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In most fiction, [[NoPeriodsPeriod periods are rarely mentioned]]. SpeculativeFiction normally does likewise, but on the rare occasions that it does mention menstruation, the characters should tremble. Menstruation in SF holds great sway over supernatural powers.

SF periods serve as the trigger for every supernatural menace you can think of. Gruesome BodyHorror is the favorite, but a period can also serve as a source of great power (and [[WithGreatPowerComesGreatInsanity great insanity]]), a magnet for TheFairFolk, a gateway to a hell dimension, or even a semi-sentient RealityWarper. Periods also cause all sorts of supernatural powers, from PubertySuperpower, to [[UnequalRites attunement to magic]]. You're gonna need more than chocolate to sort this one out.

The Menstrual Menace is particularly popular as a MonsterOfTheAesop. Any monster evolving out of a girl's period will serve as an object lesson of how to deal with the [[{{Pun}} pain of puberty]]. If the moral is that GrowingUpSucks, the whole cast will be dead or insane by the end. At the more idealistic end of the SlidingScaleOfIdealismVersusCynicism, defeating the Menstrual Menace will be an {{Anvilicious}} moral about the importance of [[ItsAllJunk abandoning childish things]]. By virtue of them both running on a roughly monthly cycle, periods are also sometimes compared to [[OurWerebeastsAreDifferent lycanthropy]] or the latter is used as a [[StockMonsterSymbolism metaphor]] for the former.

Menstruation in SpeculativeFiction also causes mundane misery and angst, which tend to lead to stupid mistakes that create all of the previous supernatural problems.

The belief systems of some cultures have often incorporated a strong positive or negative supernatural significance to the phenomenon of menstruation.

This trope is for supernatural periods only; for trouble caused by mundane periods, see AllPeriodsArePMS. Compare WomensMysteries. See also HystericalWoman and AllWomenAreLustful, two beliefs brought on by this very trope. This can be paired with PsychosexualHorror.
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!!Examples:

