Sickness is a terminal status affliction that, if untreated, will cause instadeath after a few turns. The main causes are eating too old corpses, special attacks, and cursed unicorn horns. The main remedies are applying a non-cursed unicorn horn, casting cure sickness, and quaffing certain potions.
The game uses "deathly sick" to specifically herald this condition, whereas there are many other cases where you simply "feel sick".
Contrary to its name, potion of sickness does not cause sickness.
Types of sickness
There are two distinct types of sickness, indicated separately on the status line. You can also suffer both conditions simultaneously. The effects and remedies are identical, except that only food poisoning can be cured by vomiting.
Food poisoning is completely preventable in vanilla NetHack if you don't eat old corpses. A corpse is too old to eat after 6 × (9 + 1d20) turns, where 6 is replaced with 8 if blessed and 4 if cursed. Corpses left by undead except wraith are always pre-aged by 100 turns; eaten immediately, they have 40% chance of causing food poisoning. Old corpses can be rendered safe to eat by tinning them. Lichen and lizard corpses never rot and may be safely eaten regardless of age.
The first time you contract the illness, a turns-to-live timer is started, set to between 20 and (19+Con). Each additional illness attack while you are
Ill divides the remaining turns-to-live by roughly 3.
Sickness can be easily cured with any of the following:
- applying a non-cursed unicorn horn
- praying to your god
- quaffing a non-cursed potion of extra healing or full healing, a blessed potion of healing, or (unless chaotic) a potion of holy water
- casting a spell of cure sickness
- eating a non-cursed eucalyptus leaf
- invoking the Staff of Aesculapius
The full list of less common remedies also includes:
- vomiting from eating tripe or a rotten egg. This cures food poisoning only, not illness. Quite unreliable, but it's there.
- polymorphing into a new version of yourself or a sickness-resistant monster (ghoul or some fungi). (A new version includes if you "fail" to change form, but get your attributes adjusted.)
- getting healed by a nurse's attack.
- sitting on a throne (1⁄13 chance).
The only sure-fire cures are the potions, prayer if safe, the spell at 0% failure rate, and polyself. A unicorn horn is good enough if you weren't made sick multiple times.
Importantly, poison resistance is not a remedy; if you become food poisoned and rely on this you will die.
- Ulch - that <food type> was tainted!
- The corpse you are eating is old enough to cause food poisoning.
- You feel deathly sick.
- You have contracted sickness and will soon die if untreated.
- It doesn't seem at all sickening, though...
- You would have contracted sickness but are resistant.
- You feel even worse.
- You feel much worse.
- You have worsened your sickness, further shortening your time to live ("much" if reduced by at least half).
- You feel somewhat better.
- Vomiting cured your food poisoning, but not illness. This doubles your time to live.
- You are no longer ill.
- The cure sickness spell is curing your sickness (even if it was food poisoning).
- What a relief!
- You have fully cured your sickness.
Enlightenment may reveal any of the following, which are self-explanatory:
- You are sick from food poisoning.
- You are sick from illness.
- You are immune to sickness.
Other uses of "sick"
- You feel sick.
- You ate an old-ish corpse or engulfed an undead monster, and lost 1d8 hit points.
- You feel very sick.
- You quaffed a potion of sickness that reduced your constitution. Replaces "You feel sick" if you are suffering sickness.
In SLASH'EM rot worms have an illness-inducing attack. You may also get food poisoning from swallowing a pill, and you can cure food poisoning by sitting on a toilet. The Necromancer and the Undead Slayer roles start the game with innate sickness resistance.
Keep in mind that here unicorn horns need to be enchanted in order to be reliable.
- polyself.c in NetHack 3.6.0, line 77
- you.h in NetHack 3.4.3, line 268: lists the two independent types of SICK: SICK_VOMITABLE an SICK_NONVOMITABLE.
- eat.c in NetHack 3.4.3, line 1270
- eat.c in NetHack 3.4.3, line 1253
- mhitu.c, line 773, apply.c, line 1458
- apply.c in NetHack 3.4.3, line 1541
- eat.c in NetHack 3.4.3, line 1725
- artifact.c in NetHack 3.4.3, line 1219
- polyself.c in NetHack 3.4.3, line 190
- polyself.c in NetHack 3.4.3, line 1411
- mhitu.c in NetHack 3.4.3, line 1407
- sit.c in NetHack 3.4.3, line 188
- potion.c in NetHack 3.4.3, line 126
- eat.c in NetHack 3.4.3, line 1300
- uhitm.c in NetHack 3.4.3, line 2078
- sit.c in NetHack 3.4.3, line 401
- potion.c in NetHack 3.4.3, line 675
- timeout.c in NetHack 3.4.3, line 47