• Vitamins and Supplements
• Nutrition

Understanding Vitamin A Toxicity: Causes, Symptoms, and Prevention

Many people consider taking vitamin A supplements to improve their immune function, vision, and other aspects of their health. 

While this is beneficial, people on vitamin A supplements may start to experience unusual symptoms after a few weeks — such as persistent headaches, nausea, or changes in their skin. 

This could be a sign that your supplement dosage is too high and that you may have developed a condition called vitamin A toxicity. 

Although this condition is highly treatable, it’s important to recognize the symptoms and seek medical guidance as soon as possible to avoid serious complications. 

In this article, we’ll cover everything you need to know about vitamin A toxicity, including common causes, treatments, and prevention strategies to help you manage your health.

What is Vitamin A Toxicity?

Vitamin A is essential for various bodily functions —  including vision, immune function, and cellular growth.

However, since excess vitamin A accumulates in the liver and fatty tissues instead of being excreted, high levels can lead to vitamin A toxicity.

This condition — also known as hypervitaminosis A or vitamin A poisoning — occurs when the body has stored too much of this nutrient.

It can happen due to consuming high amounts of vitamin A over a short time or consistently exceeding the recommended dietary allowance (RDA).

There are two types of vitamin A poisoning:

• Acute vitamin A poisoning: This occurs when you consume too much vitamin A over a short period of time, such as a few hours or days. It can happen when eating large amounts of vitamin A-rich foods or taking dietary supplements with a high dose.

• Chronic vitamin A poisoning: This develops when you consume too much vitamin A over an extended period of time, typically ranging from three months to several years. It usually occurs due to regularly taking large doses of vitamin A supplements.

How much vitamin A is poisonous to humans?

The RDA of vitamin A is 900 micrograms (mcg) for men and 700 mcg for women. Depending on how you obtain your vitamin A, this amount could be consumed through:

• Eating one cup of cooked kale (885 mcg)

• Eating around 10 cups of cubed mango (89 mcg per cup)

• Having one cup of chopped carrots (835 mcg)

These foods are just some of the many options rich in vitamin A and beta-carotene — an unprocessed form of vitamin A — that you can add to your diet.

For supplements, the vitamin A content per pill can vary. Be sure to read to label to avoid exceeding the RDA.

Remember that consuming the RDA of vitamin A is generally considered safe and won’t increase your risk of toxicity.

The tolerable upper intake level — or the maximum amount — for adults is 3,000 mcg of vitamin A per day.

However, this amount isn’t always considered safe, especially because it can significantly increase your risk of developing acute or chronic toxicity if you exceed it. 

The table below details the maximum vitamin A thresholds:

How common is vitamin A poisoning?

In the United States, vitamin A toxicity is relatively rare, as most people have access to medical professionals who can guide their nutrient intake.

However, vitamin A poisoning can still occur due to:

• Over-supplementation: Individuals taking high-dose vitamin A supplements without medical supervision are at higher risk of developing toxicity.

• Dietary excess: Consuming large amounts of liver or other vitamin A-rich foods may lead to toxicity — particularly in cultures with diets high in these products.

• At-risk populations: Children, pregnant women, and individuals with certain health conditions — like liver disease — may be more susceptible to vitamin A toxicity. In pregnant women, vitamin A poisoning can also cause birth defects.

Common Signs of Vitamin A Toxicity

The signs and symptoms of vitamin A toxicity can vary depending on if it’s acute or chronic. Let’s take a look at the different symptoms. 

Acute toxicity 

If you’ve developed acute vitamin A toxicity, you may experience the following:

• Nausea and vomiting, often shortly after ingesting vitamin A 

• Severe headaches

• Dizziness and confusion 

• Blurred vision 

• Muscle pain and weakness

• Feeling uncoordinated 

• Peeling skin on the palms and soles 

• Irritability

• Drowsiness 

With proper treatment, these symptoms typically resolve in a few weeks or months. There are currently no known long-term complications of acute toxicity.