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[[folder:Advertising]]
* One of the best male footballers in the world Ilhan Mansiz is challenging anyone to a football game. A confident young lady accepts the challenge despite being on her period. Ilhan tries to dribble past her but she quickly wins the ball, dribbles past him, and scores an incredible goal despite wearing her Evy Lady pad. She rubs her victory in and all the women cheer in the background. So much girl/period power: https://youtu.be/Au1xyaxCXeI?si=AdtN919iOjwqA38n
* Professional men's cyclists are having a race but all of a sudden a lady is seen cycling and talks about her Always pantyliner. Thanks to it's features and comfort she easily races past all the professional athletes. Men cannot believe it while she smiles and gives them a wink. Period power for sure: https://youtu.be/cBNYNTAE_qQ?si=NlhdZIbkDSzItjEc
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[[folder:Anime & Manga]]
* The third chapter of ''Manga/CellsAtWorkLady'' has PMS as the cause of the abnormalities that attack the cells that work in the female body.
* In ''Manga/{{Karin}}'', the eponymous character has a monthly release of blood... from her [[{{Nosebleed}} nose]] (unless, of course, she injects it into a human). The similarity to a menstrual cycle is frequently lampshaded, especially in the beginning.
* Referenced and Averted in ''Anime/NeonGenesisEvangelion'': When Asuka starts losing the ability to synchronize with her Evangelion, Misato offers the fact that Asuka is on her period as an explanation for why, but Ritsuko immediately denies that this could be the cause and states that sync ratios are not affected by physical changes.
* Tsukiko Sagi in ''Anime/ParanoiaAgent'' suffered one during middle school. [[spoiler:This made her drop Maromi's leash, accidentally letting her dog run to the street and get run over by a car. Combined with the stress of having to suffer her strict father's punishment, this ends up creating Lil' Slugger so she avoids punishment by saying it was him who killed her dog but not because she couldn't explain the sudden pain, given she had pestered her father to buy Maromi for her and she was raised to be very introverted.]]
* In Episode 4 of the first season of ''Literature/{{Slayers}}'', Lina Inverse has her powers of magic reduced by 99.9999999% for a few days due to her "Time of the Month", and this happens to ''all'' female magic wielders. It's never mentioned again. (The show turned out to have a larger female audience than expected, and the writers didn't want to offend them). This is also the one instance where [[TheDitz Gourry]] understood pretty much immediately the reason behind something being wrong with Lina. Amusingly, though, Gourry doesn't know what "that time of month" actually is, and only knows it's something that girls don't like talking about.
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[[folder:Comic Books]]
* Creator/GrantMorrison's ''ComicBook/DoomPatrol'' run has Dorothy Spinner, a mutant who creates {{imaginary friend}}s with her powers. Due to trauma, she acts like she's a little girl. A period is enough to bring back her horrible memories, and the Candlemaker -- a gruesome monster that only children and lunatics can see. Artist Richard Case also made sure to draw Dorothy with red shoes, a longtime symbol for menstruation and a woman's maturation.[[note]]Of course, they also tie her to [[Film/TheWizardOfOz another fictional Dorothy]].[[/note]] Rachel Pollack expanded on the plot point of Dorothy's powers becoming stronger during her menstrual cycle because her first period was badly traumatic. Nobody had bothered to explain to Dorothy what would be happening to her body when she finally reached puberty, and her period began while a group of boys were mercilessly bullying her. After Dorothy finally made it home, her mother belittled her over the incident and said to Dorothy's face that she should've aborted her. This horrible experience became linked to Dorothy's power because, a little afterwards, she tried to "kill" some of her imaginary friends because she thought she was too old for them.
* Back in the 1980s, there was a black-and-white comic called ''MS. PMS''. A woman is infected by an alien device that locks her into a permanent state of PMS -- frazzled hair, bad attitude, super-human strength. The aliens were present too, wearing their environmental armor called P.A.N.T.I.E. shields. This comic [[ShortRunners lasted about two issues]], [[QuirkyWork perhaps unsurprisingly]].
* Alan Moore's ''ComicBook/SwampThing'' story "The Curse" (volume 2, issue #40) draws parallels between menstruation and the traditional lunar-cycle-based activity of werewolves.
* In MediaNotes/TheDarkAgeOfComicBooks, there was an independent series, ''ComicBook/CrimsonPlague'', about a woman whose blood contains a virus capable of wiping out a planet in hours. Cut her, your whole world is dead -- and since she's female, leave her alone for a month, you're still dead...
* In ''ComicBook/{{Fables}}'', Frau Totenkinder first began to receive her magical powers after she had her first period ([[OlderThanTheyLook back in the Stone Age]]). It's mentioned that her shedding of blood fueled her powers; however, she soon finds that the blood of other children gives her even more power. (Her name ''is'' [[MeaningfulName Mrs. Dead Children]]...)
* In ''ComicBook/HexWives'', Danali's magical powers activate when she has her first period. Isadora gives her some pretty frank advice on dealing with menstruation.
* Played with in ''ComicBook/{{Runaways}}'':
