Side Effects of Serotonin

Serotonin is a hormone secreted by blood platelets, the digestive tract and the pineal gland located in the brain. This chemical functions as a neurotransmitter that helps brain and other cells in the nervous system communicate with the body. Changes in the level of serotonin in the brain can affect an individual's mood. The use of selective serotonin re-uptake inhibitors (SSRIs) to control depression was first available in 1987. These medications appear to work by blocking the reuptake of serotonin, leaving more of the neurotransmitter available in the brain. Use of serotonin medications can result in side effects, some of which present a dangerous health risk.

Sexual Dysfunction

According to MayoClinic.com, individuals who use SSRI medications to treat depression may also experience reduced desire or difficulty with orgasms. An increase in serotonin tends to diminish sexual functioning and leads to decreased arousal, desire and orgasm.

Gastrointestinal

Serotonin affects the hypothalamus, which is responsible for control of appetite. According to the University Of Michigan Health System, side effects SSRIs and increased serotonin can include nausea, appetite changes and weight loss.

Neurological

According to MayoClinic.com, other side effects from an increased amount of serotonin hormone can include headache, nervousness, agitation, restlessness, drowsiness, fatigue and insomnia. While each of the medications used to increase serotonin and treat depression have the same general mechanism of action, each has different pharmacological characteristics. This means that individuals will not experience all of the neurological side effects with every SSRI medication; a patient may have unpleasant side effects with one of the antidepressants, but not another.

Serotonin Syndrome

When there is an excess of serotonin in the brain, there can also be an excess amount of nerve cell activity, causing signs and symptoms of serotonin syndrome. According to the American Headache Society, this possibility increases when the individual is also taking medications used to treat other neurological or medical conditions. According to Drugs.com, the U.S. Food and Drug Administration notified healthcare professionals in 2006 that individuals taking triptan medications to treat migraine headaches together with SSRI antidepressants would be at higher risk of developing a life-threatening condition called serotonin syndrome. Symptoms include increase in blood pressure, body temperature changes, confusion or agitation, hallucinations, tremors, muscle jerks or twitches, loss of coordination, increased reflexes, diarrhea, nausea and vomiting.

Cataracts

In a study published June 2010 in "Ophthalmology," researchers noted that although older generation antidepressants were associated with an increasing risk of cataracts, there were no population-based studies that had yet associated SSRI antidepressants with the condition. Evaluating over 18,000 individual medical histories between 1995 and 2004, researchers found that the risk of cataracts was highest in individuals using specific SSRI antidepressants. These were fluvoxamine and venlafaxine. The study was unable to control for smoking, leading the researchers to believe that further study is needed to evaluate the association.