Locations:
Search IconSearch
April 20, 2023/Diet, Food & Fitness

Vitamin A Toxicity: How Much Vitamin A Is Too Much?

Vitamin A toxicity can cause drug interactions, fetal development issues and other side effects

Person with blue shirt is holding vitamin bottle and other hand is holding one vitamin.

Vitamin A is important for visual health. It also contributes to healthy skin and hair and boosts your immunity. If you’re not getting enough, you can develop symptoms like night blindness, dry, scaly skin around your eyes, coarse hair and respiratory infections.

Advertisement

Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy

Vitamin A deficiencies are more common in some parts of the world than others. This is because of many factors, including food insecurity, frequent gastrointestinal infections caused by poor water sanitation, inadequate healthcare access and a high prevalence of measles, which can cause vitamin A to be lost in urine.

While it’s important to avoid a vitamin A deficiency, it’s equally important to make sure you aren’t overdoing it on supplements. We’ll walk you through how much vitamin A you need to feel your best — and what happens when you take too much.

What is vitamin A?

It’s best to get vitamin A from fruits and vegetables that contain carotenoids. In addition to orange-colored vegetables and fruit — carrots, sweet potatoes, squash and papayas — you also need lycopene, astaxanthin, zeaxanthin and lutein. You can find these carotenoids in red and yellow-orange fruits and vegetables, as well as leafy greens, eggs, shrimp and salmon. And don’t forget watermelon, guava, pink grapefruit and tomatoes!

It’s important to get as many vitamins and nutrients as you can from your food. “However, widespread changes in farming practices mean a lower nutrient content in our fruits and vegetables,” cautions functional medicine specialist Melissa Young, MD. “Many people still benefit from having their nutrient levels assessed and taking a high-quality daily multivitamin.”

While a supplement may be the right choice, dosing matters. That’s because there is such a thing as too much vitamin A.

Too much vitamin A symptoms

Fat-soluble vitamins like vitamin A can lead to toxicity because your body doesn’t excrete any excess — it stores it. Vitamin A’s presence in so many different supplements compounds the problem.

Vitamin A doses are measured in micrograms of retinol activity equivalents (mcg RAE). This measurement is to account for the different properties of retinol and provitamin A carotenoids. Depending on your age, sex and whether or not you’re pregnant or lactating, your recommended daily amount is between 500 mcg REA and 1,800 mcg of vitamin A per day REA.

The recommended daily allowance (RDA) for adult men and people assigned male at birth (AMAB) is 900 MCG REA, or 3,000 international units (IU). For adult women and people assigned female at birth (AFAB) the RDA is 700 mcg RAE, or 2,330 (IU). For all adults, the Tolerable Upper Intake Level (UL) — the most vitamin A one can take without experiencing negative health effects — is 3,000 mcg RAE, or 10,000 IU.

“Patients who take a variety of supplements are getting much more vitamin A than they should,” says Dr. Young. Some supplements may include two forms of vitamin A — retinyl acetate and mixed carotenoids — which she says is a good combination for most people. The exception: People who smoke. That’s because clinical trials show that beta-carotene supplements were associated with an increased risk of lung cancer in people who smoke. Smokers or former smokers should not take beta-carotene supplements.

There are two different kinds of vitamin A toxicity: acute and chronic.

Acute vitamin A toxicity symptoms

Acute vitamin A toxicity happens when somebody — usually a child — accidentally ingests a megadose of vitamin A. Common symptoms include:

  • Headache.
  • Rash, which may cause the affected skin to peel later.
  • Drowsiness.
  • Irritability.
  • Stomach pain, nausea and vomiting.

Advertisement

In acute vitamin A toxicity cases, symptoms should resolve over time. Still, if an individual (especially a child) is experiencing these symptoms, you should call Poison Control, and, if directed, go to the nearest emergency room.

