Serotonin Syndrome

What is serotonin syndrome?

Serotonin syndrome is a medical emergency that occurs when there is too much serotonin activity in the central and peripheral nervous system. It typically results from combining two or more substances that increase serotonin signaling through different mechanisms.

Serotonin syndrome ranges from mild (discomfort) to life-threatening (organ failure) and requires immediate medical attention in severe cases.

Symptoms

Mild

• Agitation and restlessness
• Tremor (especially in hands)
• Dilated pupils
• Diarrhea
• Rapid heart rate
• Increased sweating
• Muscle twitching (myoclonus)

Moderate

• All mild symptoms intensified
• High blood pressure
• Hyperthermia (elevated body temperature)
• Hyperreflexia (exaggerated reflexes)
• Clonus (involuntary rhythmic muscle contractions, especially in ankles)
• Confusion and disorientation

Severe (life-threatening)

• Temperature above 41°C (106°F)
• Seizures
• Irregular heartbeat
• Rhabdomyolysis (muscle breakdown)
• Organ failure
• Loss of consciousness

If you or someone you're with shows moderate to severe symptoms, seek emergency medical care immediately.

The risk in microdosing context

Classical psychedelics alone

Classical psychedelics (psilocybin, LSD) at microdose levels have a very low risk of causing serotonin syndrome on their own because:

• They are receptor agonists (they activate receptors directly) rather than serotonin releasers
• At microdose levels, receptor activation is minimal
• They don't significantly increase overall serotonin levels in the synapse

The dangerous combinations

Serotonin syndrome risk increases dramatically when psychedelics are combined with:

HIGH RISK:

• MAOIs (monoamine oxidase inhibitors) — dramatically increase serotonin by preventing its breakdown. Combining MAOIs with psychedelics is the most dangerous common interaction.
• Lithium — can cause seizures and serotonin-related complications with psychedelics. Absolute contraindication.

MODERATE RISK:

• SSRIs (fluoxetine, sertraline, etc.) — increase synaptic serotonin. Risk with microdose psychedelics is theoretically low but not zero.
• SNRIs (venlafaxine, duloxetine) — similar mechanism to SSRIs
• Tramadol — opioid with serotonergic properties
• St. John's Wort — herbal supplement with serotonergic activity
• MDMA — serotonin releaser; risk is higher than with classical psychedelics

LOWER RISK (but not zero):

• Triptans (migraine medications) — act on serotonin receptors
• Dextromethorphan (cough suppressant) — weak serotonin reuptake inhibitor
• 5-HTP / L-tryptophan — serotonin precursor supplements

What to do

Prevention

1. Know your medications — make a complete list of everything you take, including supplements
2. Research interactions — check every medication for serotonergic properties
3. Consult a professional — especially if you're on any psychiatric medication
4. Don't combine serotonergic substances without expert guidance
5. Observe washout periods — when switching from one serotonergic substance to another

If symptoms appear

1. Stop all serotonergic substances immediately
2. Seek medical attention — especially if symptoms are moderate or severe
3. Tell medical staff exactly what you took, when, and how much (don't withhold information out of fear of legal consequences — medical staff are there to help you, and your health comes first)
4. Cool down — remove excess clothing, apply cool cloths if body temperature is elevated
5. Hydrate — drink water if conscious and able to swallow

Medical treatment

In clinical settings, serotonin syndrome is treated with:

• Cyproheptadine — a serotonin antagonist that blocks excess serotonin activity
• Benzodiazepines — for agitation and muscle rigidity
• Active cooling — for hyperthermia
• IV fluids — for hydration and temperature management