These calculators model pharmacokinetic behaviour based on published clinical data. They are educational tools — not medical advice. Accurate information reduces harm more effectively than abstinence messaging. All sources are listed on the Sources page.
Substance calculators
Alcohol
BAC simulation using the Widmark model. First-order absorption and zero-order elimination with sex and weight adjustments.
MDMA
1-compartment plasma model with CYP2D6 autoinhibition. Serotonin syndrome risk overlay and redosing guidance.
Cannabis
THC plasma model for smoked and oral routes. Active metabolite 11-OH-THC tracked separately. Route comparison.
Cocaine
Intranasal 1-compartment PK model. Cocaethylene formation on combined alcohol use. Cardiovascular risk zone overlay.
Amphetamines
Oral amphetamine and methamphetamine with pH-dependent elimination. Vitamin C acidification comparison.
Ketamine
2-compartment intranasal model with dissociation threshold zones. K-hole concentration range visualised.
Cathinones
Mephedrone plasma concentration model with wide uncertainty band. Information cards for other synthetic cathinones.
Resources
Interaction checker
Severity matrix for recreational and prescription drug combinations — mechanism, serotonin syndrome risk, respiratory depression.
PK graph guide
Plain-English explanation of concentration-time curves for non-scientists. What Cmax, Tmax, half-life, and AUC actually mean.
Support & Information
If you or someone you know is in crisis, please reach out to one of the services above or contact your local emergency services.