** The first issue features Molly (around 12 years old) trying to get older female characters' attention to ask about changes in her body and unusual bleeding. [[NotNowKiddo They blow her off]], assuming that it's her first period, but it turns out to be a PsychicNosebleed associated with her [[PubertySuperpower mutant powers emerging]].
** Downplayed with Nico, who has to draw her own blood to call forth her magical staff. Menstruation counts, so she doesn't always have to self-harm. It doesn't have any other effect on her powers, though.
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[[folder:Fan Works]]
* There's a joke in ''VideoGame/TheKingOfFighters'' Fanon that the only time Leona transforms into her [[SuperpoweredEvilSide Riot]] [[MindControlEyes of Blood]] form is during that time of the month.
* PlayedForLaughs in ''FanFic/TheRWBYLoops''. Yang Xiao Long canonically has the ability to absorb power from damage and use it against her foes. In one particular loop, cramps count as hits; this makes her reckless enough that her sister and teammates hid behind various features of the landscape, whilst Nora complains about how lucky she is.
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[[folder:Films -- Live-Action]]
* Exaggerated by ''Film/Carrie1976'' as [[RealLifeWritesThePlot a side effect of being forced to cut the rain of stones]] on Carrie's house in the DistantPrologue. As a result, it seems that Carrie's telekinetic powers ''start'' when she gets her first period.
* ''Film/DogSoldiers''. The sole female character quips "It's that time of the month" [[spoiler:as she turns into a werewolf.]]
* During the superhero "[[TerribleIntervieweesMontage tryouts]]" in the movie ''Film/MysteryMen'', a woman calls herself [[https://youtu.be/QXFR1L_gOg8?t=99 the PMS Avenger]], sporting a red outfit.
-->'''PMS Avenger:''' P.M.S. Avenger. I only work 4 days a month. Is there a problem with that?
* In ''Film/ImGonnaGitYouSucka'', a henchman tries to kidnap the heroine, and she turns into a demon on him. He thinks she's possessed by the devil, but she says, "No! Cramps!"
* ''Film/GingerSnaps'' also makes the menstruation/werewolf connection.
* In ''Film/TheReaping'', a little girl pretty much brings about the end of the world by getting her period. [[spoiler:Or so it seems for a while.]]
* In the 1993 remake of ''Film/AttackOfThe50FootWoman'', a doctor speculates that Nancy's condition is caused by a hormonal imbalance. Her husband's response is "Congratulations, doctor. You've just discovered a new form of PMS."
* ''Film/TheDevilInside'' has a menstruated and possessed woman spewing her blood at the camera.
* ''Film/{{Roh}}'': At one point Along wakes in the middle of the night and walks to the entrance of the family's home, where we see blood trickling down her leg. Due to the family living in a time and place without sanitary pads or running water, the only way she can deal with the menses cleanly is by going out into the woods and bleeding onto the ground. This results in another frightening encounter with the ghost of Adik, after which a terrified Along hides among the trees — and when the hunter comes across her and brings her home, the blood smeared on her legs makes her mother Mak think the hunter assaulted her.
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[[folder:Literature]]
* In Suzy [=McKee=] Charnas' short story ''Boobs'', the narrator, when she reaches puberty, changes into a werewolf for several nights per month instead of having periods.
* In the book ''Cycler'' by Lauren [=McLaughlin=], every month before her period the main character, Jill, turns into a boy.
* In Piers Anthony's ''Literature/{{Xanth}}'' books, Chameleon changes according to her cycle. At one point in her cycle, she is beautiful but dumb, at the opposite point, she is ugly but very smart and clever.
* Inverted in the ''Literature/BlackJewels'' series, where witches lose much of their power while menstruating.
* Creator/JustineLarbalestier's ''Literature/Liar2009'' also connects menstrual cycles and [[spoiler: lycanthropy. There is an excellent scene in the book when the reader is certain that the parents are locking up their daughter for having her period until it is revealed in the second half of the book that she is a werewolf.]]
* The title character of Stephen King's ''Literature/{{Carrie}}'' theretofore mild telekinetic powers become much stronger after her first period starts.
* Characters in ''Literature/ASongOfIceAndFire'' repeatedly suggest this as an explanation for Brienne's fierce fighting style. Their tone of voice while doing so tends to vary between misogynist mockery (if she's busy or out of earshot) and outright pants-wetting terror (if she's not).
* Nearly every ''Literature/{{Discworld}}'' book in which Angua has a significant role includes a time-of-the-month gag, but in her case, it's about [[OurWerewolvesAreDifferent lycanthropy]].
* {{Discussed|Trope}} in ''Literature/TheTwistedOnes'': One (elderly male) scholar's writings attribute a girl's supernatural experience to her first period, which he calls "a highly dangerous time in the spiritual life of women". The women who read this excerpt think he's just projecting his own fear of menstruation on the rest of the world.
* ''Literature/TheLastHuman'': Sarya mentions that her first period was perfectly normal for her species. Unfortunately, she had been adopted by a [[ProudWarriorRace Widow]] and told she was an entirely different species because being human would get her hunted down and killed. The species she thought she was don't get periods; if they start bleeding like that, it means they're dying. Her mother found her hiding in the air vents, preparing for some sort of blaze of glory suicide attack so that she could "die like a Widow should," and was forced to tell her that she was human after all.

