Quick answer

Side effects come mainly from too much preformed vitamin A, the kind in liver and many supplements. Very large doses cause severe headache, blurred vision, nausea and dizziness, and regular high intakes can harm the liver and, in pregnancy, the baby. Adults should stay under 3,000 mcg a day. Beta-carotene can turn skin yellow-orange.^1,2

Key facts

Acute toxicity usually follows one or a few doses of more than 100 times the RDA.¹
The adult limit counts preformed vitamin A from food and drinks as well as from supplements.²
Children's limits are far lower: 600 mcg a day up to age 3 and 900 mcg at 4 to 8.²
Beta-carotene does not cause the toxic effects of preformed vitamin A; in large amounts its main effect is a harmless tint to the skin.^1,2

Signs of too much

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.^1,2

Regular high intakes of preformed vitamin A can cause dry skin, painful muscles and joints, fatigue, depression and abnormal liver test results.¹

Because the body stores the excess in the liver, problems from regular high intakes build up over time. The upper limit for adults was set from the amounts linked to liver abnormalities and to birth defects.¹

Effects on the skin

Large amounts of beta-carotene over a long time can turn the skin yellow-orange. The change is harmless and fades when intake falls.^1,2

Dry skin can be a sign of regular high intakes of preformed vitamin A. The yellow-orange tint from beta-carotene is a different thing: it is harmless and reverses once you take less.^1,2

Pregnancy and prenatal vitamins

Too much preformed vitamin A in pregnancy can cause birth defects, including malformations of the eye, skull, lungs and heart.^1,2

Prenatal supplements generally provide no vitamin A in the form of retinol.³

The usual advice for anyone who is or might be pregnant, or is breastfeeding, is to avoid supplements that give more than 3,000 mcg RAE (10,000 IU) of preformed vitamin A a day. Beta-carotene is not known to cause birth defects.¹

Smokers and beta-carotene

In two large trials, smokers, and in one also people exposed to asbestos, who took 20 to 30 mg of beta-carotene a day had more lung cancer and more deaths. NIH says smokers, and possibly former smokers, should avoid multivitamins with large amounts of beta-carotene or vitamin A.^1,3

In a third trial, of an eye supplement with 15 mg of beta-carotene a day given to people who did not currently smoke, more lung cancers were found in the beta-carotene group (23 against 11), and 31 of the 34 people affected were former smokers. Trials with fewer smokers did not raise this concern.¹

For scale, a multivitamin listing 600 mcg RAE from beta-carotene contains about 1.2 mg of it, because 2 mcg of supplemental beta-carotene counts as 1 mcg RAE. If you smoke or used to, ask your doctor before taking any product with beta-carotene.^1,3

Bones

In pooled observational studies, the highest intakes of vitamin A and of retinol were linked to more hip fractures, while beta-carotene intake was not, and both very low and very high blood retinol were linked to more hip fractures. Studies of this kind cannot show cause.⁴

The link was with hip fractures, not with fractures overall, and it did not apply to beta-carotene. If you have been told you have thin bones, show your doctor the labels of any supplements that contain preformed vitamin A.⁴

Children

Upper limits for preformed vitamin A in children and teens¹
Age	mcg a day
Birth to 12 months	600
1 to 3 years	600
4 to 8 years	900
9 to 13 years	1,700
14 to 18 years	2,800

A single adult supplement with 3,000 mcg of preformed vitamin A is above every one of these limits, so give a child vitamin A only on a doctor's or pharmacist's advice.¹

Medicines

Avoid the combination unless your doctor advises it

The isotretinoin label says to avoid using it with supplements that contain vitamin A, because isotretinoin is closely related to vitamin A and the combination may lead to isotretinoin's adverse reactions. NIH says retinoid medicines taken with vitamin A supplements can raise the risk of vitamin A toxicity, and MedlinePlus lists vitamin A supplements among the products that may interact with isotretinoin.^1,5,6

On the medicine's label

The same concern applies to acitretin and bexarotene, retinoid medicines that NIH says can raise the chance of vitamin A toxicity when combined with vitamin A supplements. Orlistat works the other way, lowering how much vitamin A and beta-carotene you absorb.¹

Questions people ask

Can I take vitamin A every day?

Daily intake is how the recommended amounts are set, and most people get them from food. If you take a supplement daily, keep preformed vitamin A from all sources under 3,000 mcg a day, and ask your doctor first if you are pregnant, smoke or take a retinoid medicine.^1,2

What are the side effects of vitamin A in children?

Children's upper limits are much lower than adults', from 600 mcg a day for babies and toddlers to 1,700 mcg at 9 to 13. Signs of too much include headache, blurred vision, nausea and dizziness.^1,2

Does vitamin A turn your skin yellow?

Beta-carotene can, after large amounts over a long time. The tint is harmless and fades when you take less. Regular high intakes of preformed vitamin A can dry the skin instead.^1,2

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