In A Brother's Price, a drug commonly used on male prostitutes seems to act like a love potion; while its exact effects are unclear, the implied "last longer" effect suggests that it's a kind of powerful aphrodisiac. A woman having one in her possession is viewed as intending to rape a man.
John Collier's short story "The Chaser", which inspired an episode of The Twilight Zone, involves a Dogged Nice Guy who buys a love potion for just one dollar to win over his unrequited love interest. The seller keeps talking about a $1000 "glove cleaner", hinting that although he does not know if it cleans gloves, it does work as a Perfect Poison. He also indicates that using the love potion will turn his love interest into a Clingy Jealous Girl. Significantly more creepy than the episode based on it, the entire story is told as the conversation between the buyer and the seller, strongly implying that the young man will at some point be back for the glove cleaner as the eponymous "chaser" to the love potion.
Implied, and played very darkly, in Chronicles of the Kencyrath. By the time we meet them, Torisen is avoiding Kallystine and waiting for their time-limited marriage contract to expire. From how Torisen mentions her, it's implied that a year or two back, their relationship was a Destructive Romance. It was an arranged marriage, and Kallystine was trying her hardest to seduce Torisen for political reasons. Torisen knew this perfectly well, and he came to resent and hate her... but it seems she did manage to seduce him for short periods of time, anyway. It's implied that she was probably using magic to do this.
His former consort had been adept at intoxicating the senses, but with an after-taste that had made him both loathe and mistrust his own passion. One of the Highborn subsequently thrown at him, a ridiculously young Ardeth girl, had seen enough to suggest that Kallystine had used potions to entrap him.
The Copper-Colored Cupids from the eponymous series dip their arrows in Love Potion to make people fall in love whether they like it or not. The original formula of Love Potion was created by the Cupids' own Mad Scientist creator, but they then lost the formula and get their supplies directly from the goddess Aphrodite instead as "the next best thing".
Some of Nanny Ogg's recipes have a very aphrodisiac-like effect, and people have been known to do amazing things after accidentally eating a plateful of something spiced up with her famous Chocolate Sauce with secret ingredients. The description strongly implies that she doesn't use magic, but natural aphrodisiacs. It can't break Granny Weatherwax's self-control, and another character is resistant because he eats a lot, implying that the effect is physical rather than magical.
Mort has a brief mention of "Granny Weatherwax's Ramrub Invigoratore and Passion's Philtre". It's a bit of Early-Installment Weirdness; later books would suggest that Granny sees this sort of thing as more Nanny's area, but at this point in the chronicles, Nanny hadn't been invented yet.
The aphrodisiac version occurs in The '80s pulp series Doomsday Warrior when the Dirty Communists decide to psychologically torment our hero by injecting him with a drug that makes him randy, then chain him to a wall facing a beautiful female captive. As she'd rather lose her virginity by choice to the manly hero than through being gang-raped by the KGB guards, she works out how to slip free of her bonds.
In Dragon Bones, there is an offhand mention of a herbal aphrodisiac that the protagonist's mother had in her garden. It is used as a comparison when one of the characters is tortured, and notices that the torturer is a sadist who gets turned on by it. He compares the effect of his suffering on the torturer to that of said aphrodisiac on more normal people. Which raises the question how he, being underage when he left home, even knows about this.
In Dragonsdawn, Pernese colonist Sallah Telgar wants to settle down, and becomes infatuated with the much-older scientist Tarvi Andiyar. While they are on an expedition together, she doses his food with an aphrodisiac, which leads to her getting pregnant, and they marry; the marriage isn't the most successful, due to Tarvi's preoccupation with his work, although they do have three more children. By the time of Sallah's tragic death, however, Tarvi truly loves her, and he's devastated by her loss.
In a short story from one of the Dragonlance collections, a kender (not Tas) has "borrowed" a pouch from a mage he was travelling with. At the Inn of the Last Home, he finds that while the pouch is perfect for his collection, it is full of a strange powder. He dumps it in the just-inspected ale-brewing equipment. The night the barrel of that particular brewing is served is very interesting at the inn, since the powder is of the love/lust-inducing-at-first-sight variety. Subverted at the end, when Otik Sandeth chooses not to use the doctored ale to gain the wife he longs for.
