Overview

Serotonin syndrome occurs when you take medications that cause high levels of the chemical serotonin to accumulate in your body.

Serotonin syndrome can occur when you increase the dose of such a drug or add a new drug to your regimen. Certain illegal drugs and dietary supplements also are associated with serotonin syndrome.

Serotonin is a chemical your body produces that's needed for your nerve cells and brain to function. But too much serotonin causes symptoms that can range from mild (shivering and diarrhea) to severe (muscle rigidity, fever and seizures). Severe serotonin syndrome can be fatal if not treated.

Milder forms of serotonin syndrome may go away within a day of stopping the medications that cause symptoms and, sometimes, taking drugs that block serotonin.

Source: http://www.mayoclinic.com

Symptoms

Serotonin syndrome symptoms usually occur within several hours of taking a new drug or increasing the dose of a drug you're already taking. Signs and symptoms include:

• Agitation or restlessness
• Confusion
• Rapid heart rate and high blood pressure
• Dilated pupils
• Loss of muscle coordination or twitching muscles
• Muscle rigidity
• Heavy sweating
• Diarrhea
• Headache
• Shivering
• Goose bumps

Severe serotonin syndrome can be life-threatening. Signs and symptoms include:

• High fever
• Seizures
• Irregular heartbeat
• Unconsciousness

When to see a doctor

If you suspect you might have serotonin syndrome after starting a new drug or increasing the dose of a drug you're already taking, call your doctor right away or go to the emergency room. If you have severe or rapidly worsening symptoms, seek emergency treatment immediately.

Source: http://www.mayoclinic.com

Causes

Excessive accumulation of serotonin in your body creates the symptoms of serotonin syndrome.

Under normal circumstances, nerve cells in your brain and spinal cord (central nervous system) produce serotonin that helps regulate your attention, behavior and body temperature.

Other nerve cells in your body, primarily in your intestines, also produce serotonin. In these other areas, serotonin plays a role in regulating your digestive process, blood flow and breathing.

Although it's possible that taking just one drug that increases serotonin levels can cause serotonin syndrome in susceptible individuals, this condition occurs most often when you combine certain medications.

For example, serotonin syndrome may occur if you take an antidepressant with a migraine medication. It may also occur if you take an antidepressant with an opioid pain medication.

Another cause of serotonin syndrome is intentional overdose of antidepressant medications.

A number of over-the-counter and prescription drugs may be associated with serotonin syndrome, especially antidepressants. Illicit drugs and dietary supplements also may be associated with the condition. These drugs and supplements include:

• Selective serotonin reuptake inhibitors (SSRIs), antidepressants such as citalopram (Celexa), fluoxetine (Prozac, Sarafem), fluvoxamine, paroxetine (Paxil) and sertraline (Zoloft)
• Serotonin and norepinephrine reuptake inhibitors (SNRIs), antidepressants such as trazodone, duloxetine (Cymbalta) and venlafaxine (Effexor)
• Bupropion (Wellbutrin, Zyban), an antidepressant and tobacco-addiction medication
• Tricyclic antidepressants, such as amitriptyline and nortriptyline (Pamelor)
• Monoamine oxidase inhibitors (MAOIs), antidepressants such as isocarboxazid (Marplan) and phenelzine (Nardil)
• Anti-migraine medications such as triptans (Axert, Amerge, Imitrex), carbamazepine (Tegretol) and valproic acid (Depakene)
• Pain medications such as opioid pain medications including codeine (Tylenol with codeine), fentanyl (Duragesic), hydrocodone meperidine (Demerol), oxycodone (Oxycontin, Percocet, Percodan) and tramadol (Ultram).
• Lithium (Lithobid), a mood stabilizer
• Illicit drugs, including LSD, Ecstasy, cocaine and amphetamines
• Herbal supplements, including St. John's wort, ginseng and nutmeg
• Over-the-counter cough and cold medications containing dextromethorphan (Delsym, Mucinex DM, others)
• Anti-nausea medications such as granisetron, metoclopramide (Reglan), droperidol (Inapsine) and ondansetron (Zofran)
• Linezolid (Zyvox), an antibiotic
• Ritonavir (Norvir), an anti-retroviral medication used to treat HIV/AIDS

Source: http://www.mayoclinic.com

Diagnosis

No single test can confirm a serotonin syndrome diagnosis. Your doctor will diagnose the condition by ruling out other possibilities.

Your doctor will likely begin by asking about your symptoms, medical history and any medications you're taking. Your doctor will also conduct a physical examination.

To make sure your symptoms are caused by serotonin syndrome and not due to another cause, your doctor may use tests to:

• Measure levels of any drugs you're using
• Check for signs of infection
• Check body functions that may be affected by serotonin syndrome

A number of conditions can cause symptoms similar to those of serotonin syndrome. Minor symptoms can be caused by numerous conditions. Causes of moderate and severe symptoms include:

• Anticholinergic syndrome, malignant hyperthermia and neuroleptic malignant syndrome, serious conditions caused by certain medications
• An overdose of illegal drugs, antidepressant medications or other medications that increase serotonin levels
• Damage (toxicity) associated with illegal drug use
• Severe alcohol withdrawal

Your doctor may order tests to rule out other causes of your symptoms. Tests may include:

• Blood and urine tests
• Chest X-ray
• Computerized tomography
• Spinal tap (lumbar puncture)

Source: http://www.mayoclinic.com

Complications

Serotonin syndrome generally doesn't cause any problems once serotonin levels are back to normal.

If left untreated, severe serotonin syndrome can lead to unconsciousness and death.

Source: http://www.mayoclinic.com

Prevention

Taking more than one serotonin-related medication or increasing your dose of a serotonin-related medication increases your risk of serotonin syndrome.

Talk to your doctor about possible risks. Don't stop taking any such medications on your own. If your doctor prescribes a new medication, make sure he or she knows about all the other medications you're taking, especially if you receive prescriptions from more than one doctor.

If you and your doctor decide the benefits of combining certain serotonin-level-affecting drugs outweigh the risks, be alert to the possibility of serotonin syndrome.

Risk factors

Some people are more susceptible to the drugs and supplements that cause serotonin syndrome than are others, but the condition can occur in anyone.

You're at increased risk of serotonin syndrome if:

• You recently started taking or increased the dose of a medication known to increase serotonin levels.
• You take more than one drug known to increase serotonin levels.
• You take herbal supplements known to increase serotonin levels.
• You use an illicit drug known to increase serotonin levels.

Source: http://www.mayoclinic.com