Plague & Peril: Surviving Disease in AD&D

Who knows, maybe that blood infection could kill you...

When you think of danger in Advanced Dungeons & Dragons, your mind probably jumps to dragons, traps, and sword-wielding enemies. But let’s talk about a threat that’s far more insidious: disease. It’s not flashy, it doesn’t roll initiative, but it’s one of the most immersive mechanics in AD&D, bringing a gritty realism to your campaigns that no fireball ever could.

AD&D’s disease and parasitic infestation rules aren’t just about rolling dice to see who gets sick. They’re about survival. They challenge your players to think about more than just combat—to consider the environment, their decisions, and even the consequences of ignoring basic hygiene. Filthy conditions, polluted water, improperly cooked meat—any of these could tip the scales, turning a simple journey into a life-or-death struggle.

How Disease Works in AD&D

Here’s the deal: every month—or week if things get especially grim—you roll to see if your characters have contracted a disease or picked up a parasite. The base chances might seem small (2-3%), but the modifiers can stack fast. Hot, humid climates? Add 2%. Filthy surroundings? Add another percent. Old age, marshlands, exposure to carriers—before you know it, your hardy adventurer is looking at a serious risk of falling ill.

And it’s not just about numbers on a table. AD&D’s disease rules encourage you as the Dungeon Master to think creatively. What’s the source of the illness? A tainted well in the heart of a besieged city? A parasitic infestation from swamp water? These details flesh out your world, turning what might feel like random mechanics into rich storytelling opportunities.

Why Disease Matters

Disease changes the game. It forces players to think differently, to prioritize more than just their combat stats. Sure, you’ve got a +2 sword, but is that going to save you when you’re too weak to lift it because you didn’t boil your water?

This mechanic adds layers to your campaign. It’s not just about rolling dice to survive; it’s about the ripple effects. A sick character slows down the party, uses up precious resources, and could even spark moral dilemmas. Do you leave your ailing companion behind to escape the dungeon, or do you risk the whole party to find a cure?

And let’s not forget the drama. Imagine the group finally escaping a deadly trap-filled ruin, only to realize the rogue’s persistent cough isn’t from the dust—it’s from the parasitic eggs they inhaled in the swamp two weeks ago. Now, the clock’s ticking, and the party has to find a healer—or a cure—before things get worse.

How to Use It Without Overwhelming Your Players

Balance is key here. You don’t want your game to turn into “Disease & Dice Rolls” where every session feels like a public health seminar. Use these rules sparingly but effectively. Make diseases rare but impactful, something that makes the world feel alive without bogging down the game.

Tie the afflictions into your narrative. Maybe the local town has been struck by a mysterious illness, and the party has to investigate its source. Or perhaps the disease is the result of a curse, a punishment for disturbing an ancient tomb. When used right, disease isn’t just a mechanic—it’s a plot hook, a challenge, and a storytelling tool all rolled into one.

Why You Should Embrace the Danger

At its core, AD&D is about more than just rolling high and killing monsters. It’s about immersion, about stepping into a world that feels real and unforgiving. Disease and parasites are part of that. They remind players that this isn’t just a game—it’s a world where every decision, every misstep, has consequences.

So the next time your players confidently stride into a swamp or decide to camp in a filthy, rat-infested alley, remind them that the greatest threats aren’t always the ones with teeth and claws. Sometimes, it’s what you can’t see that gets you.

Want to know more? Tune into my podcast episode “Plague & Peril: Surviving Disease in AD&D” for a deep dive into how these mechanics can transform your campaigns. And if you’ve got your own stories about using disease in your games, drop them in the comments—I’d love to hear how you’ve kept your players on their toes!

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