In Dragonvarld, certain people want Melisande to have a son, because that son will inherit powerful magic which they can point at the Big Bad. They therefore give Melisande and a man in her company a potion which makes them want each other (and also guarantees successful conception). It works, with neither of them knowing that a potion was involved (and therefore believing that they each betrayed their respective long-term partners).
Storm Front Has Harry saying in his ad that he categorically will not make them for people, but Bob, his perverted magical assistant, refuses to help Harry make the escape potion he actually wants to make unless he makes (but not necessarily uses) a love potion too. It contains conventional (perfume, chocolate) and not-so-conventional (excerpts from a cheesy romance novel, a torn-up $50 bill in lieu of diamonds) ingredients. Despite (or perhaps because of) being called a "love" potion, it's more of a really effective aphrodisiac than anything else. Susan accidentally drinks it instead of the aforementioned escape potion when she and Harry are cornered by a demon, and Hilarity Ensues.
Two of the Dresden short stories involve variations on the concept:
"Last Call" has a maenad dose Harry's favorite homebrew beer with a lust-and-violence potion in an attempt to start a riot at a Bulls game to remind people of Dionysus (and teach them "proper respect").
"Love Hurts": A Red Court vampire enchants a carnival haunted house ride to make the riders fall in love, hoping to spread true love, which is anathema to White Court vamps. She draws Harry and the cops' attention when people who shouldn't be in love (like siblings) fall victim and commit suicide. It's noted repeatedly in the series that any sort of mental tampering like this leads to insanity and frequently suicide; it just manifested in the victims Harry was investigating faster because they were siblings and thus had that extra taboo.
In The Eyes of Kid Midas, Kevin tries to use his newfound Reality Warper powers to woo his crush. Ironically, the attempt fails because she's secretly already in love with him, and all he ends up achieving is creeping her out.
In The Gate Of Ivory by Doris Egan, love magic is well-known, but can only induce symptoms, and someone aware of the symptoms is seldom fooled by them. Notably, in one book in the series, a character with a love spell put on them by their captor misinterprets the symptoms (racing pulse, dry mouth, dizziness) as stress reactions to the kidnapping.
One of Laurence Janifer's Gerald Knave, Survivor short stories involves a military project to douse the enemy country with aphrodisiacs so they'd be too busy screwing to put up a fight when invaded. Unfortunately, the chemicals keep leaking, causing the factory workers to get amorous when they're supposed to be working. The author included a comment on the dubious morality of this weapon, especially as the drugs only affect men.
Goosebumps: The book Be Careful What You Wish For has a non-romantic variation where a dorky girl helps an old woman, who turns out to be a witch and gives her three wishes for her kindness. She wishes that the Alpha Bitch in her class who always bullies her will think that she's the greatest person who ever lived. They quickly become BFFs, to everyone else's confusion, but the Alpha Bitch in question becomes so obsessed with her new best friend that she can't stop thinking about her and shows up to her house in the middle of the night.
The Halfblood Chronicles: Elvenbane: A complex multi-stage glamorie is used to by an elven Lady to get one of the half-elven to become completely devoted to her; he doesn't realize she's slowly casting him under a spell, and thinks he's falling in love. Luckily, unfinished glamories are fragile things; physical impacts, such as those from a former slave-lover, tend to disrupt them.
Harry Potter mentions love potions, but their effect and the way they're seen evolves over the course of the books. In earlier books, they're seen as something of a novelty, but in later books, they're seen more or less as date rape drugs. Later books also clarify that no potion can create genuine love, but rather just intense infatuation. Enforcement tends to vary; while they're not allowed at Hogwarts, you can buy them in shops and smuggle them into the school pretty easily.
