Mixing: cannabis with alcohol, tobacco and medicine

Cannabis on its own, in a reasonable amount, is a fairly predictable thing. Most of the evenings that go badly involve something else in the mix — and the combinations are predictable too, which means they are avoidable.

Alcohol

The most common pairing and the one that catches most people out. Two things happen.

The first is chemical: drinking first raises how much THC reaches the blood, so the same amount of cannabis lands harder after a few drinks than it would sober. The second is that neither substance tells you this is happening. Alcohol removes the judgement you would use to slow down, and cannabis arrives on top of that.

The result — nausea, cold sweat, the room moving, sometimes being sick — is the thing everybody has a story about. It is unpleasant and it usually passes with time, water and lying still somewhere quiet, but it is a genuinely miserable few hours.

Reverse order is not much better: cannabis makes some people notably worse at tracking how much they have drunk.

If you are going to do both, go slowly on both, leave real time between them, and treat your usual amount as too much.

Tobacco

Rolling cannabis with tobacco is normal in much of the world and worth thinking about anyway. It adds nicotine — which is the genuinely addictive part of the arrangement — to a habit you may not think of as a nicotine habit at all. People who stop mixing frequently report that what they were actually finding hard to give up was the tobacco.

It also adds tobacco's own harms to the smoke, which is a poor trade for a plant already being combusted. If the point is a slower burn, there are tobacco-free alternatives; the ways to use cannabis piece covers the options that skip smoke entirely.

Prescription medicine

This is the one that genuinely matters, and the one least often asked about.

Cannabinoids are processed by the same liver enzymes that handle a great many medicines, so cannabis can raise or lower the level of a drug in your blood without anything feeling different. Categories worth a specific conversation:

• Sedatives — benzodiazepines, sleeping tablets, opioids, and anything else that makes you drowsy. The effects add up, and breathing and alertness are what suffer.
• Blood thinners, warfarin in particular, where a changed blood level is a real bleeding risk.
• Anti-epileptic medicines, where CBD especially is known to interact and dosing is finely balanced.
• Psychiatric medicines, both for interaction and because cannabis can affect the condition being treated — see cannabis and mental health.
• Anything with a narrow margin between a working dose and a harmful one. If your doctor monitors your blood levels for a medicine, assume cannabis is relevant to it.

Ask a pharmacist. It is free, it takes two minutes, they are not there to judge you, and it is precisely the question they are qualified for. "I use cannabis, does that touch anything on this list" is the whole conversation.

The short version

One thing at a time, and know what you have taken. Nearly every genuinely bad experience people describe comes down to a combination nobody planned, at an amount nobody measured, on an evening nobody expected to be talking about afterwards.