Drug interactions are the most under-discussed topic in psychedelic harm reduction. Many people who would never skip testing their substances give little thought to what those substances will do alongside the medications they take daily.
This is a significant oversight. Some combinations are merely inconvenient. Others are life-threatening.
The high-risk combinations
Three categories of medication deserve particular caution with serotonergic psychedelics.
Lithium is the most dangerous. Case reports and clinical experience consistently associate lithium combined with classical psychedelics — particularly LSD and psilocybin — with seizures and cardiac events. This is not a theoretical concern. It is a documented, recurring pattern. If you are taking lithium, classical psychedelics are contraindicated.
MAOIs create a different but equally serious risk profile. Ayahuasca contains MAOIs by design, but combining synthetic MAOIs with other psychedelics — or combining ayahuasca with serotonergic medications — risks serotonin syndrome, a potentially fatal condition characterised by hyperthermia, rigidity, and autonomic instability.
SSRIs and SNRIs are the most commonly encountered interaction. They generally blunt the effects of classical psychedelics rather than creating acute danger, but the interaction is more complex than simple attenuation. Abruptly discontinuing SSRIs to “make the psychedelic work” introduces its own serious risks, including discontinuation syndrome and rebound depression.
What to do about it
The single most important step is honest disclosure. If you are working with a facilitator, therapist, or guide, they need a complete medication list — not the list you think is relevant, but the complete list. If you are working independently, use a reliable interaction checker and err on the side of caution.
Never adjust psychiatric medication without medical supervision, regardless of what you read online about optimising psychedelic experiences.
Use the Interaction Checker to review specific substance pairs, or see the full Assessment guide for comprehensive safety screening.