In fiction, illnesses always strike when it's most plot convenient, resulting in drama or Character Development.
For example, one of two refugees may be prevented from going on. Or a man may endure the elements for just a few hours for a woman and suddenly he's got a fever so bad he collapses. The obvious solution is Intimate Healing, because it always happens at night and hospitals are just too inconvenient or far away.
- In the Ah! My Goddess
- OAV, after Keiichi brings an unconscious Belldandy to the abandoned temple, he collapses from a fever and wakes up with his head in her lap.
- In the television series, while trying to create an antidote for the breasts Keiichi sprouted (courtesy of pudding made by Skuld), an explosion occurs, and Belldandy grows ill from inhaling the fumes. Keiichi spends the rest of the episode trying to take care of her.
- In Ai Yori Aoshi, Kaoru walks through the rain to get Aoi, who's just gotten lost for the second time on the Tokyo train system. After they get back to his apartment, he collapses from a fever and Aoi has to save him with some very Intimate Healing.
- In the Android/Cell Saga of Dragon Ball Z, Goku winds up contracting a heart disease that leaves him out of the action for roughly half the saga.
- In Future Trunk's timeline Goku actually died to the virus and without him the other Z-Fighters, excluding Gohan, ended up dying to the Androids leading them to wreaking havoc on the world basically unopposed.
- Toei's Yu-Gi-Oh! (first anime series) had Yugi get a cold in episode 15, which threw him off his dueling game and helped Risa exploit him for her own gain.
- Verity in The Transformers: Sins of the Wreckers is suffering from some sort of illness that gives her intense stomach pains, coughing fits, and leaves her much less physically capable than usual. Disturbingly, it seems to flare up every time a Transformer comes near.
- Spider-Man tended to get sick whenever he needed to struggle against lesser villains or lose outright. A famous example is in The Night Gwen Stacy Died, where he suffers from a cold for the first half, partially leading to Gwen's death, but it goes away in the second issue.
- Knightfall: Batman comes down with a serious cold due to his lack of self care after Superman's death. Bane ends up using this time to launch his attack.
- In Deewaar, Sumitra falls ill, forcing her son Vijay to decide whether to visit her and get arrested or turn his back on her. When he decides to do neither, she quickly gets well.
- In Moulin Rouge!, Satine's illness finally kills her at the worst possible time, just as she and Christian reunite during the climax.
- In Harry Potter, the Weasley twins invoke this by developing a range of sweets that make one ill and test them on fellow students in Order of the Phoenix. Hermione is unamused and shuts them down. Well, at least she manages to stop them from trying it on first-year students by threatening to write their mother. She can't really do anything about it when they test the candies on themselves and willing test subjects who are of age, and she can't stop the students from buying and using the sweets once they're perfected. Given that they're mostly used as a mode of rebellion against Umbridge, it's not that surprising she isn't doing more to stop it.
- Skellig: Had the baby never been sick, Michael likely wouldn't have felt so alienated from his family and therefore wouldn't have gone exploring by himself in dangerous places like the garage. Or he might've been enlisted by his parents to help more around the house or with the baby, in which case he just wouldn't have had the free time and might not have ever discovered Skellig.
- In Everworld, David gets sick when he has to separate from the rest of the team in the fifth book. The fact that he's so feverish means that there's a real chance that he won't be able to fulfill his mission in time.
- Luigi's Mansion: Dark Moon: In the ScareScraper mode of the game, there is a curse status effect that reverses your controls and can only be cured by using another player's Dark-Light. It comes complete with coughing from the player and is contagious, too.
- In Danganronpa, Kaito gets sick with a mysterious illness that makes him cough up blood. He later infects Kokichi as well. Kaito dies of his illness just before he can be executed.
- A couple in Melody:
- Melody gets sick right after Amy tells the protagonist to check in on her as Amy herself would do from time.
- Becca’s absence throughout much of Week 7 is explained away by her being sick in bed. She's then available to answer her door when Bethany shows up unannounced.
- Invoked in The Adventures of Jimmy Neutron, Boy Genius, when Jimmy invents a "sick patch" that make the wearer sick when applied, which the kids then use to stay home from school.
- The Fairly OddParents!: In one of the Oh Yeah! Cartoons shorts, Cosmo and Wanda get the fairy flu, which causes them to lose control of their magic. This illness is never mentioned again until Season 10, in "One Flu over the Crocker Nest."
- Star vs. the Forces of Evil: In "Star On Wheels", Glossaryck spends the first half of the episode not contributing at all to save Star from the runaway bike, even though his magic would have solved the problem immediately. The moment Glossaryck does decide to help, he gets sick from some food he had eaten earlier and becomes incapacitated.