What are the symptoms caused by vitamin A? Understanding Deficiency and Toxicity

January 4, 2026 •

4 min read

According to the World Health Organization, vitamin A deficiency is the leading cause of preventable blindness in children globally. Understanding the full spectrum of symptoms caused by vitamin A imbalance is crucial, as both too little and too much can lead to serious health consequences affecting vision, skin, and overall well-being.

Quick Summary

A vitamin A imbalance, from deficiency to toxicity, can manifest in a range of symptoms. Lack of vitamin A often affects vision, leading to night blindness and dry eyes, while an excess can cause headaches, liver damage, and skin abnormalities like dryness and peeling.

Key Points

Night Blindness is a First Sign: An early symptom of a vitamin A deficiency is difficulty seeing in low light conditions.
Vision Problems Range Widely: A deficiency can progress from night blindness to severe dry eyes and, if untreated, irreversible blindness.
Toxicity Can Harm the Liver: Chronic excess vitamin A intake can cause liver damage, including enlargement (hepatomegaly) and potentially lead to cirrhosis.
Skin Issues Are a Common Indicator: Both low and high levels of vitamin A can cause skin problems, including dryness, flaking, cracking, and rashes.
Excess is Often Caused by Supplements: Acute or chronic vitamin A toxicity typically results from consuming high doses of supplements, not from a balanced diet.
Pregnancy Poses a Unique Risk: Very high vitamin A intake during pregnancy is dangerous and can lead to severe birth defects.

The Dual Nature of Vitamin A

Vitamin A is a fat-soluble nutrient essential for numerous bodily functions, including vision, immune function, reproduction, and cell growth. However, because the body stores this vitamin in the liver, both a prolonged lack of it and an excessive intake can lead to adverse health effects. The symptoms differ dramatically depending on whether the body has too little or too much.

Vitamin A Deficiency Symptoms

Deficiency is uncommon in developed countries but remains a significant public health issue in many developing nations. The most common and severe symptoms relate to vision, but other systems are also affected.

Eye and Vision Problems: The most recognized sign is night blindness (nyctalopia), making it difficult to see in dim light. This is an early warning sign. If the deficiency progresses, it can lead to more severe conditions like xerophthalmia, characterized by dryness of the conjunctiva and cornea. Bitot's spots, foamy patches on the whites of the eyes, may also appear. The most severe outcome is keratomalacia, which is the softening and ulceration of the cornea that can result in irreversible blindness.
Skin and Hair Issues: A lack of vitamin A can cause the skin to become dry, scaly, and rough due to its role in maintaining epithelial tissue integrity. Hair may also become dry and coarse. Itchy skin (pruritus) is another potential symptom.
Immune System Dysfunction: Vitamin A is vital for a healthy immune system, and deficiency can impair the body's ability to fight off infections. This leads to a higher risk and increased severity of common infections, particularly respiratory diseases (like pneumonia) and diarrhea, especially in young children.
Growth and Reproductive Issues: In children, deficiency can cause stunted growth and delayed bone development. In adults, it can contribute to infertility and increase the risk of miscarriage in pregnant women.

Vitamin A Toxicity (Hypervitaminosis A) Symptoms

In contrast to deficiency, toxicity typically occurs from excessive intake, usually from high-dose supplements or certain retinoid medications, not from food alone. It can be either acute (short-term, very high dose) or chronic (prolonged high doses).

Acute Toxicity Symptoms:

Severe headache and blurred vision
Nausea and vomiting
Drowsiness, irritability, and changes in mental status
Peeling skin (desquamation)
Increased pressure within the skull (idiopathic intracranial hypertension)

Chronic Toxicity Symptoms:

Skin and Hair: Dry, rough, and cracked skin, particularly on the lips. Hair loss (alopecia), including eyebrows.
Musculoskeletal: Bone and joint pain, which can be severe. In older adults, it can increase the risk of fractures and osteoporosis. Infants and children might experience bulging fontanelles and painful swelling over bones.
Hepatic Damage: Liver enlargement (hepatomegaly) and elevated liver enzymes are common. Long-term, high intake can lead to liver fibrosis or cirrhosis.
Central Nervous System: Persistent and severe headaches, dizziness, and pseudotumor cerebri (increased intracranial pressure).
Other Symptoms: Fatigue, anorexia (loss of appetite), and yellow-orange skin (carotenosis) from excess carotene intake.

Comparison of Vitamin A Deficiency and Toxicity Symptoms

To help differentiate between the two conditions, here is a comparative overview of common symptoms.


Symptom Area	Deficiency (Hypovitaminosis A)	Toxicity (Hypervitaminosis A)
Vision	Night blindness, dry eyes, potential blindness	Blurred or double vision, headaches, papilledema
Skin	Dry, scaly, rough skin, itching	Dry, cracked skin and lips, peeling skin, rash
Hair	Dry, coarse hair	Hair loss, including eyebrows
Energy & Appetite	Fatigue, poor appetite, poor growth	Fatigue, anorexia, poor weight gain in children
Bone Health	Delayed bone growth in children	Bone and joint pain, osteoporosis risk, fractures
Liver	Not directly affected	Enlargement (hepatomegaly), potentially cirrhosis
Immunity	Weakened immune system, frequent infections	Immune function disturbances
Causes	Inadequate dietary intake, malabsorption issues	Excessive supplement use, certain medications

Potential Complications and Considerations

While symptoms of vitamin A toxicity often reverse upon stopping excess intake, certain complications, particularly from chronic toxicity, may be more persistent. Liver damage and bone abnormalities can lead to long-term health issues. Furthermore, a specific and serious concern is the teratogenic effect of high vitamin A intake during pregnancy, which can cause severe birth defects. Pregnant individuals should strictly adhere to recommended intake levels and avoid high-dose supplements. For more information on dietary needs, the Mayo Clinic provides a comprehensive overview of Vitamin A.

Conclusion

The symptoms associated with an imbalance of vitamin A are wide-ranging and can affect multiple body systems, most notably vision, skin, and bones. Deficiency, though rare in developed countries, leads to impaired sight, dry skin, and a weakened immune system. In contrast, toxicity, often caused by over-supplementation, can result in headaches, bone pain, and serious liver damage. Both states highlight the critical importance of maintaining a balanced intake. Consulting a healthcare professional for a proper diagnosis is essential if you suspect you are experiencing symptoms related to either a deficiency or an excess of vitamin A. Addressing the underlying cause is key to recovery and preventing irreversible damage.

Frequently Asked Questions

The earliest and most common sign of a vitamin A deficiency is night blindness, where you have trouble seeing in dimly lit areas. Other signs include dry eyes and frequent infections.

Eating too many carotenoid-rich foods like carrots will not cause vitamin A toxicity. Excess carotenoids, which the body converts to vitamin A, are stored in fat and can harmlessly turn your skin yellow-orange, a condition called carotenosis.

Yes, headaches are a common symptom of both acute and chronic vitamin A toxicity. In severe cases, they can be a sign of increased intracranial pressure.

A deficiency can cause dry, rough, or scaly skin, while toxicity can lead to dry, cracked lips and skin, rashes, and peeling.

Both deficiency and excess can negatively impact immune function. A deficiency can weaken your ability to fight infections, making you more susceptible to illnesses.

No, pregnant women should avoid high-dose vitamin A supplements. Excessive intake during pregnancy is associated with a risk of severe congenital malformations in the fetus.

The primary treatment for vitamin A toxicity is to stop consuming the source of excess vitamin A, such as high-dose supplements. Symptoms typically improve gradually over weeks or months.