Diseases

Arcane Blight

Source: Icewind Dale: Rime of the Frostmaiden p. 233

Any humanoid that spends 12 hours in the necropolis must succeed on a DC 15 Constitution saving throw or contract an arcane blight. This magical disease transforms the humanoid into a nothic, but only after the victim experiences hallucinations and feelings of isolation and paranoia. Other symptoms include clammy skin, hair loss, and myopia (nearsightedness).

A player character infected with the arcane blight gains the following flaw: "I don't trust anyone." This flaw, which supersedes any conflicting flaw, is fed by delusions that are difficult for the character to distinguish from reality. Common delusions include the belief that that allies are conspiring to steal the victim's riches or otherwise turn against the victim.

Whenever it finishes a long rest, an infected humanoid must repeat the saving throw. On a successful save, the DC for future saves against the arcane blight drops by dice: 1d6|avg|noform (1d6). If the saving throw DC drops to 0, the creature overcomes the arcane blight and becomes immune to the effect of further exposure. A creature that fails three of these saving throws transforms into a nothic under the DM's control. Only a wish spell or divine intervention can undo this transformation.

A greater restoration spell or similar magic ends the infection on the target, removing the flaw and all other symptoms, but this magic doesn't protect the target against further exposure.

Blinding Sickness

Source: Player's Handbook p. 227

Pain grips the creature's mind, and its eyes turn milky white. The creature has disadvantage on Wisdom checks and Wisdom saving throws and is blinded.

Blue Mist Fever

Source: Tomb of Annihilation p. 40

A magical mist creeps through the jungles of Chult. Contact with this thin, blue, odorless mist can infect giants and humanoids with blue mist fever. A dispel magic spell destroys the mist in a 20-foot square starting at a point chosen by the caster within the spell's range. An encounter with this mist typically covers dice: 1d6|avg|noform (1d6) such areas (400-2,400 square feet).

A giant or humanoid that comes into contact with the mist must succeed on a DC 13 Constitution saving throw or become infected with blue mist fever. An infected creature begins seeing vivid hallucinations of blue monkeys dice: 1d6|avg|noform (1d6) hours after failing the save, and the hallucinations last until the disease ends on the creature. A creature can repeat the saving throw every 24 hours, ending the effect on itself on a success.

Bluerot

Source: Ghosts of Saltmarsh p. 234

This disease targets humanoids. While afflicted with bluerot, a victim grows grotesque blue boils on their face and back. This disease is carried by undead (including the drowned ones in Tammeraut's Fate), and victims most often acquire it through wounds caused by infected creatures. The disease's boils manifest in dice: 1d4|avg|noform (1d4) hours, causing the victim's Constitution and Charisma scores to decrease by dice: 1d4|avg|noform (1d4) each, to a minimum of 3. This is quickly followed by a fever and tingling in the extremities. An infected creature is vulnerable to radiant damage and gains the ability to breathe underwater.

At the end of each long rest, an infected creature makes a DC 12 Constitution saving throw. On a success, the victim regains 1 point of Constitution and 1 point of Charisma lost to the disease. If the infected creature regains all the points lost to the disease, it is cured. Other effects that raise the victim's ability scores do not cure the disease. On a failed saving throw, the victim takes dice:4d8|text(18) (4d8) necrotic damage as the boils burst and spread. A creature reduced to 0 hit points by this damage cannot regain hit points until the disease is cured, though it can be stabilized as normal.

Cackle Fever

Source: Dungeon Master's Guide p. 257. Available in the SRD.

This disease targets humanoids, although gnomes are strangely immune. While in the grips of this disease, victims frequently succumb to fits of mad laughter, giving the disease its common name and its morbid nickname: "the shrieks."

Symptoms manifest dice: 1d4|avg|noform (1d4) hours after infection and include fever and disorientation. The infected creature gains one level of exhaustion that can't be removed until the disease is cured.

Any event that causes the infected creature great stress—including entering combat, taking damage, experiencing fear, or having a nightmare—forces the creature to make a DC 13 Constitution saving throw.

On a failed save, the creature takes dice:1d10|text(5) (1d10) psychic damage and becomes incapacitated with mad laughter for 1 minute. The creature can repeat the saving throw at the end of each of its turns, ending the mad laughter and the incapacitated condition on a success. Any humanoid creature that starts its turn within 10 feet of an infected creature in the throes of mad laughter must succeed on a DC 10 Constitution saving throw or also become infected with the disease. Once a creature succeeds on this save, it is immune to the mad laughter of that particular infected creature for 24 hours.

