C made white hair turn more yellow, while visible and infrared light bleached it. Heavy use of hot tools may be one reason gray hair can take on a yellow cast.

Graying and Hair Loss Are Different Problems

Graying and thinning often arrive at similar ages, but they come from different parts of the follicle. Graying means the melanocytes have stopped colouring the hair. Thinning means the follicle is making a smaller hair, or none at all. Our guide to the reasons for hair loss explains the common causes of thinning.

The two can overlap when a transplant is planned. A 2026 article by Park in Clinical, Cosmetic and Investigational Dermatology explains that gray or white hair lowers the colour contrast between hair and scalp, so the scalp can look more visible even when density is kept. It also notes that white hair is harder to see during surgery, which can raise the risk of damaging grafts, and describes dyeing the hair beforehand as one strategy.

How It Compares

Not every loss of colour is the same. The table below compares the patterns described in the sources we reviewed:

Ethnic background also matters. A worldwide study by Panhard and colleagues of 4,192 people found that 74% of those aged 45 to 65 had some gray hair, with an average gray coverage of 27%. People of Asian and African descent had less gray hair than people of Caucasian origin at the same ages.

The study also tested the old 50/50/50 rule, which says that half of people have at least 50% gray hair by age 50. The real share was 6% to 23%, depending on origin and natural hair colour, well below the rule.

What Makes Your Hair Dry?

Gray hair often feels drier and coarser than pigmented hair, and several things add to that. Cleveland Clinic describes gray strands as possibly thicker, wirier or coarser. Gavazzoni Dias links the medulla to coarser hair, including gray hair.

Hair care adds to the effect. The American Academy of Dermatology notes that colouring and perming can leave hair dry and brittle, which matters because many people with gray hair colour it often. Gavazzoni Dias explains that bleaching, dyeing, rough washing, unprotected drying and sunlight strip the fatty outer layer that helps hair repel water, leaving the surface rougher.

Frequently Asked Questions

Gray Hair and Thinning at the Same Time?

Gray hair needs no treatment on medical grounds, but thinning can be assessed. If you are going gray and thinning at once, a photo review can show where density has dropped. Send:

• the front hairline, hair pushed back
• the top of the head, from above
• the back and sides, where donor hair sits

Then ask for a free hair analysis. If a transplant is suitable, our hair transplant cost page lists the all-inclusive packages from $2,550 to $4,500.

Medical disclaimer: This article is for informational purposes only and is not medical advice. Individual results and recovery vary from person to person. Always follow the written aftercare plan from your own medical team.