The Difference Between Boosters and Drugs: Boosters are used to restore stats that you temporarily lose or "use up" -- health, stamina, psi energy, and HackNet energy. Other than that they cost some stamina to use (except for stamina boosters, obviously), they have no side effects. Drugs temporarily improve your character's stats above their normal level, usually for 5 minutes; they nearly always cause drug flash when they wear off, which I'll explain in a moment.
Food and Drink: Candy bars and soft drinks act like health boosters that slowly restore 10 to 20 health. Rats, snakes, bats, lizards, and dogs sometimes have cuts of meat that can be eaten raw, restoring 25, 50, or 100 health depending on the size of the piece of meat. (Watch out for Diseased or Rotten meat, which has the same icon as large pieces of meat.) Gourmet meals are expensive one-shot 100 health boosters.
Alcohol: The only pure intoxicant in the game, the various bottles of liquor give a boost of +50 to a non-existant stat, that only lasts for a few seconds. (There was a rumor that the actual stat boosted was Resist Force. I have seen no research to prove this, and I doubt it very much.) In other words, the booze exists only to create drug flash, to blur your vision, make you walk funny, and lay you out if you drink too much too fast.
Drug Flash: When most drugs wear off, there is a high percentage chance that you will experience drug flash. This causes your vision to blur, and makes you wobble when you walk, for several minutes at a time. Drug flash can temporarily cancelled by the "hair of the dog," taking another hit of the drug, but this only postpones the effect and makes it worse. The more drug flash effects you have going at once, the worse the effects will be. At around 5, you're nearly blind, and you no longer wobble, you actually crawl (are stuck in "crouch" mode). If you have enough drug flash effects going at once, it can kill you. (If someone offers to tell you a way to remove drug flash instantly, report them to firstname.lastname@example.org or email@example.com.)
Stacking: Taking another hit of the same drug before it wears off has no effect. The results do not stack. Some users report some luck using a second hit to extend the duration, but it hasn't always worked for me when I've tried it. I don't know whether it's random or if one of us is bugged. You can, however, stack multiple drugs that have similar effects. For example, taking one hit each of Serumderibat (+3 DEX), Whiteflash (+4 DEX), and Redflash (+5 DEX) will briefly give you +12 DEX ... and when they wear off, you'll get the drug flash for all three, of course.
Addiction: Drugs in Neocron are not technically addictive. However, it is pretty common for runners to use drugs to install implants that they otherwise couldn't use, wear armor they couldn't otherwise wear, or wield weapons they couldn't otherwise wield. When you pass through a genetic replicator, you will have to take another "hit" or do without your armor or implants; when the drug wears off, if that's your only weapon then you're not only in drug flash, you're disarmed. So you tell me, is this an addiction or not?
Buying Legal Drugs: The most common boosters and drugs are sold practically everywhere. There are Medicare shops in almost every sector of Neocron City and at the Military Base. There are Dragon Drug shops in some (but not enough!) sectors of the Dome of York. There are non-player character Medics who sell these drugs to members of their own faction inside each faction headquarters (although some of them are out of order). There are Drugstore Stuff street vendors and smugglers at about half of the Wastelands outposts and several small wastelands buildings and towns.
Manufacturing Drugs and Boosters: Most drugs and boosters can be manufactured by Engineers (constructors) from blueprints made by Scientists (researchers). However, the process is slow, and since the drugs and boosters that can be manufactured this way are all pretty cheap, hardly anybody bothers. (There are two exceptions that will be mentioned below, separately.) The more time-efficient way to make large quantities of these boosters and drugs is with the Recycling skill. Just use a Recycling Tool, enough Recycling skill to match the Tech Level of the item, and a large pile of garbage loot from things you've killed. Stick them all in your Processor (F7) window and hit start, take out the stack of drugs. The more expensive the drug, the more garbage, and more valuable garbage at that, it takes to make them. (Most people refer to this as "cloning" the drug.)
