What is Serotonin?

Serotonin is a neurotransmitter, sometimes referred to as the “feel-good” chemical. It helps regulate mood, sleep, digestion, and other vital functions. Most serotonin is actually produced in the intestines, but it also plays an important role in the brain by transmitting messages between nerve cells.

Causes of Serotonin Syndrome

Serotonin Syndrome happens when too much serotonin builds up in the body. This can occur through medications, supplements, recreational drugs, or certain health conditions. Some common causes include:

• Antidepressants: SSRIs, SNRIs, MAOIs, Tricyclics.
• Migraine Medications: Triptans.
• Pain Medications: Tramadol, Fentanyl.
• Over-the-Counter Medicines: Cough and cold remedies containing Dextromethorphan.
• Herbal Supplements: St. John’s Wort, Ginseng.
• Recreational Drugs: MDMA (Ecstasy), LSD, Cocaine.
• Underlying Health Conditions: Rare illnesses such as carcinoid syndrome can also raise serotonin levels.

Signs of Serotonin Syndrome

Signs usually appear very quickly – often within a few hours – after starting a new medicine, taking a bigger dose, or mixing medicines that affect serotonin. They can be mild or serious and are often grouped into three areas:

In very bad cases, these signs can lead to fits (seizures), a very high temperature, uneven heartbeat, passing out, or even death. If someone suddenly gets very confused, has a fit, or has an extreme fever after taking medicine, call emergency services straight away.

How Is It Diagnosed?

Serotonin Syndrome can be tricky to diagnose because its symptoms overlap with other conditions. Doctors typically:

• Review Medical History: Especially recent medication changes or drug use.
• Perform a Physical Examination: Checking for neuromuscular signs like tremors or hyperreflexia.
• Apply Diagnostic Criteria: Tools like the Hunter Serotonin Toxicity Criteria or Sternbach Criteria help confirm diagnosis.

How Is It Treated?

Treatment depends on how severe the symptoms are, but most people recover fully if they receive prompt care.

Mild Cases:

• Stopping the medication causing the problem.
• Supportive care such as hydration, rest, and monitoring.

Moderate to Severe Cases:

• Hospital admission for observation and treatment.
• Intravenous fluids to stabilise the body.
• Medications like benzodiazepines to ease agitation and prevent seizures.
• Serotonin blockers such as cyproheptadine to counteract excess serotonin.

Critical Cases:

• Intensive care unit (ICU) support.
• Cooling measures for dangerously high body temperature.
• Mechanical ventilation if breathing becomes compromised.

Prevention

Serotonin Syndrome can often be prevented with careful medication management and awareness of risks:

• Medication Review: Regularly discuss all medications and supplements with your doctor or pharmacist.
• Educate Yourself: Understand which drugs raise serotonin levels and why combining them can be risky.
• Monitor Changes: Watch for new symptoms when starting or adjusting doses.
• Avoid Risky Combinations: Only combine serotonergic drugs under close medical supervision.
• Never Stop Suddenly: Don’t stop or change medications abruptly without medical advice — this can trigger withdrawal or complications.

Living with Serotonin Syndrome

If you’ve experienced Serotonin Syndrome, it’s vital to take steps to prevent it happening again:

• Communicate Clearly: Tell every doctor or pharmacist about your history before starting new treatments.
• Wear Medical Alert Jewellery: This alerts emergency staff to your condition if you can’t speak for yourself.
• Keep a List: Write down all medications and supplements you take and update it regularly.
• Regular Check-ups: Stay in touch with your healthcare provider for ongoing medication reviews and safety checks.