Mixing Diphenhydramine (Benadryl) and GHB / GBL
Dangerous
Each makes the other much stronger, raising the risk of memory loss, collapse and unconsciousness. Do not combine. If someone passes out, put them on their side and watch their breathing.
Both substances are CNS depressants, potentiating each other strongly and unpredictably, raising the chances of memory loss, severe ataxia, and unconsciousness. The interaction will cause greater inhibition and risk of injury. If the user falls unconscious it is strongly recommended to put them into the recovery position and monitor breathing.
This combination carries bodily risk and can go badly psychologically. The headspace part often arrives first and makes the physical part harder to notice.
Headspace vs physical riskWhat to do
- Say what was taken and how much.Responders need it, and in most US states Good Samaritan laws protect both of you from drug possession charges when you call for an overdose.
- Unresponsive: put them on their side, tilt the head back, and stay until help arrives.Never leave someone alone to “sleep it off”.
- Never Use Alone 1-800-484-3731Stays on the line and sends help if you stop responding.
- Full steps: what to do if it is already happeningOverdose signs, the recovery position, what to say on the call, and whether you can be charged for making it.
- Poison Control 1-800-222-1222Free and 24/7, for “is this bad?” before it becomes an emergency.
Can you mix Diphenhydramine (Benadryl) and GHB / GBL?
MixSafe rates mixing Diphenhydramine and GHB / GBL as "Dangerous" — high risk of death or life-changing injury. Do not combine. Source: TripSit drug combination chart, retrieved 2026-08-20. Educational information, not medical advice.
- Diphenhydramine also called
- benadryl, dph, sleep aid, zzzquil, unisom, doxylamine
- GHB / GBL also called
- ghb, gbl, liquid ecstasy, 1,4-butanediol, bdo, 1,4-bd
TripSit drug combination chart, retrieved 2026-08-20. View the dataset.
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Rated dangerous. Educational information only, not medical advice. Absence of a documented interaction is not evidence of safety.