First Aid Kits and Medical Kits: These are slow +100 health boosters with multiple charges; 2 charges for the First Aid kit and 3 charges for the Medical Kit. These can be cloned and manufactured, and fairly cheaply at that.
Stamina Boosters: These disposable self-injectors instantly restore 255 stamina points. The only difference between the level 1 and level 2 boosters is that the level 2 booster has 4 charges. These can be cloned and manufactured.
Psi Boosters: These disposable self-injectors very quickly restore 100, 200, or 400 points of psi energy. Psi Booster 1 and 2 are easy to clone. Psi Booster 3, on the other hand, is not. This is an expensive booster, and it is almost impossible to shovel enough junk into a recycling tool to make even one of them. And since they're only TL20, any low-level researcher and constructor hybrid or team who have the patience can make good XP and some money manufacturing stacks of 249 Psi Booster 3s at a time for high-level psi monks.
Hack Boosters: These do for HackNet energy what Psi Boosters do for psi energy.
Antidotes: These drugs remove lasting negative effects, or "stacks" as they're sometimes called, that show up on the lower right corner of your screen. They are also available in more expensive "advanced" and "concentrated" versions that remove more of the effect but take slightly longer to work. Antidote drugs remove poison stacks. Antishock drugs remove parashock and freezer-gun effects. Damageblocker drugs remove damage-boost psi effects. Stealthblocker drugs let you cancel out of stealth-tool use more quickly. The legal status of these drugs isn't made clear in the game, but they are very hard to buy, sold only a very few places. (The only one I remember off-hand is an obscure drugstore sales counter at the Yo's Pawn Shop in Outzone sector 1.) They are fairly cheap, and can be cloned (and I assume, manufactured, but I haven't tried).
Performance-Enhancing Supplements: There are inexpensive one-shot drugs available all over the place that boost one or more of your stats. The cheapest, safest, and most common of them do nothing other than give you a roughly 5 minute slight boost to one of your primary stats: INT (Destrosol), DEX (Serumderibat), STR (Thyronol), CON (Paratemol), or PSI (Havenin). Most people collectively refer to these as the "+3 drugs," even though one of them (Paratemol) is actually +4.
There are also a whole bunch of cheap, legal drugs that temporarily boost one of your secondary stats, too many of them to list here. You can find a complete list at the Neocron Resource Site or Agent Hardy's Web Page. These are all cheap, easy to clone, legal, and available all over the place. Finally, there are the "resist boosters," which are not boosters in the sense above. Instead, these are stat-boosting drugs that give a 5-minute boost to your Resist Energy, Resist Fire, Resist Poison, or Resist X-Ray stats.
More Powerful OTC Medications: Then there are the more expensive drugs that give a slightly higher boost to one of your primary stats and two somewhat-related secondary stats. They all-but-one also have a "side effect," a minus to one of your secondary stats. These drugs can be manufactured, and can be cloned, just not as cheaply as the previous list of drugs. They are legal to buy over the counter everywhere, but (judging by what the non-player characters say) the abuse of them is frowned upon and they can only be legally sold by Medicare and by the medical personnel at your faction headquarters. Most players refer to these as the "+4 drugs." There are five of them:
Illegal Performance-Enhancing Drugs: Then there are what most players refer to as "the +5 drugs," which are even more powerful versions of the "+4 drugs" listed above. These drugs are illegal to manufacture, possess, use, or sell in Neocron City. However, there is no automatic enforcement of this rule, it's more of a role-playing guideline. (On the other hand, don't be surprised if some day the Event Game Masters step in and do something about people openly selling drugs.) So the only real effect this has on the game is that these drugs are only sold "over the counter" by Faction Supply Manager of the Black Dragon Society in the Dome of York, and only to Black Dragon members with a faction sympathy of 90 or higher. These can be cloned, but somewhat expensively; they can be manufactured for a smidgen under 2000 credits per dose. There are only four of them (no CON drug):
- X-Strong: Strength +4, Melee Combat +20, Resist Force +20, Vehicle Combat -20. The Street Samurai's friend; the only way for a low-level Street Samurai to survive tough fights.
