Evidence-based harm reduction information for commonly used substances. This content is provided for educational purposes and aligns with the practices of established harm reduction organizations. Not a substitute for medical advice.
If someone is unresponsive, breathing slowly or not at all: Call 911 (US) / 999 (UK) / 112 (EU) immediately. Administer naloxone if available. Good Samaritan laws protect callers in most US states. Do not leave the person alone. Time is critical — act first, ask questions later.
The most important rule for any substance. Begin with a fraction of the expected dose — typically 10–20%. Wait at least 90 minutes before considering redosing. Potency varies enormously across batches, sources, and substances. What was a standard dose before may be dangerous now.
Fentanyl contamination is documented in virtually every drug category — not just heroin. Fentanyl test strips (FTS) are a critical harm reduction tool for any powder, pill, or substance of unknown origin.
Having a trusted, sober person present is the most effective overdose prevention strategy. If using alone is unavoidable, the Never Use Alone hotline (1-800-484-3731, US) keeps you on the phone and can dispatch emergency services if you stop responding.
Combining certain substances dramatically increases risk even at individually safe doses. The TripSit combination chart (tripsit.me) is the standard reference for drug interaction risk levels.
tripsit.me/combo — Interactive combination chart covering hundreds of substance pairs. Color-coded risk levels: green (low risk), yellow (caution), orange (unsafe), red (dangerous/deadly).
Includes: heroin, fentanyl, oxycodone, hydrocodone, tramadol, morphine
Primary risks: Respiratory depression, overdose, physical dependence, withdrawal
Overdose signs: Unresponsive, slow/stopped breathing, blue lips, pinpoint pupils, gurgling sound
Response: Call 911, administer naloxone (2mg nasal spray or 0.4mg IM), perform rescue breathing, recover position, repeat naloxone every 2-3 minutes if no response
Key rules: Never mix with benzos or alcohol. Test for fentanyl always. Start at extremely low dose. Never use alone. Keep naloxone accessible.
HIGH DEPENDENCY RISK OVERDOSE RISKIncludes: cocaine, methamphetamine, amphetamines, MDMA, cathinones
Primary risks: Cardiovascular strain, overheating, sleep deprivation, psychological dependency, psychosis (with heavy use)
Key rules: Stay hydrated (but don't overhydrate — 500ml/hour max with MDMA). Take breaks to cool down. Avoid mixing with other stimulants. Do not redose heavily. Monitor heart rate. Take magnesium supplements with MDMA to reduce jaw clenching.
MDMA-specific: Test with Marquis (purple/black = MDMA present). Do not use more than once per month. Do not use with SSRIs — serotonin syndrome risk. Maximum session temperature: regular cool-down breaks.
CARDIOVASCULAR RISK OVERHEATING RISKIncludes: LSD, psilocybin mushrooms, DMT, mescaline, 2C-B
Primary risks: Psychological distress (challenging trips), HPPD, PTSD exacerbation in vulnerable individuals, accidents during impairment
Key rules: Set and setting are critical — ensure physical safety and positive mindset before starting. Have a trusted, sober trip sitter for high doses. Test with Ehrlich reagent (LSD turns purple). Do not use if predisposed to psychosis or schizophrenia. Avoid MAOIs with psilocybin/LSD. Start with low dose for a new substance or batch.
Challenging trip support: Change environment, use grounding techniques, breathe slowly. Benzodiazepines can interrupt a difficult experience. TripSit live chat offers real-time support.
SET/SETTING CRITICALIncludes: diazepam, alprazolam, clonazepam, etizolam, flualprazolam
Primary risks: Rapid physical dependence (even with short-term use), severe withdrawal (potentially life-threatening), overdose especially with opioids or alcohol, memory impairment
WARNING: Benzodiazepine withdrawal can cause fatal seizures. Never stop cold turkey after regular use. Medical supervision required for tapering. Substituting shorter-acting benzos for longer-acting ones (diazepam) is the safest taper method.
Key rules: Use as infrequently as possible. Never combine with opioids or alcohol. If dependent, seek medical guidance for taper. Never redose when unsure how much was taken — amnesia is common.
WITHDRAWAL DANGER DEPENDENCY RISKIncludes: flower, concentrates, edibles, oils
Primary risks: Cannabis-induced psychosis (dose-dependent, higher risk with high-THC products and genetic predisposition), dependency, impaired coordination
Edible-specific warning: Edibles take 45-120 minutes to reach peak effect. Many overdoses occur from redosing too early. Wait at least 2 hours before increasing dose. Edible dose is not proportional to smoked dose.
Key rules: Start with low THC concentration. High-CBD products reduce psychosis risk. Avoid if family history of psychosis or schizophrenia. Do not drive impaired — legal consequences and safety risk.
EDIBLE CAUTIONIncludes: ketamine, PCP, DXM, nitrous oxide
Primary risks: K-hole (ketamine dissociative state with loss of motor control), psychological dependency with ketamine, bladder damage with frequent ketamine use, suffocation risk with nitrous oxide
Key rules: Never use ketamine while standing, near water, or in unsafe environments. High doses intentionally — prepare safe horizontal position. Ketamine bladder syndrome develops with heavy daily use — abstain if urinary symptoms appear. With nitrous: use in seated position, avoid plastic bags over head (suffocation), limit session frequency.
BLADDER RISK (K) INJURY RISKNaloxone (brand: Narcan) is an opioid antagonist that reverses overdose within 2-3 minutes. It is available without prescription in most US states, UK pharmacies, and European harm reduction programs.
Naloxone sources: narcan.com, DanceSafe (dancesafe.org), local harm reduction organizations, many pharmacies without prescription.
For stimulants/psychedelics: Move to a calm, safe environment. Ground yourself — touch objects, breathe slowly, repeat your name and location. Have a sober friend present. Benzodiazepines can reduce anxiety and truncate psychedelic experiences. If panic or chest pain: call emergency services. For opioids: Call 911 immediately — have someone administer naloxone if available. Don't try to "sleep it off" — opioid overdose requires emergency medical intervention.
Fentanyl test strips (FTS) are reliable for detecting fentanyl in a sample, but have important limitations: a negative result (2 lines) does not guarantee the sample is safe — it means fentanyl was not detected in the tested portion. Hot spots in pressed pills mean the tested portion may differ from untested portions. FTS also cannot detect all fentanyl analogs (e.g., carfentanil may give false negative at standard dilution). Despite limitations, FTS are a valuable harm reduction tool and are recommended by public health authorities globally.
Yes. Addiction and physical dependence are pharmacological processes determined by the substance, dose, frequency, and individual biology — not by the source. Opioids and benzodiazepines can cause physical dependence within days to weeks of regular use. If you are struggling with substance use, resources include SAMHSA (1-800-662-4357), NHS services (UK), and local treatment centers. Seeking help is confidential in most jurisdictions.