Vitamins are a class of trace organic substances that humans and animals must obtain from food in order to maintain normal physiological functions, and play an important role in human growth, metabolism and development. Generally there are no side effects when consumed in moderation, but overdose may lead to adverse results. Specific examples are as follows: 1. Fat-soluble vitamins, such as vitamin A, vitamin D, and vitamin E, can coexist with lipids in the body. Overdose may lead to dry hair, muscle weakness, loss of appetite, irritability and depression. 2. Water-soluble vitamins, such as B vitamins, vitamin C, etc. Such vitamins are easily soluble in water. If water-soluble vitamins are taken in excess, some of them may not be able to be excreted in the urine, which may lead to neurological disorders, flushing of the skin, anxiety and restlessness, irritability, stones, hemolysis and other side effects. In addition, an overdose of vitamin C while taking anticoagulant medication may also affect the effectiveness of the anticoagulant. These are just a few of the more common dangers of vitamin overdose, and it is recommended that you take vitamins under the guidance of your doctor and do not overdose.