- Whiteflash: Dexterity +4, Agility +13, Athletics +11, Melee Combat -20. This is an extremely useful drug for pistol and rifle users in close combat, where speed makes the difference between survival and death.
- Destrosol Forte: Intelligence +4, Weapon Lore +12, Willpower +12. This drug is somewhat useful to Assassins and Riggers; one hit will give you extended weapon range or extended flight range and speed.
- Dolinskin: Psi +4, Psi Use +12, Hacking +12, Weapon Lore -10. This drug makes psi monk spells faster, long-ranged, and more accurate; it can also make a big difference in effectiveness for a Hacker trying to get through a tough lock.
- Paratemol Forte: Constitution +4, Endurance +14, Health +10. Very popular with Soldiers and popular with many other runners for the significant improvement in survivability.
Dragon Drugs: These are highly illegal, very experimental drugs that have just been created by the Black Dragon Society. They're super-powerful versions of the "resist" drugs. Each one gives an incredible +150, enough to "max" the skill, to either Resist Force (Yellow Dragon), Resist Fire (Red Dragon), Resist Energy (White Dragon), Resist Poison (Green Dragon), or Resist X-Ray (Blue Dragon). There are side effects; they reduce your hit points by 50 and your stamina by 100. They can not be cloned or manufactured by players. They are only sold by the Supply Boss in the Black Dragon Society headquarters in the Dome of York, and only to members who have completed the Black Dragons' sixth and final epic mission.
- Beast: Strength +5, Heavy Combat +25, Agility +25, Weapon Lore -20. Does incredible things for Soldiers in close combat, boosting the heck out of their running speed and weapon damage at the expense of accuracy.
- Redflash: Dexterity +5, Athletics +17, Agility +22, Psi Use -10. Lets you scurry around like a cockroach on crack, at the expense of a skill that only matters for psi monks.
- Blue Fairy: Intelligence +5, Weapon Lore +18, Willpower +15, Athletics -10. Does more for Assassins and Riggers than Destrosol Forte does, but at a terrible cost in running speed.
- Nightspider: Psi +5, Psi Use +20, Implanting +16, Resist Force -15. Might give some advantage to Psi Monks in combat, but only at the expense of rendering them even weaker in the area where their armor is already at its weakest. Still, this is the most popular of the +5 drugs because that +16 Implanting bonus is really handy for getting in the highest level cybernetic implants.
Looted Drugs: There are four drugs that can not be cloned or manufactured, and can not be bought anywhere in game; they are only found (if at all) as loot on certain "bosses" in various caves.
Loss of Memory Pills: Ah, these are the truly "addictive" drugs in Neocron, even though they're perfectly legal and sold over the counter everywhere: Taylor Biochem in Neocron City and the Military Base, Dragon Drugs in the Dome of York, and by drugstore sellers at about half of the outposts in the Wastelands. (The latter are about 25% cheaper, by the way.) They sell for about 2000 credits per dose, and can not be cloned or manufactured by players. These are the drugs that let you "re-spec" your character. They do not cause "drug flash," oh no, they do something much worse: they give you 42% synaptic impairment. This takes about six to seven minutes to wear off, and you can't take another LOM until then. Each one removes 5 or 6 points from one of your subskills. It also costs you a percentage of your total experience in that primary skill, so if you take enough of them, the primary skill will drop and you'll temporarily lose those subskill points. Still, a long session of "LOMing" will let you switch your character's subskills all around, letting you (for instance) turn a Rigger into an Assassin, or an Engineer into a Scientist, or a Street Samurai into a Soldier.
- Kri'nakh Mushroom: Psi +5, Intelligence +10. Only dropped by the highest-level Kri'nakh Shaman in some (but not all) of the Swamp Caves.
- Kri'nakh Nightshade: Strength +10, Melee Combat +40, Agility +25, Weapon Lore -20. Same source.
- Crescent Tabs: Psi +7, Intelligence +13. Not currently available.
- Tiger Blood: Strength +7, Melee Combat +30, Agility +30. Not currently available, I think?