What is Serotonin Syndrome?

Serotonin is a natural substance produced by the body. It's crucial for nerve cells and the brain to function.

The Mayo Clinic reports that serotonin syndrome occurs when an individual takes medications that cause high levels of the chemical to accumulate in the body. It might occur when a drug dosage increases or when a new drug joins the ones a patient is already taking. Specific illicit drugs or dietary supplements can also be the culprit.

Symptoms

Signs of serotonin syndrome usually show up within a few hours after a patient takes a new drug or increases the dose of one he or she is already taking. Common symptoms include agitation, restlessness, confusion, a rapid heart rate and dilated pupils. Some patients experience a loss of muscle coordination or twitching muscles. Heavy sweating, diarrhea, headache, shivering and goose bumps sometimes occur.

Some cases of serotonin syndrome can be life-threatening. They're usually marked by high fever, seizures, irregular heartbeat and even unconsciousness.

The Mayo Clinic cautions that if an individual suspects serotonin syndrome after beginning to take a new drug or after upping the dosage of a current one, it's important to contact his or her physician right away or to visit a hospital emergency room. If the symptoms are severe or are worsening quickly, immediate emergency treatment is indicated. Severe serotonin syndrome can result in unconsciousness or death if untreated.

Causes

Serotonin is important in regulating a person's attention, behavior and body temperature. Nerve cells located in the brain as well as the spinal cord produce this substance, as do nerve cells elsewhere in the body, primarily in the intestinal tract. Serotonin produced in these other areas helps regulate digestion, blood flow and breathing.

For some patients, taking just one drug that raises the level of serotonin the body can cause the syndrome. Usually, however, it happens when an individual combines medications. If, for example, a patient takes an antidepressant plus medicine for a migraine, there could be a problem. Many instances of serotonin syndrome are due to intentional overdoses of antidepressants.

A number of drugs can cause an overload of this chemical. Among the most common are serotonin reuptake inhibitors (SSRIs), which are antidepressants marketed under names like Celexa, Prozac, Sarafem, Paxil and Zoloft. Serotonin syndrome is also associated with serotonin and norepinephrine reuptake inhibitors (SNRIs) such as trazodon and Effexor. Among the other antidepressants that can be to blame are the brand names Wellbutrin, Zyban, Marplan and Nardil.

Several anti-migraine medicines and pain medications can cause the syndrome. Taking lithium and certain anti-nausea medications and even herbal supplements like St. John's wort and ginseng can cause issues. Patients have also experienced serotonin levels that are too high after using illicit drugs like LSD, Ecstasy, cocaine or amphetamines. Cough and cold medications containing dextromethorphan are also on the list.

Risk Factors

Although anyone can develop serotonin syndrome, some people appear to be more at risk than others. They include patients who recently started taking or upped the dose of a new medication known to increase serotonin levels in the body. Also are risk are those who take more than one drug or any herbal supplements known to increase serotonin levels. Using an illicit drug associated with elevating levels of the chemical also puts individuals at greater risk.

Diagnosis

Doctors diagnose serotonin syndrome by ruling out other possible conditions. There is no specific test for the condition.

After taking the patient's medical history, a physician might order tests to measure the levels of any drugs being taken, check the level of thyroid hormone and examine body functions that the syndrome could affect.

A number of other conditions can cause similar symptoms. Among them are certain thyroid conditions, medication overdoses and withdrawal from heroin or alcohol.

Treatment

Doctors base treatment upon severity of symptoms. For some patients, stopping the medication that's the cause will make the problem to disappear. Others might need to stay in the hospital a few hours or be admitted for a longer stay.

Individuals treated for serotonin syndrome typically receive muscle relaxants, agents to block serotonin production, oxygen, intravenous (IV) fluids and medications to control heart rate and blood pressure. Those who have a high fever might require a breathing tube and machine as well as medication to paralyze muscles.

Source:

Mayo Clinic site