Chronic toxicity 

Chronic toxicity may be more serious and can cause the following symptoms to develop:

• Poor appetite

• Bone pain

• Swollen joints 

• Dry, rough skin

• Signs of liver damage, including jaundice and abdominal pain

• Hair loss

• Persistent headaches and dizziness

• Pseudotumor cerebri, which is when increased pressure in the skull mimics a brain tumor

• Persistent vision issues, including night blindness

• Cracked fingernails

• Sensitivity to sunlight

• Mouth ulcers

• Frequent respiratory infections

Depending on the effectiveness of the treatment, chronic toxicity can resolve within four weeks.

In children 

Children with vitamin A toxicity may experience symptoms such as:

• Softening of the skull 

• Bulging eyeballs

• Double vision 

• Bulging of the soft spot on top of an infant’s skull

• Inability to gain weight 

• Coma 

If you suspect your child has vitamin A poisoning, seek medical attention immediately to avoid serious complications. 

Can You Treat Vitamin A Toxicity?

Immediate steps to reduce vitamin A levels

The first step in treating vitamin A poisoning is to reduce your intake and restore balance in the body.

This can be done by discontinuing the use of vitamin A supplements and avoiding eating foods high in this nutrient. 

It’s advisable to seek medical attention so your doctor can assess the severity of the toxicity. They can also prescribe medication to manage immediate symptoms.

In cases of recent acute overdose, activated charcoal may be administered to bind vitamin A in the gastrointestinal tract and prevent further absorption.

Long-term management 

Once your vitamin A levels have returned to normal, your doctor will recommend strategies for managing your intake and avoiding recurrent episodes of toxicity. This could involve:

• Monitoring and adjusting your diet: Following a balanced diet that provides adequate vitamin A is key. Avoid consuming liver or other foods extremely high in vitamin A to reduce your risk of poisoning. Your doctor may also suggest consulting with a nutritionist to help you develop a balanced eating plan.

• Getting regular medical checkups: Schedule follow-up visits with healthcare providers to monitor your liver function and overall health after vitamin A poisoning. Blood tests may also be repeated to ensure vitamin A levels return to and remain normal.

What Happens If You Don’t Treat Vitamin A Poisoning?

Failing to treat vitamin A poisoning can lead to serious and potentially life-threatening health complications. These may include:

• Increased pressure in the skull: This can contribute to severe headaches, dizziness, and vomiting. If left untreated, this increased pressure can lead to permanent vision loss, brain damage, and even death.

• Organ damage: Acute toxicity can cause sudden and severe damage to the liver and kidneys, resulting in renal dysfunction. In chronic cases, this toxicity can also cause the liver to enlarge or develop fibrosis.

• Damage to the central nervous system (CNS): Symptoms of confusion, irritability, and lack of muscle coordination can worsen, leading to seizures or coma. 

• Increased risk of bone health issues: Chronic toxicity can increase your risk of fractures or developing conditions like osteoporosis.

• Increased risk of infection: Both chronic and acute toxicity can impair immune function, making the body more susceptible to infection.

• Impact on mental health: Chronic symptoms and physical discomfort can impact mental health, causing symptoms of anxiety and depression that can affect your overall quality of life. 

These potential complications highlight the importance of getting proper treatment for vitamin A poisoning under the guidance of a medical professional.

You can also consult your doctor about your individual risks and what you can do to avoid them.

Where Can You Learn More About Healthy Lifestyle Habits?

While vitamin A toxicity is rare, it’s important to be aware of the potential dangers of excessive vitamin A intake.

If you’re looking for more information on healthy lifestyle habits to improve your overall well-being, LifeMD has you covered.

We can connect you to a team of medical professionals who can help guide you on healthy habits — all from the comfort of your home. 

Make an appointment with LifeMD to take control of your health today.

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