Interactive harm reduction

Mixing Drugs

Choose two or more substances to see the main overlapping effects and risk signals. This is an educational interaction guide, not a personalised medical assessment.

TD ConsultancyPublished 5 August 2026Reviewed 5 August 2026Curated UK safety guidance

Never use “no known interaction” as permission to mix drugs.If someone cannot be woken, has a seizure, severe chest pain, dangerous overheating or abnormal breathing, call 999.

Select 2–4 substances

This tool gives general risk information only. It does not ask how much you took and it does not provide medical clearance or dosing advice.

Interaction overview

Highest-concern combinations are shown first.

Opioids + Benzodiazepinesparticularly high risk

Overlapping sedation and respiratory depression

Main concerns

Profound sedation
Respiratory depression
Loss of consciousness
Aspiration

Safer response

Avoid the combination. If someone is difficult to wake or not breathing normally, call 999. Give naloxone if an opioid overdose is suspected and naloxone is available.

The absence of a recorded interaction does not mean that a combination is safe.

Strength, dose, health, tolerance, contamination, prescription medicines and other substances can alter risk. If this concerns something already taken and symptoms are severe or worsening, call 999. For medicine-specific advice, ask a pharmacist, prescriber or NHS 111.

How to read the results

Particularly high risk is used for combinations where overlapping effects can produce rapid, life-threatening harm — especially multiple depressants affecting consciousness and breathing.

Increased risk means known overlapping effects can intensify harm. Limited evidence means the public tool cannot give a confident interaction summary; it never means the combination is low risk.

Seek specialist medical advice is used where medicine-specific interactions cannot be safely generalised. Do not stop or change a prescribed medicine in order to take a recreational drug.