Combining several supplements or taking higher doses than recommended can increase the risk of harm. It is possible to get toxic doses of nutrients through supplements, but not through food. Vitamin D, calcium and folic acid are three nutrients that can be consumed in excess, especially through supplements. If you accidentally take two of your multivitamins on the same day, don't panic because you should be fine.
However, constantly taking too much of a supplement can be risky. A recent study found that calcium-rich foods may help protect heart health, but calcium supplements may increase the risk of plaque building up in the arteries and causing heart damage. Potassium supplements can also be problematic for the heart if taken too much. Vitamin A is another supplement that can cause hair loss, bone loss, confusion, and even liver failure if taken in excess.
Iron and zinc can also build up in the body and cause several problems. If you notice any digestive problems, nausea, vomiting, seizures, or a fast heart rate after taking a supplement, stop taking it immediately and call your doctor. It is important to talk to your doctor before taking any type of supplement to determine if it is necessary. Once the human body uses the vitamins and minerals it needs, the rest are excreted or stored.