Yeah, thats a good idea, we need to keep it realistic, having too much drugs should have a negative effect.
PiMP, you just made me remember something. In an old Duke Nukem game, when you get the drug pickup, you get max hp but your hp slowly goes back to what it originally was. That means if you were in a fight with low hp, you could take a hit of drugs and keep fighting till your hp starts getting back to low again then run off to buy food instead of using about 18 units of food ^^.
Oh yea to make it realistic, you should not be able to keep on eating. Oh heres an idea, make it like WoW. To eat you cannot move, you must stand still and to eat each unit of food it takes 5 seconds (1 unit of food regens 5 hp), regening 1 hp every second. So if you were on 10hp, you would have to eat 18 units of food (to get max health) which would take 90 seconds. However if you move while eating, you automatically cancel the eating.
This way it won't be like on dm servers where people run around fighting then quickly hide then type !heal when there a bit low. This way they would have to stand still which means they cannot be near anyone trying to kill them

We could have different affects for different drugs for example (forgive my misspelling of drug names):
Marajuana: Constant regen of up to (100 - originalhp). After you have gained (100 - originalhp), hp goes back to original value gradually. I say (100 - originalhp) intead of just untill you get to 100hp becuase otherwise if you were being attacked, that means you can constantly regen as long as the other player attacks you before you hit 100hp. If while a player is lose hp to get back to orignial but is attacked and gets under original hp, the negative regen stops.
example of Mara...
Player has 50 hp
Player smokes
Player begins to regen
Player regens up (100 - originalhp)
Player begins to lose hp gradually to get to original
Extesy: Instant hit of about 20 hp but after a while, gradually lose up to (20 + 5*1). If you take another pill while still regening, you will reduce up to (20 + 5*2). The basic formula is ([HP LOST BY NEGATIVE REGEN]=20 + 5*[AMOUNT OF PILLS TAKEN DURING REGEN]).
example of Ex...
Player has 50 hp
Player takes pill
Player gains 20hp (now 70hp)
Player begins to lose hp gradually lose up to (20 + 5*1) which gets him/her to 45hp
example of constant Ex...
Player has 10 hp
Player takes pill
Player gains 20hp (now 30hp)
Player takes pill
Player gains 20hp (now 50hp)
Player takes pill
Player gains 20hp (now 70hp)
Player takes pill
Player gains 20hp (now 90hp)
Player takes pill
Player gains 20hp (now 100hp)
Player begins to lose hp gradually lose up to (20 + 5*5 = 45) and as 10hp - 45hp is less than zero (-35hp), this means he/she will die due to negative regen if he does not get atleast 36hp from another source such as food/paramedic/pickup/etc.
The main points are below:
-Food regens gradually hp with no negative effect but must stand still to eat.
-Extesy gives instant hits of hp but makes you lose hp over time, losing more hp the more pills you take.
-Marajuana gives you regen but you can move or fight while regening (unlike food) but you grdually lose hp once positive regen is over.
I'll add this is too
-Taking Marajuana constantly just increases the rate of your positive and negative regen, it does not change to amount you gain/lose.
Oh i just though of another idea, ill go make a topic on it now, it's related to storing your food/drugs at places you own ^^.
Ok I would like to add something else. You should not be able to carry 1000 units of food as that would not be unrealistic, there should be a limit to what you can carry. The same goes for drugs (although you should be able to store more drugs).