Drugs need to be done realistically. Drug use is often done REALLY badly in games. As someone who knows a thing or two about drugs and how they work, I implore you not to do this badly.
You essentially have two options:
1. Use real drugs in the game (either mention them or have them as a game mechanic), or
2. Use imaginary drugs in the game (this is less likely to get you censored, but requires a little more thought)
Real drugs:In a post-apocalyptic setting, synthetic drugs are going to be hard to come by for the most part. Making synthetic drugs requires chemicals that are hard to come by unless you have an industrialised civilization. LSD requires a very long and complex process to make, it would not be around. MDMA, methamphetamine, amphetamine, nitrous oxide, PCP and ketamine would not be around. Heroin would be rare even if opium poppies are available.
It is much more plausible that there will naturally occurring drugs. It is up to you to decide how fertile the wasteland is, which will decide what plants (and hence drugs) can grow there:
- Alcohol is easy to make if you have some excess sugar, grain or fruit. Think homemade beer and high-strength spirits.
- Opium is dried sap from opium poppies - very hardy plants. Opium contains morphine and codeine. Heroin is made by diacetylizing morphine, but this is impractical/not possible without industrialisation, and heroin is only more potent than morphine if you inject it (who will make the needles after the apocalypse?).
- Cannabis (marijuana) is a very hardy plant that is useful for more than just drugs. Up until 70 years ago, making things from hemp was extremely common - the first law in North America regarding cannabis was one that required all landowners to grow it. Ship sails, clothes, rope, sacks - even the draft copies of the US Constitution - were all made from hemp. You get the idea.
- Peyote and other types of cacti contain mescaline and grow in deserts.
- Khat is a hardy African plant that contains cathinone and methcathinone, strong stimulants similar to amphetamine.
- Coca grows in wet environments and can be chewed or brewed into tea for the cocaine it contains. Extracting the cocaine would be impractical post-apocalypse. Crack cocaine is a freebase form of cocaine - again you are unlikely to see it after the apocalypse.
- Coffee and tea grow well only in wet environments.
- Tobacco requires decent rainfall. Manufacturing cigarettes on a large scale requires a factory.
- Hallucinogenic mushrooms require decent rainfall.
Injecting drugs is just not practical without industrial civilization. Use a rusty needle and get tetanus. Use a second-hand needle and get hepatitis or HIV. Most drugs would be chewed, eaten or smoked.
Addiction is a VERY BAD THING. Without a proper social support network, an alcoholic is
every bit as bad as a meth-head or heroin junkie (or opium addict, or whatever).
Imaginary drugs:If you choose to create imaginary drugs (I have no problem with this in a fictional setting), you need to follow a couple of rules. First, drugs have actual chemical names. They are not called things like "Chemical X" because that's just silly. If you are going to use names like "Jet" make it clear that they are street names.
You shouldn't be able to take 500 doses of most drugs and survive. In the real world, 15 doses of meth, 10 doses of alcohol (around 50 drinks) or 6 doses of heroin will kill you. Too many depressants will cause coma and death. Too many stimulants will cause
deadly high blood pressure.
Third, drugs don't heal you to full health, they give status effects like increased stamina (stimulants), resistance to pain (morphine, heroin, marijuana) or resistance to anxiety and fear (benzodiazepines). Alcohol is an amazing disinfectant. A drug shouldn't be simultaneously a stimulant and depressant as this is very rare. Most hallucinogens don't make you see imaginary things, most of them just warp your perception - with the exceptions of deliriants.
TL;DR: Not all drugs are equal. Fully synthetic drugs will be hard to come by in the absence of industrial civilization. Some are more toxic than others - I should not be able to take 500 doses of most drugs and live. Some are more addictive than others. They all have different effects, but drugs do not "heal" people to full health. They have real names not stupid ones like "Chemical X".