One of the earliest mentions of love potions is Harry overhearing Mrs. Weasley admit to Ginny and Hermione that she used one in school once, which just elicits giggles from them, as if it's typical schoolgirl antics. It contrasts sharply with the attitudes toward them in later books, particularly with Hermione's angry reaction to discovering that Fred and George are selling them in Half-Blood Prince. Maybe they just grew up a little bit. It's also the source of a common Alternative Character Interpretation for Molly.
In Chamber of Secrets, Lockhart tries to suggest some students visit Snape for advice on brewing love potions.
In Goblet of Fire, Rita Skeeter accuses Hermione of using love potions to make Harry and Viktor Krum fall in love with her. She seems more angry at being tabloid fodder than anything else.
In Half-Blood Prince, we see some of the true effects of love potions. First, we see Harry pick up a Stalker with a Crush who tries to slip him a love potion (but it hits Ron instead, and Harry has to save him). Later, we find out that Voldemort's own mother, Merope Gaunt, used a love potion on her crush, Tom Riddle, and thus conceived Voldemort. Dumbledore speculates that Merope must have made a particularly powerful one for it to work as effectively as it did, but that she felt guilty and stopped giving him the potion in the hope that he would grow to really love her. He didn't, she dropped Voldemort off at an Orphanage of Fear, and thus is the villain's Start of Darkness. Given the nature of Merope's highly dysfunctional family, she's painted as almost sympathetic, but Harry reaches the conclusion that love potions are comparable to dark magic. Neither he nor Dumbledore blame Riddle Sr. for running away from her the first chance he got and never finding out what happened to either her or Jr.
Amortentia, the strongest love potion, is described as the most dangerous potion—compared directly to a potion that could kill dozens of people with a single drop. We never explicitly see its effects, but it is implied to be the variety that Merope used on Tom Riddle. Amortentia has the quirk of smelling differently to everyone, based on what attracts them; Harry smells treacle tart, the woody scent of a broomstick handle, and "something flowery" that he later realizes is the smell of Ginny's hair.
A platonic variation of the Love Potion is also noted within the video game adaptations known as Gregory's Unctuous Unction, a potion that makes the drinker believe they're best friends with the potion giver.
A whole industry of non-functional love spells can be found in Jonathan Strange & Mr. Norrell. There was a spell to store emotions in amber, then when the amber melted the emotions spread to those nearby. Presumably, this could be used with love, although the actual examples were courage and fear for your and the other side's army respectively. It also featured a rather clever use of love spells Childermass buys a knowingly non-functional spell from Vinculus to use on a princess, bringing the wrath of the King down on Vinculus. Turns out he needn't have bothered.
In Kushiel's Mercy, the visiting general of a neighbouring empire gets his magician to make Sidonie fall in love with him using a spell that involves a very small tattoo between her shoulder blades. It also causes her to forget all about her passion for Imriel — though, as it turns out, it's not wholly effective. The spell is broken when Imriel cuts the tattoo from her skin. Needless to say, when she comes around, Sidonie is pissed. In this, the Unfortunate Implications of using a love potion — namely, that it's effectively rape — are fully spelled out.
In Naamah's Curse, one of the villains possesses a magical black diamond that entrances people who look at her, enabling her to become a queen. However, it's stated that this diamond does not compel false desire, or force anyone to be attracted to someone they wouldn't desire otherwise. Instead, it amplifies and enhances any slight attraction the wearer already inspires in people who encounter him/her. The wicked queen was a beautiful woman to begin with, and the diamond enhances her desirability so that anyone who would have been at least a little attracted to her without the diamond feels compelled to worship her like a goddess when she puts it on. It's still pretty damn coercive, though.
The Labyrinths of Echo series by Max Frei is about a world with strong magic, including love potions. It's not clean and reliable, though, and sometimes the victim is poisoned. The surest way to heal this is for the guilty to immediately, ahem, proceed with the seduction to the end. Fortunately, the limitation of the magic means that only very weak and safe variants are used, unless someone is lovesick enough to risk imprisonment just for making it. But the only guy who tasted it in the book managed to die at the first sip anyway — for nothing, because he was already quite charmed in the natural way. The victim, of course, was rather surprised by the new disposition upon revival... but willing to repeat the whole sequence if necessary and claiming he needs regular prophylactics to stay alive. It ended up just very embarrassing, for everyone involved.
