# What counts as a disease?

Do any books contain a rules definition of what is and is not a disease.

Here are some examples of aliments I, the DM, would like to see if they match the definition if such a thing exists. I put a broad range of aliments here and included things like Kidney Failure to try to illustrate what I would like to compare to the definition.

Examples:

• Down Syndrome
• Diabetes
• Kidney Failure
• Malaria (Dormant or Active)
• Are you looking for a rules answer? None of these are statted up as diseases anywhere in D&D. (by my knowledge, anyway) – Erik May 6 at 16:38
• @Erik I am looking for the games definition of a disease to see if these conditions fit it. I gave a wide range of examples to see if they would fit that definition. I know one of the books in 3.5e had example diseases in it and was hoping 5e might have more information on this than 3.5e had. Sorry I am not as familiar with 5e and what may or may not exist. – Max Young May 6 at 16:43
• Nope, 5e does not do like 3.5e does (nor as AD&D 1e did) and give extended treatment to disaese in DMG chapter 8. Here are a few related answers to the Q&A "What spells could cure a stroke?" that you may find helpful: Ryan C. Thompson's answer and my answer. – KorvinStarmast May 6 at 16:56

Diseases are covered in the DMG under Chapter 8. Some samples diseases are provided, but those are just samples and examples of in-game diseases.

The things you list in your question are not in-game and do not have any rules around them, so it becomes up to the DM(you) to determine. But if a DM is wanting to draw in real-life medical issues into the game, then they should follow medical terminology. Searching real-world trustworthy sources will let you know if something is a disease, condition, or something else.

But, if it is a disease, then there is no reason you can't treat it like an in-game disease and have lesser restoration deal with it (or a paladin simply be immune to it.)

• Thank you, my search on D&D Beyond did not come back with this section because I searched Disease instead of Diseases, I was kind of expecting the search to be more fuzzy than it acted. These samples are very similar to what I remember from 3.5e so give me and idea of how to form a ruling myself. Unfortunate that they don't have a strict rules definition, since we are dealing with magical healing but it does leave the DM open to explore so probably for the better. – Max Young May 6 at 16:59
• Ok, comments be gone. @MaxYoung yeah, for you as DM to have some wiggle room is a good thing. :-) – KorvinStarmast May 6 at 17:04
• @MaxYoung Yeah, dndbeyond's search is...suboptimal. – NautArch May 6 at 17:06

Although D&D 5e does not provide a medical definition of a disease, from the examples presented it appears that the term is meant to encompass contagious illnesses. For instance, this site lists sight rot, cackle fever, and sewer plague. All of these can be contracted by proximity or contact, suggesting that they are caused by some contagious element, be it viral, cellular, prionic, magical, or whatever.

The terminology used in the description supports this:

A plague ravages the kingdom, setting the adventurers on a quest to find a cure. An adventurer emerges from an ancient tomb, unopened for centuries, and soon finds herself suffering from a wasting illness. A warlock offends some dark power and contracts a strange affliction that spreads whenever he casts spells.

A simple outbreak might amount to little more than a small drain on party resources, curable by a casting of lesser restoration. A more complicated outbreak can form the basis of one or more adventures as characters search for a cure, stop the spread of the disease, and deal with the consequences.

"Plague", "contract" and so forth. I would say that these are supposed to be infections. There's no mention of any medical condition that arises from genetics, diet, age, trauma, or other such stimuli.

Obviously, the DM is free to classify any other condition as a disease if they so desire. However, both some philosophical introspection and some consultation with players may be in order. The definition of a disease is controversial: Is disease a deviation from what the patient considers ideal, what society considers optimal, or from some abstract biological notion of correct functioning? Handled poorly, this is a matter that could even end up being hurtful to players. One should probably ensure that, whatever one's personal outlook, both DM and players agree on the definition and mechanics that will be used in-game.