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 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.