— Wait, when I managed to seduce you? Of course sometimes I talk in my sleep and all that, but it never occurred to me that even death has no power to shut me up!
Little Women: The sisters perform a play with a villain who purchases a love potion from a witch, along with poison to kill his romantic rival (probably to avoid that "power of true love" loophole). The witch, however, double-crosses him, stops the princess from drinking the potion, and slips the villain his own poison.
In the Malediction Trilogy, Catherine the witch (in her Back Story) is forced to prepare a love potion for her mysterious and highly dangerous employer. She has no choice but to fulfill the wish, and while the potion works perfectly well, it all backfires horribly, leading to her being banned from the court and forced to live in the poorest slums of the city.
In the Mercy Thompson book Iron Kissed, Tim uses Orfino's Bane to force Mercy to fall in love with and have sex with him. The other characters make it very clear that magic can never be used to get consent.
In the Night World book Spellbinder, Thea accidentally challenges Blaise's skills by saying she couldn't attract her soulmate. Blaise's response is to use a love charm. Not only does this not work, it still doesn't work when he is enchanted to hate Thea.
In On a Pale Horse, Zane is offered the use of a Lovestone by the Magician to seduce Luna (his daughter). Said stone compels instant desire and "is not something you can buy in knickknack shops". Despite being strongly attracted to Luna, and despite her stated willingness to honor her father's bargain (though she has no pleasure in it herself, nor interest in Zane), he declines the offer to use the stone.
In The Perilous Gard, this trope is subverted. Kate thinks Christopher has fallen in love with her sister Alicia. The queen of the fairies offers her a token that will supposedly make Christopher love her, which Kate declines, because she would always know that he only loved her due to a potion. She finds out later that Christopher loves her, and the queen knew that, and the token was most likely nothing at all but a quiet form of revenge on the part of the queen.
Tom Holt's JWW series, beginning with The Portable Door, centers around J.W. Wells' famous "love philtre", which always works — it knocks the drinker out for twenty minutes, and they fall in love with the first person of the opposite sex they see. There have to be something like five or six instances of this throughout the series, nearly always with horrific potential. As in all his books, Holt plays fast and loose with consistency, and a love philtre which "always" works somehow generally finds a way to wear off. At least until the very end of the third book, where the "hero" and "heroine" (if they can be described as such) are finally given such a heavy dose of the thing that they spend the rest of eternity making dovey-eyes at each other.
The aunts in Practical Magic cast love spells for any woman who asks. The only example given in detail is a cautionary one, as her new husband never gives her a moment's peace. However, the reader's viewpoint is almost exclusively on the woman. The effects on the man, or his ex-wife who he was faithful to before the spell and somewhat faithful to afterwards before being specifically hit with a spell to make him leave her, are hardly shown.
Schooled in Magic: They're available outside Whitehall, but banned inside. A love potion's effect can be permanent, and lessened only if redirected onto something else. It's stated any student caught with them will wish they were merely expelled. The ones outside Whitehall apparently don't really work, just give people confidence, and true love potions are much rarer. Later some are shown to be sold which only work if people drink them willingly, to insure a married couple stays in love to conceive a child.
In The Shadowhunter Chronicles, love spells are considered black magic because they impose certain feelings on another person. Witches who trade potions of love must fear severe punishments from the Shadowhunters. However, an exception is made if it is a potion that only increases sexual desire and both are inadvertently ingested. The latter potions are particularly popular by fairies.
Averted in Lois McMaster Bujold's The Spirit Ring. Fiametta tries to create a love ring, but her father explains that the spell only reveals true love, not compels it, and that magically induced true love is a paradox. The spell does work, just not on who Fiametta intended it for.