Chronic vitamin A toxicity symptoms

Chronic vitamin A toxicity happens when a person takes excessive doses of vitamin A (10,000 IU or more) per day over a prolonged period. The symptoms are more subtle and harder to distinguish from other conditions. They include:

  • Severe headaches and pressure in your skull (idiopathic intracranial hypertension).
  • Hair issues like sparse, coarse hair and alopecia of your eyebrows.
  • Skin issues, like dry, rough, itchy skin (pruritus) and cracked lips.
  • Weakness and susceptibility to fractures.
  • Enlarged liver (hepatomegaly) or spleen (splenomegaly).
  • Children may experience loss of appetite (anorexia), joint pain (arthralgia) and excessive bone growth (cortical hyperostosis). Vitamin A toxicity can also cause “failure to thrive,” which — while not a good thing — sounds scarier than it is. It basically means your child’s growth has either slowed or stopped.

Advertisement

Once you stop taking the supplement, the symptoms of chronic vitamin A toxicity usually take between one and four weeks to resolve.

There’s one very important exception to that rule: Vitamin A is teratogenic, which means it can cause fetal development issues. Once those malformations occur, they can’t be reversed. For that reason, pregnant people — and people who may become pregnant — shouldn’t take excessive doses of vitamin A.

What to do if you’ve taken too much

If you suspect somebody has acute vitamin A toxicity — meaning they ingested a megadose of vitamin A — you should call Poison Control at 1.800.222.1222 for immediate assistance.

If you’re concerned that you or a loved one may be experiencing the effects of chronic vitamin A toxicity, you should schedule an appointment with a healthcare provider. They’ll review your medication and supplements, as well as conduct blood tests, to determine what’s causing your symptoms.

Takeaway

Avoiding vitamin A deficiency is important … but it’s also important to avoid vitamin A toxicity. So, before you pick up those pills or gummies, speak with a doctor. They can let you know if you really need to be taking a supplement — and determine the right dose for your particular situation.

Advertisement

Learn more about our editorial process.

Health Library
Vitamin A Capsules or Tablets

Related Articles

Person talking with doctor on a virtual call about vitamins
May 13, 2024/Nutrition
Yes, You Can Take Too Many Vitamins

If you’re taking supplements, it’s important to understand which vitamins and minerals you can get too much of, like vitamin C and calcium

Person prepping different foods in kitchen
March 20, 2024/Nutrition
What Vitamins You Should Take Is a Personalized Decision

There are several vitamins and mineral supplements that many people can benefit from — but it’s important to consult with a healthcare provider before you start one

vitamin b12 shot in foreground with vials in background
March 5, 2024/Nutrition
Vitamin B12 Injections: What They Can and Can’t Do

If you have low B12 or a true deficiency, these shots can work wonders

Adult hand uses a dropper to deliver a liquid to newborn by mouth
January 18, 2024/Children's Health
Do Infants Need Vitamin D Drops?

A daily dose of vitamin D can help babies build strong bones, as well as boost their brain development

Thiamine or vitamin B1 and potatoe, olive and orange slice
January 15, 2024/Nutrition
6 Health Benefits of Thiamine (Vitamin B1)

Getting enough thiamine in your diet can protect your heart, brain and nervous system

bowl filled with roasted chicken, avocado, quinoa, pickles and herbs
January 11, 2024/Nutrition
Vitamin B5: An Abundant and Beneficial Part of Your Healthy Diet

Also known as pantothenic acid, vitamin B5 helps your metabolism and is found in a wide range of foods

Assorted foods and oils containting vitamin E
January 9, 2024/Nutrition
Top 5 Benefits of Vitamin E

Easy to get from healthy foods, vitamin E can help protect your eyes, boost your immune system and may lower your risk of cancer

assorted foods containing vitamin B
January 7, 2024/Nutrition
A Close Look at Each of the B Vitamins: Benefits, Food Sources and More

B vitamins do a lot for your body, like activate enzymes that give you energy, create blood cells and prevent DNA damage

Trending Topics

Female and friend jogging outside
How To Increase Your Metabolism for Weight Loss

Focus on your body’s metabolic set point by eating healthy foods, making exercise a part of your routine and reducing stress

stovetop with stainless steel cookware and glassware
5 Ways Forever Chemicals (PFAS) May Affect Your Health

PFAS chemicals may make life easier — but they aren’t always so easy on the human body

jar of rice water and brush, with rice scattered around table
Could Rice Water Be the Secret To Healthier Hair?

While there’s little risk in trying this hair care treatment, there isn’t much science to back up the claims

Ad