The following are diseases that a character might contract in a game of Fifth Edition Fallout.

Unless otherwise noted, a disease's progress can be halted using antibiotics (see Chems).

Fungal Spores

Contact with the entomopathogenic fungus Beauveria mordicana can result in a living creature becoming a Spore Carrier. The fungus spreads via airborne spores, which enter the victim via inhalation or consumption of contaminated food. When exposed, a character must make a Constitution saving throw, which is DC 10 unless the victim is exposed by a Spore Carrier's spore explosion feature, in which case the DC is determined by the feature.

Fungal spores consume the carrier from within over the course of a number of days equal to 10 + twice the carrier's Constitution modifier. The first symptoms appear after 1d3 days have passed. The carrier begins to experience pain and discomfort, and suffers disadvantage on Strength- and Dexterity-based ability checks and saving throws. Each interval of 1d3 days following the manifestation of the first symptoms, the carrier suffers a level of exhaustion. Should the carrier die from their exhaustion levels, they become a Spore Carrier.


A character can contract this disease by eating suspect food or drinking contaminated water. The character must make a DC 11 Constitution saving throw or become a carrier for parasites.

While carrying parasites, a character must make regular toilet stops. Apart from being exceptionally unpleasant, this reduces their effective travel pace per hour by 1 mile and per day by 8 miles. Furthermore, the carrier must consume two meals to gain the benefits of one meal, and two drinks to gain the benefits of one drink (see Sustenance).


A character can contract this disease when bitten by a carrier of the disease, or when they come into contact with infectious material from such a creature and take no steps to avoid the contamination getting into their eyes, nose, mouth, or a wound. The character must make a DC 13 Constitution saving throw or become a carrier themselves.

The site of the bite prickles or itches until healed. Other symptoms of the disease manifest within 6d4 days, and initially include anxiety, confusion, and agitation. During this period, the carrier suffers disadvantage on Wisdom- and Charisma-based ability checks and saving throws.

After another 1d4 days, the carrier experiences more serious symptoms including insomnia, delirium, and hallucinations. As well as the previous symptoms, the carrier gains one level of exhaustion when the disease moves into this secondary stage and a further level of exhaustion every 24 hours thereafter.

During the secondary stage, the rabid template is applied to the carrier. In addition, once per short rest the GM can require the carrier to make a DC 13 Wisdom saving throw. On a failed save, the carrier becomes confused. It can’t take reactions and must roll a d12 at the start of each of its turns to determine its behaviour for that turn.

1. The carrier uses all its movement to move in a random direction. To determine the direction, roll a d8 and assign a direction to each die face. The victim doesn’t take an action this turn.
2. As 1, except the carrier is also Frightened of the nearest creature (if multiple creatures are equidistant, the carrier becomes Frightened by all of them) and the direction of its movement must be away from them by the most direct route possible.
3-6. The carrier doesn’t move or take actions this turn.
7-8. The carrier is dazed until the beginning of its next turn. While dazed, it has disadvantage on attack rolls and ability checks.
9-10. The carrier uses its action to make an attack against a randomly determined creature within its reach using a weapon in its hands or accessible during this turn. If there is no creature within reach/range of its ranged weapon, the carrier does nothing this turn.
11-12. The carrier can act and move normally.

At the end of each of its turns, the carrier can repeat its Wisdom saving throw. On a successful saving throw, the carrier is not confused and cannot be affected again until after its next short rest.

Vault 81 Mole Rat Disease

This disease was engineered in experiments within Vault 81's hidden laboratories. Although it was believed that all the mole rat carriers were eliminated by the Sole Survivor, it is possible some survived and escaped out into the wasteland.

A character can contract this disease when bitten by an infected mole rat. The character must make a DC 13 Constitution saving throw or contract the disease. Once a character makes their save, they are at no risk from contracting the disease from the same mole rat until 24 hours have passed.

Mole Rat disease manifests as a loss of vital energy, and its symptoms appear quickly, first manifesting on completion of the carrier's next long rest, or after 24 hours have passed if the carrier fails to take a long rest during that time. The carrier's maximum hit points are permanently reduced by an amount equal to their character level (increasing as they themselves level) until the disease is cured.

Antibiotics cannot cure mole rat disease. The only known cure for the disease was created by Curie, and she was only able to manufacture one dose. However, the very existence of that cure implies it might be possible to reproduce it. Curing the mole rat disease carried by one or more characters (or NPCs) could be the subject of an adventure.

Waste Plague

Waste Plague is a generic term for a broad category of illnesses caused through exposure to waste products and filthy creatures such as rad-rats. A character can contract this diseases when bitten by a carrier of the disease, or when they come into contact with rotten organic material or bodily effluence.

The character must succeed on a DC 11 Constitution saving throw or become infected.

It takes 1d4 days for the waste plague’s symptoms to manifest in an infected creature, after which the infected creature suffers one levels 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. The symptoms manifest physically as severe cramps and fatigue.

At the end of each long rest, the carrier repeats its 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. When a successful saving throw reduces the carrier’s level of exhaustion below 1, the character recovers from the disease.

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