Serotonin toxicity of serotonergic psychedelics
Summary & key facts
This paper is a careful review of past research about whether “serotonergic” psychedelics can cause dangerous rises in serotonin when mixed with other drugs that also affect serotonin. The authors looked at how serotonin toxicity happens, the signs to watch for, and which drug combinations seem risky. They say the worst form, called serotonin syndrome, usually shows up after an overdose or when a drug that raises serotonin is combined with a medicine that blocks the enzyme that breaks serotonin down. Psychedelics that do not contain those enzyme-blocking ingredients are generally low risk with other non-enzyme-blocking antidepressants, but some combinations could still be dangerous. The review points out clear warning signs that need urgent medical care and stresses that risk varies by the exact drugs and how they act in the brain.
- The authors reviewed existing studies and reports to understand when serotonin toxicity happens with psychedelics and other serotonin-affecting drugs.
- Serotonin syndrome, the most severe form of toxicity, most often occurs after an overdose or when a drug that raises serotonin is combined with a monoamine oxidase inhibitor, which is a drug that blocks the enzyme that breaks down serotonin.
- Psychedelics that do not contain monoamine oxidase inhibitors are generally low risk when combined with other psychiatric drugs that also do not contain those enzyme blockers.
- Dangerous signs that need immediate medical attention include sudden jerking movements, extreme swings in heart rate or blood pressure, very high fever, severe muscle stiffness, seizures, and very confused or unconscious states.
- The authors describe serotonin-related problems as a spectrum, from mild or temporary reactions up to full serotonin syndrome, so not every bad feeling is the most severe form.
- Because different psychedelics and psychiatric medicines change serotonin in different ways, some specific drug combinations may be risky while others are likely safe, and the evidence is still limited for many combinations.
