Centrum Multivitamin/Multimineral is a balanced supplement that contains the full complement of vitamins and minerals you need to maintain health. It provides 100 percent of your daily requirement of 13 individual ingredients, with lower concentrations of others that are commonly found in large quantities in food. The normal dose of one tablet per day is safe, but overdoses can occur. Most vitamins don't cause a problem in these cases, but too much calcium or iron can be dangerous.
A single Centrum tablet contains 100 percent of your daily niacin and vitamin D, and 70 percent of your vitamin A. Taking more than one tablet technically counts as an overdose, but these vitamins won't cause a problem unless the high dose is repeated for long periods of time. The niacin may cause a temporary flushing sensation, but this will go away within about 8 hours, according to the University of Maryland Medical Center. Centrum also contains 100 percent of most of your B vitamin requirements, but any excess B vitamin in your body just gets excreted.
Calcium and Iron
The real danger of a Centrum overdose comes from the calcium and iron. A single tablet contains 200 mg of calcium and 18 mg of iron; the iron dose is the full recommended daily amount for adult women, and 10 mg over a man's daily need. The calcium dose is only 20 percent of your daily need, because you also get calcium from dairy and vegetables in your diet. Too much of either of these minerals can cause major health problems, even from a single dose; according to the Centrum label itself, iron overdose is the leading cause of poisoning death in children under 6, so keep your vitamins out of reach of children.
The list of multivitamin overdose symptoms is long, and can depend upon the exact formulation and the amount taken. Look out for rapid or irregular heartbeat; bone, joint and muscle pain; confusion; fatigue; weakness and fainting. Nausea, diarrhea and stomach pain can occur, and severe cases can result in convulsions and liver damage. If too much is taken for extended periods, symptoms like hair loss, sun sensitivity, cracked lips and weight loss may be apparent.
What to Do
If you suspect a Centrum overdose and symptoms are not yet apparent, call the National Poison Control Center at (800) 222-1222. If symptoms are occurring, call 911. According to the University of Maryland Medical Center, it takes a dose 50 to 100 times above the recommended dose of iron to cause a severe reaction, and calcium is considered an overdose when it exceeds 2,500 mg from all sources, including food. But even a mild reaction necessitates medical treatment, so don't wait for symptoms to occur before seeking help.