Although multivitamins are generally safe when you take them as directed, taking too much can result in toxicity. Multivitamins typically contain a number of different vitamins and minerals. Some vitamins are safe to consume in large quantities, but many are not. If you believe you or someone you know has taken too much of a multivitamin, call a doctor immediately or head to the nearest emergency room.
Recommended Amounts
When taking a multivitamin supplement, most people should stay as close to the recommended daily value amounts as possible. Whenever you exceed more than the tolerable upper intake level established for each vitamin or mineral, your risk of experiencing an adverse reaction increases. The tolerable upper intake levels vary according to age and gender, but most adults should not exceed more than 100 mg of vitamin B-6, 2,000 mg of vitamin C, 3,000 mcg of vitamin A, 1,000 mcg of folic acid, 100 mcg of vitamin D and 1,000 mg of vitamin E. Most adults also should not get more than 2,000 mg to 2,500 mg of calcium, 10,000 mcg of copper, 10 mg of fluoride, 1,100 mcg of iodine, 45 mg of iron, 350 mg of magnesium, 11 mg of manganese, 1.0 mg of nickel, 2,000 mcg of molybdenium, 400 mcg of selenium, 1.9 mg of vanadium, 40 mg of zinc, 2.3 g of sodium or 3.6 g of chloride. There are no established tolerable upper intake levels for the vitamins B-12, thiamine, pantothenic acid, riboflavin, biotin, vitamin K or choline.
Considerations
Biological factors, medical conditions, medications and dietary intake are just a few factors that can influence how much of a vitamin or mineral a person can safely take. Although the upper tolerable level amounts are useful as guidelines, some people may experience negative effects when less than these amounts are consumed, while others may be able to take much more with no discernible effects. The risk of experiencing adverse side effects increases proportionally to the amount you consume.
Symptoms of a Vitamin Overdose
Many unpleasant side effects may occur when you take too much of a multivitamin supplement. Symptoms of toxicity that may occur right away include itching, gastrointestinal upset, fatigue, changes in mood, rapid or irregular heartbeat, vision changes, confusion, muscle pain, joint pain, headaches, rashes or flushing, increased urination or seizures. Symptoms that may occur when large amounts of a multivitamin are taken over time include cracked or dry lips, weight loss and hair loss.
Warning
People who display symptoms of a vitamin overdose should seek immediate medical attention. Call the National Poison Control Center at 1-800-222-1222 or go to the nearest emergency room. At the hospital, doctors may conduct blood tests to check vitamin levels, give medicine to reverse the effects of an overdose or place a tube in the stomach through the mouth to remove the contents of the stomach. If medical treatment is quickly received, most patients with a vitamin overdose can recover.
Concerns about Children
Although some people deliberately take more than the recommended amount of a multivitamin, accidental overdoses may also occur, particularly in children. Some multivitamin supplements resemble candy, so it is crucial that parents keep multivitamin supplements out of the reach of young children and clearly explain the dangers of taking too many to older children.
References
- "The American Journal of Clinical Nutrition"; What is Known About the Safety of Multivitamin-Multimineral Supplements for the Generally Healthy Population; Catherine A. Mulholland; January 2007
- Institute of Medicine of the National Academies: Dietary Reference Intakes: Tolerable Upper Intake Levels, Vitamins
- MedlinePlus: Multiple Vitamin Overdose
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