At the end of each long rest, an infected creature can make a DC 13 Constitution saving throw. On a successful save, the DC for this save and for the save to avoid an attack of mad laughter drops by dice: 1d6|avg|noform (1d6). When the saving throw DC drops to 0, the creature recovers from the disease. A creature that fails three of these saving throws gains a randomly determined form of Madness.

Filth Fever

Source: Player's Handbook p. 227

A raging fever sweeps through the creature's body. The creature has disadvantage on Strength checks, Strength saving throws, and attack rolls that use Strength.

Flesh Rot

Source: Player's Handbook p. 227

The creature's flesh decays. The creature has disadvantage on Charisma checks and vulnerability to all damage.

Frigid Woe

Source: Explorer's Guide to Wildemount p. 125

Frigid woe is a special disease developed by Aeor's mages that cannot be cured by conventional treatment or magic. The only way a creature infected with the disease can be cured is by finding and drinking the manufactured antidote, a milky liquid stored in gold vials found in Eiselcross's ruins. This disease was created to slow down the forces of the gods and get around the healing power of their clerics and angels.

The disease is transmitted by breathing in blue spores that Aeor's mages created long ago. When a creature comes into contact with these spores, it must succeed on a DC 11 Constitution saving throw or become infected with frigid woe. It takes dice: 1d4|avg|noform (1d4) days for the symptoms to manifest in an infected creature. These symptoms include fatigue, chills, and visible blue veins that appear on the creature's body. The infected creature's speed is reduced by 5 feet as long as it remains infected. Every 10 days after symptoms appear, an infected creature must succeed on a DC 11 Constitution saving throw, or its speed is reduced by another 5 feet. If a creature's speed is reduced to 0 as a result of this disease, the creature dies and its body turns into a statue made of ice.

A creature can drink the antidote as an action, ending all symptoms and effects of the disease instantly.

Ghoul Gut

Source: The Orrery of the Wanderer p. 111

Water polluted with ghoul parts carries ghoul gut. A creature drinking this tainted water must succeed on a DC 12 Constitution saving throw or contract the disease. Symptoms strike when a victim starts a long rest or next becomes excited, as during combat. A victim suffers severe cramps, and their bowels make sounds like two ghouls fighting. When the symptoms first strike, the victim takes dice:2d4|text(5) (2d4) necrotic damage. In addition, a diseased victim regains no hit points or Hit Dice from nonmagical sources, including resting or spending Hit Dice. A victim who finishes a long rest can attempt a DC 12 Constitution saving throw. On a successful save, the victim shakes off the disease. Failure deals the character another dice:2d4|text(5) (2d4) necrotic damage.

A character who succeeds on a DC 15 Wisdom (Medicine) check can also remove the disease from another creature. Doing so requires the character making the check to care for the sick individual during a long rest. The caregiver gains no benefit from that rest.

Grackle-Lung

Source: Out of the Abyss p. 54

The constant smog in Gracklstugh causes grackle-lung in living, breathing creatures, resulting in persistent, wracking coughs and the spewing of thick, black phlegm. Whenever a living, breathing creature finishes a long rest in Gracklstugh, it must make a DC 11 Constitution saving throw. On each failed save, the creature gains one level of exhaustion as its airways become increasingly clogged. A creature that reaches level 6 exhaustion dies, as normal.

A creature with one or more levels of exhaustion brought on by grackle-lung must succeed on a Constitution check to take the Dash action. If the check fails, the action cannot be attempted. If the creature attempts to cast a spell with a verbal component, it must succeed on a Constitution check or be unable to complete the spell, causing the spell to fail with no effect. The DC for each check is 10 + the creature's current exhaustion level.

If a creature's exhaustion level drops below 1, it no longer suffers the effects of grackle-lung and becomes immune to it for the next week. Duergar and derro are inured to grackle-lung, making Constitution checks against it with advantage. Any spell or effect that cures disease also cures grackle-lung, effectively removing all levels of exhaustion brought on by the affliction.

Mindfire

Source: Player's Handbook p. 227

The creature's mind becomes feverish. The creature has disadvantage on Intelligence checks and Intelligence saving throws, and the creature behaves as if under the effects of the confusion spell during combat.

