Serotonin syndrome is a serious drug reaction. It is caused by medications that build up high levels of serotonin in the body. Serotonin is a chemical that the body produces naturally. It's needed for the nerve cells and brain to function. But too much serotonin causes signs and symptoms that can range from mild (shivering and diarrhea) to severe (muscle rigidity, fever and seizures). Severe ...
