Pancreatitis
Common
Common Causes: High cholesterol or heavy alcohol consumption.
Effect: You lose control of the part of your body that holds in farts, meaning you are constantly releasing a silent yet sweet smell. Since everybody can easily notice it, all stealth rolls you make decrease by 1.
The Yellow Plague
Common
Common Causes: Skin to skin contact, especially in crowded areas
Effect: Pus and bile oozes out of your pores, giving chest pain and general ill feeling. You will gain exhaustion at every dawn, long rests no longer get rid of them.
Warning: If you get to 12 levels of exhaustion before you treat the disease, you will instantly die.
Devil Rot
Uncommon
Common Causes: Bacteria carrying remnants of devil and demon bacteria getting into your nose. You can flavor it to something more realistic, somewhat based on staph infections.
Effect: Your skin burns within your body, causing a slight red tint and immense irritation, you can almost hear a sizzle. You gain a resistance to non-magical fire damage and you deal a point of heat damage to anyone you’re in physical contact with for more than a minute. However, you take an extra point of damage from all sources of damage.
Warning: If left untreated, the devil bacteria can eventually infect and kill vital organs like the heart or the lungs.
Glaucoma
Uncommon
Common Causes: Damage to the eye and diabetes from eye pressure. Age can make it easier to get.
Effect: Your life of blindness has begun, starting at your peripheral vision. Once per day when something out of your peripheral vision catches you by surprise, roll a DC 11 fortitude saving throw. Upon a failure, you are blinded for an hour.
WARNING: If left untreated, this disease can permanently make your character blind.
Cholera
Rare
Common Causes: Bacteria from heavy forest pollen getting into your nasal passages.
Effect: Your urine is neon yellow and you get dehydrated twice as usual. Not fulfilling the drink requirement of a long rest leads to two exhaustion instead of one.
Warning: If you gain 6 levels of exhaustion while having Cholera, you will die.
Tetanus
Rare
Common Causes: Taking in bacterial spores from soil and animal feces.
Effect: The muscles in your body periodically lock up, giving you disadvantage on all dexterity rolls.
Warning: If not properly treated within 4 days, the body will experience complete paralysis, putting you permanently into the paralyzed condition.
The Turquoise Death
Rare
Common Causes: High cholesterol or heavy alcohol consumption.
Effect: The first few days of being infected bring heart palpitations. While infected with this disease, you can no longer remove levels of exhaustion through long rests and your death’s door ratio becomes 30/70 (meaning the DM only needs to roll a 30 or above to kill your character)
Warning: Even after treatment, the disease remains infectious for about a week before it’s completely out of your system. Be wary of those around you.
Leprosy
Rare
Common Causes: Close and consistent contact with someone that has leprosy.
Effect: The nerves that process pain have begun to deteriorate, alongside your skin slightly dying and graying. You can’t heal outside of magic, short rests, and long rests. However you no longer feel the damage you take and grievous wounds won’t affect you. You obviously still suffer from critical wounds.