Redface

Source: Ghosts of Saltmarsh p. 168

The effects of redface are identical to those of sight rot (see ""Diseases"" in chapter 8 of the "Dungeon Master's Guide"), but it's caused by pollutants in the air rather than contaminated drinking water, making it difficult to avoid.

Saprophytic Plague

Source: Candlekeep Mysteries p. 253

Xanthoria's research into lichdom and her creation of a living phylactery led to the emergence of the plague spreading across the Sword Coast. Any beast or humanoid that comes within 10 feet of a creature infected by the saprophytic plague must succeed on a DC 20 Constitution saving throw or become infected as well. On a successful save, a creature is immune to the plague for 24 hours, and any creature that is immune to disease succeeds on the save automatically.

After a failed save, a creature experiences the first symptoms—body aches, nausea, slurred speech, and uncontrollable drooling—dice: 1d4|avg|noform (1d4) hours later and gains 1 level of exhaustion. Every 24 hours thereafter, the creature automatically gains another level of exhaustion. Any creature killed by the saprophytic plague transforms into a lifeless magenta ooze.

A creature infected by the saprophytic plague for at least 24 hours behaves like a zombie and seems barely aware of its surroundings, as fungal growths sprout from its head, body, and limbs. It feels an overriding urge to be around groups of uninfected creatures so that it can spread the contagion. This is the time when infected humanoids begin speaking the word "Xanthoria" over and over, with no understanding of what the word means. This behavior is the result of a mycelial network of spores that forms a tenuous connection between Xanthoria and humanoids that become infected by the plague.

Foodstuffs that are exposed to the plague's spores decay or go sour within dice: 2d12|avg|noform (2d12) hours, leaving behind a lurid magenta mass of oozing fungi. Eating infected food requires a saving throw as above.

Any magic that cures a disease can rid a creature of the saprophytic plague. Casting purify food and drink destroys the infection in foodstuffs.

Seizure

Source: Player's Handbook p. 227

The creature is overcome with shaking. The creature has disadvantage on Dexterity checks, Dexterity saving throws, and attack rolls that use Dexterity.

Sewer Plague

Source: Dungeon Master's Guide p. 257. Available in the SRD.

Sewer plague is a generic term for a broad category of illnesses that incubate in sewers, refuse heaps, and stagnant swamps, and which are sometimes transmitted by creatures that dwell in those areas, such as rats and otyughs.

When a humanoid creature is bitten by a creature that carries the disease, or when it comes into contact with filth or offal contaminated by the disease, the creature must succeed on a DC 11 Constitution saving throw or become infected.

It takes dice: 1d4|avg|noform (1d4) days for sewer plague's symptoms to manifest in an infected creature. Symptoms include fatigue and cramps. The infected creature suffers one level of exhaustion, and it regains only half the normal number of hit points from spending Hit Dice and no hit points from finishing a long rest.

At the end of each long rest, an infected creature must make a DC 11 Constitution saving throw. On a failed save, the character gains one level of exhaustion.

On a successful save, the character's exhaustion level decreases by one level. If a successful saving throw reduces the infected creature's level of exhaustion below 1, the creature recovers from the disease.

Shivering Sickness

Source: Tomb of Annihilation p. 40

Insects native to the jungles and marshes of Chult carry this disease, shivering sickness. The easiest protection against it is a coating of insect-repelling salve on all exposed skin (for the cost of insect repellent, see "Buying a Special Item".

A giant or humanoid that takes damage from insect swarms or from giant centipedes, giant scorpions, or giant wasps is exposed to the disease at the end of the encounter. Those who haven't applied insect repellent since their previous long rest are exposed to the disease when they finish a long rest.

A giant or humanoid exposed to the disease must succeed on a DC 11 Constitution saving throw or become infected. A creature with natural armor has advantage on the saving throw. It takes dice: 2d6|avg|noform (2d6) hours for symptoms to manifest in an infected creature. Symptoms include blurred vision, disorientation, and a sudden drop in body temperature that causes uncontrollable shivering and chattering of the teeth.

Once symptoms begin, the infected creature regains only half the normal number of hit points from spending Hit Dice and no hit points from a long rest. The infected creature also has disadvantage on ability checks and attack rolls. At the end of a long rest, an infected creature repeats the saving throw, shaking off the disease on a successful save.

Sight Rot

Source: Dungeon Master's Guide p. 257. Available in the SRD.

This painful infection causes bleeding from the eyes and eventually blinds the victim.