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[[folder:Live-Action TV]]
* Parodied in the second episode of ''Series/GarthMarenghisDarkplace''. The sole female character has a psychotic break, then goes on a telekinetic rampage that kills several people. In the end, all is forgiven because she couldn't help herself -- it was her inevitable female foolishness and hormones (as Thornton Reed puts it, "I think it's her time."). The point, of course, is that Marenghi is a sexist hack who thinks nothing of stealing the plot of ''Carrie'' and making it about how women's issues lead to death.
* ''Series/GenV'' Oh boy, if you thought your first period was bad, you’ve got nothing on Marie Moreau. She found out she could weaponize blood when she had her first period, and accidentally killed her parents with it when she freaked out in the bathroom.
* In a bit sketch on ''Series/TheYoungOnes'', a young woman is sent to hell and threatened with all sorts of horrific punishments by a (female) devil. Then their dialogue shifts, as the scene is revealed to be a pain-reliever commercial on TV. The young woman goes on about "that strange washed-out feeling you just can't explain", but the devil confides that she's talking about ''period'' pains. Er, so PMS is so agonizing that it's comparable to being ''tortured in hell''?
* Played for laughs in ''Series/TheITCrowd'', where Jen's very angry period sees her literally turn into some kind of hell-demon at some points. This results in the image of a red-and-white skinned woman in a business suit screaming things like [[https://www.youtube.com/watch?v=OgWhT9rDO2g "I CAN NEVER FIND A BLOODY PEN AROUND HERE!"]].
* In ''Series/BuffyTheVampireSlayer'' Willow tells her new (werewolf) boyfriend Oz "Yeah, okay, werewolf. But three days out of the month I'm not much fun to be around either." Which was a bit of a shock moment, considering how shy and soft-spoken Willow normally is.
* In the sketch comedy show, ''Touch Me, I'm Karen Taylor'', Karen invented the super-heroine Pre-Menstrual Girl, who is the alter ego of normally pleasant and cheerful office worker Penelope. When trouble arises her super-heroine power kicks in: she alters her body-clock and transforms into [[https://www.youtube.com/watch?v=PCVrqV9uFzQ Pre-Menstrual Girl]], a superheroine who saves peoples' lives, either by winning the villain's heart with her neurotic sobbing, or terrifying him into bludgeoned submission by screaming, being aggressive, and sniping.
* One episode of ''Series/Charmed1998'' had the sisters' periods lining up with each other ''and'' with a blue moon, which... somehow... turned them into werewolf-like creatures who attacked Whitelighters. They're unaware of the situation at first, but strangely consider it a perfectly logical reveal once they figure things out.
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[[folder:Myths & Religion]]
* In Myth/NorseMythology, [[DaddysLittleVillain Gjalp]] attempted to [[NauseaFuel drown Thor in a torrent of her menstrual blood]]. Though in later versions, it's not menstrual blood, but [[{{Squick}} urine]]. In both versions, however, Thor stops the torrent by throwing a rock at her and plugging up... well, yes.
* In Myth/CelticMythology, Maeve (or Medb, or whatever Walisic naming you deem correct) holds back her period until the Big Battle ends. And then it's flood time, too.
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[[folder:Video Games]]
* In ''VideoGame/{{Bloodborne}}'', Yharnam, the Pthumerian Queen weaponized her menstrual blood (which was influenced by the stillborn [[EldritchAbomination Great One]] [[FetusTerrible Mergo]] inside her body) as a sort of BloodMagic. Her descendants, the Cainhurst Vileblood carried the very same blood on the [[KatanasAreJustBetter Chikage]].
* An easily-missed background detail in ''VideoGame/BioShockInfinite'' -- as scientists were researching [[RealityWarper Elizabeth]] from childhood to adulthood, a chart keeping track of her energy level reached a massive spike at a point listed as "menarche". Immediately afterwards, the tower was fitted with [[PowerLimiter siphons to limit her power]], but very quickly after that, [[PubertySuperpower they naturally escalated back to critical levels]], to a point that the facility was deemed unsafe.
* In Episode 4 of ''[[VideoGame/TheWalkingDeadSeasonThree The Walking Dead: A New Frontier]]'', Clementine confides in Javi that she's started bleeding, and asks him why. Javi can choose to awkwardly give her TheTalk.
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[[folder:Webcomics]]
* In ''Webcomic/CursedPrincessClub'', [[spoiler: Princess Calpernia]]'s curse ultimately turns out to be related to this. Specifically: she [[spoiler: turns into a GiantSpider on her period.]]
--> [[spoiler:'''Princess Calpernia''']]: The [[spoiler: were-spider]] curse works by latching on to some monthly phase at the time it was activated. But... instead of a phase of the moon, it latched onto a different 'time of the month' that I was on that night... if you get what I mean. I-in other words... I turn into a [[spoiler: giant, ravenous, deadly spider]] once a month during my period.
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[[folder:Web Original]]
* In the ''Literature/WhateleyUniverse'', superpowered mage Fey has her first case of PMS in her first few weeks at SuperheroSchool Whateley Academy. This leads to thunderstorms, lightning bolts, and rain. In the dorm hallways. For bonus points, all the magical fun ''also'' triggers menstrual discharge in every other girl in the dorm. Including the ones who had just finished with this month's visitor.[[https://whateley.academy/index.php/story/fey-2-pms-and-other-problems]]
* Creator/{{Humon}} has her own Menstrual Monster, which she learned to tame with medical assistance. See '''[[http://humoncomics.com/communists-in-the-funhouse here]]'''
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[[folder:Western Animation]]
* Half-demon Callie in ''WesternAnimation/UglyAmericans'' undergoes "[[FunWithAcronyms Painful Mortal Shedding]]", a process in which a female demon periodically molts her toxic flesh. The agony can only be minimized by near-constant sex with her boyfriend/human sex slave Mark. In the background of another episode, a calendar in Mark's apartment has two weeks marked as "Callie's Period", so apparently that's a bit different for demons, as well.
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