Corie makes some for a lovesick castle guard in Summers at Castle Auburn. The ethics of this are explored in the piece, as she says her potion will only make the girl notice him, not love him. He has to do the work of getting her to fall for him. Corie could make standard love potions, but she doesn't want to practice "that kind of magic". A more standard love potion was involved in Corie's conception, which is acknowledged as a rape.
Sword of Truth makes mention of the morality issue; using a glamour spell, the series' equivalent of this, is seen by characters as tantamount to rape. Sorceresses who use it are either executed or expelled from the Palace of the Prophets (the Palace has a spell which slows down aging to about 10%, so there is little difference between the two for the exiles).
In the world of Tales from Netheredge two "pleasure drugs" are commonly used — Tiger's Eye and Black Root — that put the recipient into a sexually submissive or dominant mood, respectively. No mention is made of their distribution and use being regulated (but then this is a setting where human trafficking seems to be perfectly legal, too). Clever pharmacists make use of the drugs' side effects as well: for example, a minuscule dose of Tiger's Eye is a part of a healing tonic.
Older Than Print: One version of Tristan and Iseult has the eponymous lovers drinking a mixture from a vial, thinking it was a lethal poison, only to discover instead that it was a love potion. Another version has Isolde's maid giving her a love potion and telling her to use it with her betrothed husband, King Mark. Isolde instead chooses to use it on her beloved Tristan, even though she knows the two of them can't be together. Still another version has them drink it accidentally, mistaking it for wine, or one where Isolde is already in love with Tristan and he alone drinks the potion meant for Ysolde (so she'd fall in love with Mark).
Isaac Asimov, inspired by the Gilbert and Sullivan operetta The Sorcerer, wrote a short story titled "The Up-to-date Sorcerer", in which the Professor's potion works because of Techno Babble instead of magic. It's a slightly more ethical potion than the usual sort, as it only works on people who aren't married. Predictably, it ends up making the pretty young girl fall for the wrong person, and all parties involved try to figure a way out of this mess. When they remember that the potion has no effect on married people, they realize that if the girl marries the guy the potion made her fall for, the potion will no longer work. They do, the potion wears off, they get the marriage annulled, and the girl goes back to dating the guy she was originally interested in.
Villains Don't Date Heroes!: Smarmy reporter/supervillain Rex was apparently using his mind control to build himself a harem. It's strongly implied that he had been raping Fialux this way for months, if not years. It might be for the best that she doesn't remember anything that happened while she was under hypnosis.
In the Vita Nuova, Dante admits that if his speech could fully communicate the worth of his lady, it would turn any of his listeners into lovers.
Piers Anthony's Xanth series includes magical "love springs". In this case, "love" is used as a euphemism — drinking from such a spring causes one to be compelled to mate with the first creature of the opposite sex that one sees, regardless of species. Love springs are supposedly responsible for the numerous Half Human Hybrids and Mix-and-Match Critters that exist in Xanth. What's worse, if you drink from it twice, you fall in love twice. Without losing your first love. Only time is effective.
In The Source Of Magic, Bink is distracted by an unseen "enemy" trying to stop him from discovering the source of magic. Bink cannot be harmed by magic, due to his Talent, but he can be tricked into drinking from a Love Spring, because "falling in love" is not magical harm, just "embarrassment". Sure enough, despite already being married, he drinks from one and then meets Jewel. Eventually, it gets cancelled out by an absence of magic, but by then Jewel has fallen in love with him naturally.
The characters plan to employ a more traditional one (i.e. causing love instead of lust) to solve the magic-induced Love Triangle between Prince Dolph, Nada, and Electra. Electra is cursed to love Dolph and will die if he doesn't marry her. Dolph loves the sexy Nada instead, and Nada just considers him a friend but must marry him for political reasons. To fix this, Electra will marry Dolph, take a potion to nullify the magic love she has for him the next day then divorce him, and then Nada will take a love potion so she can marry Dolph. Instead, Electra's potion doesn't work because she truly does love Dolph, Dolph decides he loves her back during their one night of marriage, and Nada doesn't need to take the potion after all.