A beast or humanoid that drinks water tainted by sight rot must succeed on a DC 15 Constitution saving throw or become infected. One day after infection, the creature's vision starts to become blurry. The creature takes a -1 penalty to attack rolls and ability checks that rely on sight. At the end of each long rest after the symptoms appear, the penalty worsens by 1. When it reaches -5, the victim is blinded until its sight is restored by magic such as lesser restoration or heal.

Sight rot can be cured using a rare flower called Eyebright, which grows in some swamps. Given an hour, a character who has proficiency with an herbalism kit can turn the flower into one dose of ointment. Applied to the eyes before a long rest, one dose of it prevents the disease from worsening after that rest. After three doses, the ointment cures the disease entirely.

Slimy Doom

Source: Player's Handbook p. 227

The creature begins to bleed uncontrollably. The creature has disadvantage on Constitution checks and Constitution saving throws. In addition, whenever the creature takes damage, it is stunned until the end of its next turn.

Spider Eggs

Source: Waterdeep: Dungeon of the Mad Mage p. 47

If the party is defeated, stabilized characters awaken after dice: 1d4|avg|noform (1d4) hours to find themselves cocooned in sticky webs and suspended 10 feet off the floor, with spider eggs implanted in their bodies. A cocooned character is restrained and can use its action to try to escape by making a successful DC 15 Strength check.

Spider eggs implanted in a host hatch in dice: 2d12|avg|noform (2d12) hours, killing the host as the baby spiders chew their way out. This infestation functions like a disease. A lesser restoration spell or similar magic cast upon the host kills the spider eggs, ending the threat.

Super-Tetanus

Source: Tales from the Yawning Portal p. 104

A creature that contracts the disease of super-tetanus is wracked with pain as its heart races and its muscles spasm hard enough to break its bones. The creature takes dice:2d10|text(11) (2d10) damage at the start of each of its turns. If a victim is not cured by other means, it can repeat the saving throw at the end of every minute after becoming exposed, ending the effect on itself with a successful save.

The Gnawing Plague

Source: Van Richten's Guide to Ravenloft p. 153

The Gnawing Plague, also known as "the Gnaws," is known in every corner of Richemulot.

Transmission

The Gnaws is spread when a creature is bitten by a rat, giant rat, swarm of rats, or wererat that carries the disease, or by coming into physical contact with an infected creature.

Infection

Creatures exposed to the disease must succeed on a DC 10 Constitution saving throw or become infected. The DC of this saving throw can increase depending on the severity of the plague's spread (see ""Cycle of the Plague"" below).

Symptoms

It takes dice: 1d2|avg|noform (1d2) days for the Gnawing Plague's symptoms to manifest in an infected creature. The infected creature then gains 1 level of exhaustion, regains only half the normal number of hit points from spending Hit Dice, and regains no hit points from finishing a long rest.

The plague's symptoms include buboes, fatigue, splotchy rashes, sweats, and shaking, particularly facial tremors. Locals liken these twitches to the sniffing of rats. Sufferers often have scraps of leather placed in their mouths to prevent their teeth from clattering, though they inevitably gnaw through these scraps.

Recovery

At the end of each long rest, an infected creature must make a DC 10 Constitution saving throw. On a failed save, the creature gains 1 level of exhaustion. On a successful save, the creature's exhaustion level decreases by 1. If a successful saving throw reduces the infected creature's level of exhaustion below 1, the creature recovers from the disease.

Immunity

All forms of rats and wererats are immune to the Gnawing Plague.

Throat Leeches

Source: Tomb of Annihilation p. 40

Minuscule parasites known as throat leeches infect the water in Chult's forests, swamps, and rivers. Any giant or humanoid that swallows tainted water must succeed on a DC 12 Constitution saving throw or be infested with throat leeches. Immediate symptoms include throat inflammation and shortness of breath. After dice: 1d6|avg|noform (1d6) hours, the infected character gains 1 level of exhaustion that can't be removed (except as described below) until the disease is cured. At the end of each long rest, the infected creature must repeat the saving throw. On a failed save, the creature's exhaustion increases by 1 level; on a successful save, the creature's exhaustion decreases by 1 level. If a successful saving throw reduces the infected creature's level of exhaustion below 1, the creature recovers from the disease.

Explorers can avoid contracting throat leeches by drinking only rainwater or water that's been boiled or magically purified.