Quick answer

A dermatology review says consuming too much vitamin A can cause hair loss, citing case reports of people taking vitamin A supplements, one of whom had no more hair loss a month after stopping. NIH's list of effects of too much preformed vitamin A does not name hair loss. It does name dry skin, fatigue and abnormal liver tests.^1,2

Key facts

A dermatology review states that over-supplementing vitamin A can cause hair loss, and cites case reports.¹
In one 1979 case, a woman taking 5,000 IU of vitamin A a day lost hair suddenly, and the loss stopped after one month without the supplement.¹
NIH lists dry skin, painful muscles and joints, fatigue, depression and abnormal liver test results as effects of long-term high vitamin A, and does not list hair loss.²
NIH says severe headache, blurred vision, nausea and dizziness can follow one or a few very large doses of preformed vitamin A.^2,3

What do the sources say about vitamin A and hair loss?

A review of vitamins, minerals and hair loss in the dermatology literature says that consuming too much vitamin A can cause hair loss. It explains that the vitamin is stored in the liver, and when levels get too high, the transport system is exceeded and vitamin A spills over into the blood.¹

It describes two cases. A 28-year-old woman on kidney dialysis noticed sudden hair loss while taking 5,000 IU of vitamin A a day, her blood level was well above normal, and the hair loss was no longer a problem a month after she stopped. A 60-year-old man who took excess vitamin A supplements had hair loss at the front and center of the scalp, less pubic and underarm hair, nail changes and a rash.¹

NIH's fact sheet gives its own list of what long-term high intakes of preformed vitamin A cause, and hair loss is not on it. The sources checked do not explain the difference, and the review is the only one that names hair loss.²

Regular high intakes of preformed vitamin A can cause dry skin, painful muscles and joints, fatigue, depression and abnormal liver test results.²

How much vitamin A is too much for hair?

The sources do not give an amount at which hair loss begins. The review links hair loss to vitamin A toxicity and over-supplementing, and gives a single case at 5,000 IU a day in a person on dialysis, which is below the 10,000 IU (3,000 mcg RAE) NIH names as the adult upper limit for preformed vitamin A.^1,2

The authors of that case concluded that signs of vitamin A excess had been misread as symptoms of the kidney failure, and they highlighted possible harm from vitamin A supplements in people on dialysis.¹

The upper limit for preformed vitamin A is 3,000 mcg a day for adults 19 and older, including in pregnancy and while breastfeeding, and 2,800 mcg for teens 14 to 18. It counts food, drinks and supplements, and it is lower for children: 600 mcg up to age 3, 900 mcg at 4 to 8 and 1,700 mcg at 9 to 13. The limits do not apply to people taking vitamin A under a doctor's care. No upper limit is set for beta-carotene, but the Food and Nutrition Board advises against beta-carotene supplements for the general population except as a source of vitamin A.^2,3

Is hair loss linked to vitamin A medicines too?

The review also describes a study of 30 people treated with isotretinoin, a medicine closely related to vitamin A, for 4 to 7 months, in which hair count, density and the share of growing hairs fell. That is a medicine, not a supplement, and the isotretinoin label tells people to avoid vitamin A supplements.^1,4

Does vitamin A cause headaches, acne, constipation or weight gain?

NIH documents headaches at very large single doses, together with blurred vision, nausea, dizziness, aching muscles and problems with coordination. The sources checked do not address acne, constipation, kidney stones, weight gain, diarrhea or insomnia from vitamin A, which is not a finding either way.^2,3

One or a few very large doses of preformed vitamin A, typically more than 100 times the RDA, can cause severe headache, blurred vision, nausea, dizziness, aching muscles and problems with coordination within days to weeks. In severe cases it can lead to coma and death.^2,3

Who should ask a doctor about hair loss and vitamin A

Anyone with hair loss who takes a vitamin A, fish liver oil or multivitamin product, who should ask their doctor to check the amount of preformed vitamin A and the other causes.^1,2
Anyone taking isotretinoin or another retinoid medicine, who should ask a pharmacist about vitamin A.⁴
Anyone with sudden, patchy or widespread hair loss, since the review discusses other nutrients, such as iron and vitamin D, in hair loss.¹

Questions people ask

Does vitamin A cause hair loss?

A dermatology review says consuming too much vitamin A can cause hair loss, citing case reports. NIH's list of long-term effects of high vitamin A does not name it.^1,2

Does vitamin A cause headaches?

NIH says severe headache can follow one or a few very large doses of preformed vitamin A, typically more than 100 times the RDA, along with blurred vision and nausea. Ask your doctor.^2,3

Does vitamin A cause acne or breakouts?

The sources checked do not address acne from vitamin A, which is not a finding either way. Ask a doctor or pharmacist if skin changes follow a supplement.²

Does vitamin A cause constipation, kidney stones, weight gain or diarrhea?

The sources checked do not address these effects, which is not a finding either way. NIH names dry skin, fatigue and abnormal liver tests among effects of long-term high intakes.²

See what we make

Every product shows its whole label and what its lab report covers. The store opens soon.

See the Full Measure line

Sources

This page is information, not medical advice. Talk to your doctor or pharmacist about your own situation.