So after discussing the idea with @cerulean mountain, I wanted to put together this list, and I want YOU 🫵 to contribute to this thread.
For context, alchemy in Ardenfall is going to be tiered. Just like how potions are tiered, the ingredients you use affect the tier, but also require a higher alchemy skill. The simple idea is that you can't craft potions that are beyond your skull level, but that's no fun, and this game lets you use weapons armor and slates without the proper skill so why not potions? To this end, the idea is that using ingredients beyond your skill level will make the intended potion... But they come with fun, but temporary side effects. This is a list of ideas from me personally.
Gills: You can breathe underwater... But you can't breathe on land.
Intoxication: All the downsides of being drunk without the charisma buff.
Deaf: Mutes all audio.
Astigmatism: Become nearsighted.
Throat rash: Periodically cough, canceling movement and animations.
C.I.P.: The health bar becomes invisible. Know no pain.
Bioluminescence: Become your own light source. Also you can't sneak.
Jitters: Picking locks and pockets becomes impossible.
Heat flash: Stamina doesn't recover.
Greed: You automatically pick up anything in storage containers. Cannot drop items.
Hangover: Dramatically increases the gama and bloom. Dark mode users will hate it.
Lead feet: Dramatically reduces jump height. Automatically sink in water. Sprinting consumes stamina.
Stone skin: Become immune to damage, but also become petrified.
I.B.S.: Slowly lose health over time. Also fart every time you're hit.
Caffeinated: Removes well rested effect. Cannot sleep for 24 hours.
Odor: Decreases your stealth skill and lowers your reputation with all factions significantly.
Delirium: Cannot see quest objectives or map markers.
That's all I can think of for now, but I want to know what ideas you have.