What are the Most Common Serotonin Syndrome Symptoms?

Serotonin syndrome occurs when there is too much of the neurotransmitter serotonin in the brain. The likelihood of recovery depends upon the severity of the symptoms and how quickly treatment is sought. Medications, illicit drug use, and certain illnesses can cause excess serotonin to build up. Those with risk factors for serotonin syndrome should be aware of the symptoms and see their doctor if they notice anything out of the ordinary.

Serotonin syndrome symptoms can sometimes be so mild that they are hardly noticeable and are easily dismissed. Other people experience more noticeable symptoms. They may notice their heart rate increases suddenly or they may begin to shiver or sweat. Dilated pupils, tremors, or intermittent twitching are also commonly seen symptoms of serotonin syndrome. People experiencing serotonin syndrome symptoms are apt to feel confused, foggy headed, or may complain of a headache.

Those with moderate serotonin syndrome symptoms may be restless, agitated, or anxiously hypervigilant. They may experience an hypomanic episode in which they talk very fast, have racing thoughts, and cannot settle down. High blood pressure may be detectable in patients with moderate symptoms. An increase in body temperature, as high as 104° Fahrenheit (40° Celsius), is another symptom of moderate serotonin syndrome. Nausea, diarrhea, or an unsettled stomach with very active bowel sounds are other indications of this condition.

Severe serotonin syndrome symptoms can lead to death. Heart rate and blood pressure may increase to the point that the individual goes into shock or falls into a coma. Body temperature may rise to 106° Fahrenheit (41.1° Celsius). Temperatures this high can cause brain damage and lead to hallucinations, metabolic acidosis, seizures, kidney failure, blood clotting problems, or hemorrhaging.

Some over-the-counter, prescription, and illegal drugs known to increase serotonin levels in the brain can be causal factors in the development of serotonin syndrome symptoms. Those taking anti-depressants, such as Paxil, Effexor, and Wellbutrin, are often at risk of developing the syndrome. Herbal supplements, including ginseng and St. John's wort, are also known to raise serotonin levels. Certain thyroid conditions, as well as withdrawal from alcohol or heroin, may also cause serotonin syndrome.

Most people with serotonin syndrome make a full recovery. In mild cases, treatment consists of avoiding any medications that may be contributing to the condition. In cases of moderate or severe serotonin poisoning, the doctor will likely stop any problematic medications and then may administer a drug that counteracts the serotonin. The patient may also be sedated if he or she is agitated. People with risk factors for serotonin syndrome who think they are showing symptoms should seek medical attention right away.