Are there any side effects of taking vitamin A capsules?

October 9, 2025 •

2 min read

According to the National Institutes of Health, vitamin A toxicity, also known as hypervitaminosis A, is most commonly linked to excessive supplement intake rather than dietary sources. While essential for vision, immune function, and reproductive health, consuming high doses of vitamin A capsules can have significant and serious side effects.

Quick Summary

Taking excessive vitamin A capsules can lead to toxicity (hypervitaminosis A), causing symptoms that range from dry skin and headaches to severe liver damage and birth defects if taken during pregnancy. Risks are higher with long-term use of high doses of preformed vitamin A from supplements, unlike the safer provitamin A from plant-based foods.

Key Points

Hypervitaminosis A (Toxicity): Excessive intake of preformed vitamin A from capsules can lead to a toxic condition called hypervitaminosis A because it is stored in the liver.
Acute vs. Chronic Effects: Side effects vary based on the dose and duration. Acute toxicity from a single, very high dose can cause nausea, headache, and peeling skin, while chronic toxicity from long-term high doses can lead to liver damage, bone pain, and hair loss.
Preformed vs. Provitamin A: The high risk of toxicity comes from preformed vitamin A (retinol), found in supplements and animal products. Provitamin A carotenoids from plant-based foods (like beta-carotene) are not toxic because the body regulates their conversion.
Serious Long-Term Risks: Chronic overuse can result in severe health issues, including irreversible liver damage, increased risk of osteoporosis, and dangerous pressure on the brain (idiopathic intracranial hypertension).
Risk for Pregnant Women: High-dose vitamin A during pregnancy is teratogenic and can cause severe birth defects. Supplementation should be carefully managed under medical supervision.
Prevention: The safest way to get vitamin A is through a balanced diet. If supplements are necessary, they should be taken within recommended daily allowances and with a healthcare professional's guidance to avoid excess.

The Dangers of Excessive Vitamin A Supplementation

Vitamin A is a fat-soluble vitamin crucial for numerous bodily functions. Because the body stores excess amounts primarily in the liver, there's a risk of accumulation and toxicity over time. Hypervitaminosis A is a known side effect of taking vitamin A capsules in high doses. It's important to distinguish between preformed vitamin A (retinol) in animal products and supplements, which has a high toxicity risk, and provitamin A carotenoids (like beta-carotene) in plants, which pose little risk as the body regulates their conversion.

Acute vs. Chronic Vitamin A Toxicity

Side effects vary based on the dosage and duration of intake.

Acute Toxicity

Acute toxicity occurs from a very large single dose.

Symptoms can appear quickly and may include:
- Nausea and vomiting
- Severe headache
- Skin peeling

Chronic Toxicity

Chronic toxicity results from long-term, daily doses exceeding the Tolerable Upper Intake Level (UL). The adult UL for preformed vitamin A is 3,000 mcg (10,000 IU) per day.

Symptoms are gradual and can include:
- Dry skin and hair loss
- Bone and joint pain
- Enlarged liver and spleen
- Liver damage

Potential Long-Term Complications

Chronic hypervitaminosis A can lead to serious health issues.

Liver Damage: Excess vitamin A can cause liver fibrosis and cirrhosis.
Osteoporosis: High intake may reduce bone density and increase fracture risk.
Teratogenic Effects (Birth Defects): High doses in early pregnancy can cause severe congenital malformations.
Increased Intracranial Pressure: Can cause dangerous pressure around the brain, leading to headaches and vision changes.

Comparison of Preformed Vitamin A vs. Provitamin A

Understanding the difference helps clarify safety.


Feature	Preformed Vitamin A (Supplements, Animal Products)	Provitamin A (Plant Sources like Beta-Carotene)
Toxicity Risk	High risk with excessive intake.	Very low risk; body regulates conversion.
Conversion Rate	Absorbed directly; efficient.	Tightly regulated and slower conversion.
Appearance	No effect on skin color.	Excessive intake can cause a harmless yellow-orange skin tint (carotenosis).
Best Source	Liver, fish oil.	Carrots, sweet potatoes.

Safe Practices for Vitamin A Intake

Meeting vitamin A needs through a balanced diet is safest. Supplements should be used cautiously under medical supervision. Always check the total vitamin A content in all supplements. Individuals with certain medical conditions or those who are pregnant need special attention regarding supplementation and should consult a healthcare provider.

Conclusion

Are there any side effects of taking vitamin A capsules? Yes, especially with high doses. The body stores excess preformed vitamin A, leading to hypervitaminosis A. Side effects range from mild skin changes to severe liver damage and birth defects. A balanced diet is the best way to get vitamin A. Consult a healthcare professional before taking high-dose supplements. If toxicity is suspected, stop the supplement and seek medical advice.

Frequently Asked Questions

The initial signs of excessive vitamin A intake, particularly in cases of chronic toxicity, often include dry, rough, or peeling skin; hair loss; cracked lips; and fatigue. Headaches and irritability may also occur.

Yes, prolonged and excessive intake of preformed vitamin A from capsules can lead to hepatotoxicity (liver damage), which in severe cases can progress to cirrhosis.

Children are more sensitive to vitamin A and can experience toxicity at lower doses than adults. In infants, high doses can cause bulging fontanelles (the soft spot on the head), while older children may experience bone pain and slower growth.

No, it is highly unlikely for beta-carotene from vegetables to cause vitamin A toxicity. The body regulates the conversion of beta-carotene to active vitamin A, and excess intake of carotenoids only causes a harmless yellow-orange tint to the skin, called carotenosis.

In most cases, symptoms of vitamin A toxicity will gradually reverse once the supplement intake is stopped. Mild symptoms may disappear within weeks, but recovery from severe complications like liver damage or bone abnormalities can take longer, and some effects may be permanent.

If you suspect vitamin A toxicity, you should stop taking the supplement immediately and contact a healthcare professional. A doctor can evaluate your symptoms and order blood tests to check your vitamin A levels and liver function.

It is rare to get vitamin A toxicity from diet alone in well-nourished individuals. However, regularly consuming very large amounts of preformed vitamin A-rich foods, such as animal liver more than once a week, especially combined with supplements, can lead to excessive intake.