Do Vitamin D Supplements Help Hair Loss? Only If You Are Low

Vitamin D supplements can help your hair only if you are short of vitamin D, and even then the benefit is modest. If your level is normal, extra vitamin D is very unlikely to regrow hair. It does not treat pattern baldness.

Why the idea took off#

Hair follicles contain vitamin D receptors, which let them respond to the vitamin. In mice, removing those receptors disrupts the hair cycle and causes hair loss. That finding gets quoted a lot, but it does not prove that low vitamin D causes hair loss in people.

Human studies are more mixed. A 2024 systematic review found lower vitamin D levels in some types of hair loss, particularly alopecia areata (patchy autoimmune loss) and telogen effluvium (diffuse shedding after a trigger). The catch is that these studies only show a link. Illness, stress and spending less time outdoors can lower vitamin D and trigger shedding at the same time. Trials of supplements for hair are small and inconsistent.

Pattern hair loss is a different story#

Male and female pattern hair loss are driven mainly by genes and hormones, not by vitamin D. No good evidence shows that supplements slow or reverse them. Treatments with trial evidence include minoxidil for both sexes, and finasteride for men. Our guide to hair masks, vitamins and scalp conditions covers where supplements fit.

Check your level before you buy#

The NHS does not usually test vitamin D just because your hair is thinning. A GP is more likely to test if you have risk factors or symptoms such as bone pain or muscle weakness. Private blood tests (25-hydroxyvitamin D) are available in the UK and usually cost a few tens of pounds. A lab-processed sample is generally more reliable than some home kits.

UK results are in nmol/L. US sources use ng/mL, which is a different unit.

• Below 25 nmol/L: deficient
• 25 to 50 nmol/L: low for some people
• Above 50 nmol/L: adequate for most people

If you are testing, ask about ferritin (iron stores), thyroid function and B12 too. These are more common and more treatable causes of diffuse shedding.

How much to take#

NHS advice is 10 micrograms (400 IU) a day. Everyone should consider this from October to March, when UK sunlight is too weak for your skin to make vitamin D. Some people need it all year. That includes people with darker skin, those who cover most of their skin, older adults, and people who are indoors most of the time. Pregnant and breastfeeding women may qualify for free Healthy Start vitamins.

The safe upper limit for adults is 100 micrograms (4,000 IU) a day. Confirmed deficiency is different. Clinicians use short courses of higher doses, then drop to a maintenance dose. Do not self-prescribe that.

Vitamin D3 usually raises levels better than D2. Vegan D3 made from lichen is available. Take it with a meal that contains some fat. Choose a product from a UK pharmacy or retailer with UK labelling.

Taking too much#

Too much vitamin D can raise calcium in your blood. Warning signs include nausea, constipation, extreme thirst, passing lots of urine and confusion. Over time it can harm your kidneys. Talk to a pharmacist or GP first if you take a thiazide diuretic, or if you have sarcoidosis, kidney stones or high calcium.

How long before you see a difference#

Hair grows in cycles, so changes show up slowly. Shedding from a trigger such as illness, childbirth, a crash diet or menopause often starts 2 to 3 months later. It can settle over a further 3 to 6 months once the trigger passes. Our hair growth cycle guide explains why.

So give any correction of low vitamin D at least 3 to 6 months. Take a photo of your parting each month in the same light. If you were treated for deficiency, your clinician will decide whether and when to retest.

See your GP sooner if hair loss is sudden or patchy, your scalp is sore, red or scarred, or shedding is heavy and has not eased after a few months.