Multiple vitamin overdose

Any ingredient in a multiple vitamin supplement can be toxic in large amounts, but the most serious risk comes from iron or calcium.

Additional risks are associated with large or toxic doses of calcium, vitamin D, and vitamin A.

Many multivitamin supplements are sold over-the-counter (without a prescription).

Iron overdose may include vomiting, diarrhea (which may be bloody or dark), or weakness. People with severe overdoses may develop coma, low blood pressure, liver failure, lung injury, and death.

Calcium overdose can impair the functioning of the kidneys, increase the pH of the blood, and can cause nausea and vomiting, confusion or changes in thinking or mentation, itching, and in extreme cases irregular heartbeat.

Vitamin D overdose can contribute to high levels of calcium in the blood.

Vitamin A overdose can cause nausea and vomiting, dizziness, blurry vision.

Additional symptoms of a multivitamin overdose in different parts of the body may include:

BLADDER AND KIDNEYS

• Cloudy urine
• Frequent urination
• Increased urine amount

EYES, EARS, NOSE, MOUTH, AND THROAT

• Dry, cracking lips (from chronic overdose)
• Eye irritation
• Increased sensitivity of the eyes to light

HEART AND BLOOD

• Irregular heartbeat
• Rapid heartbeat

MUSCLES AND JOINTS

• Bone pain
• Joint pain
• Muscle pain
• Muscle weakness

NERVOUS SYSTEM

• Confusion, mood changes
• Convulsions (seizures)
• Fainting
• Fatigue
• Headache
• Mental changes
• Irritability

SKIN AND HAIR

• Flushing (reddened skin) from niacin (vitamin B3)
• Dry, cracking skin
• Itching, burning skin, or rash
• Yellow-orange areas of skin
• Sensitivity to sun (more likely to sunburn)
• Hair loss (from long-term overdose)

STOMACH AND INTESTINES

• Intestinal bleeding (from iron)
• Appetite loss
• Constipation (from iron or calcium)
• Diarrhea, possibly bloody
• Nausea and vomiting
• Stomach pain
• Weight loss (from long-term overdose)

Seek medical help right away. DO NOT make a person throw up unless poison control or a health care professional tells you to.

Have this information ready:

• The person's age, weight, and condition
• The name of the product (ingredients and strengths, if known)
• Time it was swallowed
• The amount swallowed

Your local poison control center can be reached directly by calling the national toll-free Poison Help hotline (1-800-222-1222) from anywhere in the United States. This national hotline will let you talk to experts in poisoning. They will give you further instructions.

This is a free and confidential service. All local poison control centers in the United States use this national number. You should call if you have any questions about poisoning or poison prevention. It does NOT need to be an emergency. You can call for any reason, 24 hours a day, 7 days a week.

Take the container with you to the hospital, if possible.

Your health care provider will measure and monitor your vital signs, including temperature, pulse, breathing rate, and blood pressure. Symptoms will be treated. In severe cases, you may be admitted to the hospital.

Tests may include:

• Blood and urine tests
• Chest x-ray
• CT scan (advanced imaging) of the brain for neurologic symptoms
• Electrocardiogram (ECG)

Treatment may include:

• Activated charcoal
• Breathing support, including oxygen, tube through the mouth into the lungs, and breathing machine (ventilator)
• Fluids through the vein (IV)
• Laxative
• Medicines to treat symptoms

If medical treatment is quickly received, people who have iron and calcium overdoses usually recover. Overdoses of iron that cause coma or low blood pressure can sometimes be fatal. Iron overdoses can have long-term consequences to the intestines and liver, including intestinal scarring and liver failure.

Niacin flush (vitamin B3) is uncomfortable, but lasts only 2 to 8 hours. Vitamins A and D may cause symptoms when large doses are taken each day, but a one large dose of these vitamins is rarely harmful. B vitamins usually do not cause symptoms.

Aronson JK. Vitamins. In: Aronson JK, ed. Meyler's Side Effects of Drugs. 16th ed. Waltham, MA: Elsevier; 2016:435-438.

Theobald JL, Mycyk MB. Iron and heavy metals. In: Walls RM, ed. Rosen's Emergency Medicine: Concepts and Clinical Practice. 10th ed. Philadelphia, PA: Elsevier; 2023:chap 146.

Updated by: Jesse Borke, MD, CPE, FAAEM, FACEP, Attending Physician at Kaiser Permanente, Orange County, CA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.