, ,

wax-sculpture-black-deathThe characters in our Parsantium campaign recently came into contact with a disease bearing agent and I realised that I had addressed this issue many times before for many different game systems.

D&D 5e is a bit quiet on this topic and that’s OK: I’m happy with a more world-designer-friendly approach. Searching the interweb I found several useful ideas. And as a result here are my modernised house rules for dealing with disease.

CONTRACTING a (mundane non-magical) DISEASE

A character can be exposed to disease in many ways. Giant rats are consistently carrying one disease or another, and some areas such as swamps and some old ruins are plague spots. During wars, long sieges provide breeding grounds for disease.

When exposed to a source of disease (specify the generalised type ahead of time), the character must make a CON save against the DC of the disease (all the normal rules of thumb for deciding DCs can be applied here: 10 for weak, 20 for pretty bloody serious). All normal penalties and bonuses can be applied to this roll.

If this roll is failed the character has contracted the disease. The incubation period of the disease is d6 days (make a note of this period – for example 3 days). At the end of this period the character suffers 1 level of Exhaustion.

Every ‘period’ (for example, the 3 days found in the initial contraction) thereafter he must make a new CON save using the same DC as the initial contracting level. If successful the disease does not progress. If failed the character suffers an additional level of exhaustion. If the save is failed with a critical (1), the specific disease also reduces the relevant characteristic by one point, with all the attendant knock on effects.


Level Effect
1 Disadvantage on Ability checks
2 Speed halved
3 Disadvantage on Attack rolls and saving rolls
4 Hit point maximum halved
5 Speed reduced to 0
6 Death


Use these as both general descriptors of the effects of the disease and also specific pointers as to the deleterious effects on characteristics if critical failures are rolled during progression/recovery.

  • Wasting Disease – steals Strength
  • Brain fever – reduces Intelligence
  • Soul Waste – saps Wisdom
  • Creeping Chills – saps Constitution
  • The Shakes – steals Dexterity
  • The Pox – ravages Charisma


To reduce the levels of exhaustion a character must first stabilise: save and therefore not progress, and then save again the next test. On this second test the Exhaustion is reduced by a level. The next level must be saved against twice: once to stabilise and then to reduce.

If a character makes his save when on level 1 exhaustion he has reduced this to 0 and has therefore recovered naturally from the disease.


  • A character fails his saving roll against Soul Waste
  • The DM rolls d6 and discovers the incubation period is 3 days
  • Three days later the character makes a CON save roll and fails. He gains 1 level of Exhaustion, suffering a Disadvantage on all Ability checks and notices that his judgement seems to be impaired (role playing opportunity)
  • Three days later he rolls again, failing with a Critical (1). His Exhaustion is now level 2. His speed is now halved and his Wisdom is reduced by 1
  • Three days later he rolls but this time he saves. The Soul Waste does not progress but he is still suffering Disadvantage on Ability check, still suffering half speed and is still at -1 Wisdom
  • Three days later he rolls and saves again. His Exhaustion is reduced to level 1. He can now move at full speed but still has a Disadvantage to Ability checks and is still -1 Wisdom
  • Three days later he rolls again and saves. The disease does not progress.
  • Three days later he rolls again and saves again. His Exhaustion level is reduced to 0 and his Wisdom returns: he has spontaneously recovered! The natural course of the disease was 18 days.