"Is too much or too little serotonin a problem? I want to know."

 Serotonin levels that are too low can show up as fatigue, irritability, and may be linked with depression. Levels that are too high are linked with osteoporosis and a downward slide in your libido. Excessive levels can lead to Serotonin Syndrome. This can occur when the central nervous system is overloaded with serotonin and cannot function properly. It can lead to seizures, difficulty breathing, kidney failure, coma, and even death. Some prescription and over-the-counter drugs can raise serotonin levels alone or in combination with others. Some recreational drugs (e.g., LSD, cocaine) and some dietary supplements (St. John’s Wort, ginseng), reportedly can also cause serotonin syndrome when taken with specific antidepressants. Bottom line: avoid messing with serotonin. Talk with your physician for questions and clarification.