Serotonin syndrome

Serotonin syndrome is a potentially life-threatening disorder in which the body has too much serotonin. Learn about the causes, symptoms, diagnosis, and treatment of serotonin syndrome in this article.

What is Serotonin?
Serotonin is a neurotransmitter, or a chemical that helps relay signals from one area of the brain to another. While the majority of the serotonin in the body is produced in the brain and stored there (about 90%), the rest is found in the digestive tract and in blood platelets. It is produced through a very unique biochemical process, beginning with the amino acid tryptophan; the cells that produce serotonin combine tryptophan hydroxylase and tryptophan, and voila, serotonin is formed. Because so many cells contain this neurotransmitter, it affects a lot of psychological and other functions. This includes mood, sexual desire and function, appetite, sleep, memory, learning, temperature regulation, and some social behavior; it can also have an effect on the functioning of the cardiovascular system, the muscles, and parts of the endocrine system. As you can see, this is a wide variety of functions and systems influenced by serotonin. It only makes sense that an abundance of serotonin can lead to serious problems in these areas.


There are different causes of serotonin syndrome, but they all result in the same thing: too much serotonin. In some cases, it can be caused by taking just one drug that increases serotonin levels, but most often, it is caused by combining such medications. Another common cause is the intentional overdose of antidepressant medications. Medications that can contribute, in one way or another, to serotonin syndrome are serotonin reuptake inhibitors (SSRIs),  which are antidepressants; serotonin and norepinephrine reuptake inhibitors (SNRIs), which are also antidepressants; bupropion, an antidepressant and tobacco addiction medication; monoamine oxidase inhibitors, another form of antidepressants; anti-migraine medications; pain medications; lithium, a mood stabilizer; illicit drugs, including cocaine, Ecstasy, amphetamines, and LSD; herbal supplements, including St. John’s Wort and ginseng; over-the-counter cough and cold medications; anti-nausea medications; linezolid, an antibiotic; and ritonavir, an anti-retroviral medications used to treat HIV/AIDS.


Symptoms of serotonin syndrome include agitation, restlessness, confusion, rapid heart rate, dilated pupils, loss of muscle coordination, twitching muscles, heavy sweating, diarrhea, headache, shivering, and goose bumps. Severe serotonin, which is life-threatening, has additional symptoms: high fever, seizures, irregular heartbeat, and unconsciousness.

If you experience any of these symptoms, contact a doctor or emergency medical help immediately.

Diagnosis and Treatment
The best way to diagnose serotonin syndrome is for the doctor to rule out other possibilities. Once a diagnosis is made, treatment can be started, but depends on the severity of your symptoms. If symptoms are minor, a visit to the doctor and cessation of taking the medication should be enough. If symptoms arise concern from your doctor, you will need to go to the hospital. If the symptoms are severe, you may need additional medications and a longer hospitalization period.

Possible Treatments
Muscle relaxants are given to help control agitation, seizures, and muscle stiffness. Serotonin-production blocking agents are used to block serotonin production. Oxygen and intravenous fluids can maintain normal blood oxygen levels and the IV fluids can treat dehydration and fever. Drugs that control heart rate and blood pressure are sometimes administered to reduce the heart rate and lower blood pressure. If you have a high fever, a breathing tube and machine and medication to paralyze your muscles may be necessary.

The symptoms should go away within 24 hours of starting treatment. However, if the syndrome was caused by antidepressant medications, symptoms can last for weeks because those medications stay in your system longer than other medications that can cause serotonin syndrome.

Last updated on Nov 12th, 2010 and filed under Neurological Disorders. Both comments and pings are currently closed.

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