Back in the early- to mid-2000s, I was heavily addicted to the computer RPG The Elder Scrolls: Morrowind. Last week, I dug out my old CDs and started the infuriating process of trying to install the game and get it to work properly on a laptop with Windows 7. But that's not really the point of this post.
One of my favorite parts of the game is the alchemy system, which allows your character to brew potions from a wide variety of ingredients found in the game world. In brief, each ingredient has up to four alchemical qualities - healing, levitation, restoring magic, fortifying attributes, etc. When you combine any two ingredients to brew a potion, the effects they have in common are the ones expressed in the potion's effects. Not all ingredient qualities are desirable, and typically an ingredient has both positive and negative qualities. Combine two ingredients that both happen to have the damage health quality, for instance, and the resulting potion will cause some harm when used. It's theoretically possible to produce useful potions that have undesirable side effects, if you use ingredients that match in two or more qualities. Unfortunately the game did a deplorable job of implementing that aspect, since very few ingredients were assigned the same positive and negative effects, so it's pretty easy to avoid any combination that produced side effects, but I digress.
Now, at last, to my point: Might it be more interesting to have potions in D&D that have unfortunate side effects? This would be especially appropriate for cheaper preparations. Someone on another blog (I can't recall which, so feel free to post links in the comments) suggested that the healing potions given to PCs as a reward for a minor good deed should be some sort of home remedy that causes a drunken stupor for a while.
I like this idea tremendously. Firstly, because it offers a way to give characters some resources without greatly cheapening the magic items they acquire through the blood, sweat, and tears of adventuring. Those are supposed to be fairly rare, made only by fairly high-level magic-users. It's entirely plausible that the local apothecary or hedge-wizard can whip up healing draughts, though, and this way such things can be available to the party without being the equal of full-blown healing potions. Secondly, because it offers an interesting choice: Do you drink the potion in the middle of a dangerous situation to restore your hit points at the expense of some of your combat efficiency, or do you try to tough it out and chug it during a rest break, when being a little tipsy isn't such a hindrance?
Effects other than drunkenness are possible. Minor hp damage, dulling or loss of one or more senses, loss of voice, weakness, loss of equilibrium, numbness, sluggishness, sleep or drowsiness, vertigo, aphasia, body changes/partial polymorph, hallucinations, euphoria, despondency, weakness to cold, heat, poison, or disease, paralyzation, heightened sensitivity to light or pain, amnesia, and others might be appropriate.
This looks like something for which a random table would be useful...perhaps side effects in rows, and severity, ranging from pretty bad to non-existant, in columns. You could roll randomly for potions placed in treasure troves, and for those brewed by a particular alchemist or apothecary. In the latter case, all the potions of a particular type made by that person will probably use the same recipe, and so have the same side effects. Potion recipes with less intense or less bothersome side effects might be highly sought-after both by PC magic-users and by NPC potion-brewers. High quality recipes would naturally cost more to make, both in ingredients and time, and maybe require a higher level magic-user or alchemist as well.
I think I'll go work up that random table now. If it turns out to be something useful and interesting, I'll post it soon.