Never Trust a Hair Tonic

It seems that a man's greatest fear is losing his hair, and once it's gone, it's gone for good. Which is why a bald character is bound to try using some kind of product that promises to grow back their hair. This product never works. Or rather, it usually works too well, with way more hair sprouting than necessary, and often in places that it wasn't wanted. Other side effects may occur as well, including, but not limited to, the hair turning an unnatural color or what little hair was left falling out completely.

For similar forms of hair-related hilarity, see My Hair Came Out Green and occassionally Kaleidoscope Hair.

Anime and Manga

 * On Ranma ½ Genma is quite embarrassed about his baldness and has tried all kinds of cures. This doesn't stop him from trying new remedies. There was the one that only works when he's angry, the one that comes from a one-of-a-kind dragon's whisker, and so forth.
 * Mahou Sensei Negima has a female variation, when short-haired Ako thinks she should grow her hair out to be more attractive. A (not so) helpful denizen of the magic world promptly gives her a magic hair-growth potion, which works perfectly for all of a minute before the hair begins to engulf her.
 * An early Inuyasha story has two demon brothers kidnap Kagome. She thinks they simply want to eat her, but it turns out one of them is severely balding and embarrassed about it, and he has heard you can get a hair growth potion by boiling down a human maiden. At hearing this, Kagome angrily insists they eat her instead. (Not 100% really this troupe, since we never learn whether the potion works - but the kidnapping does lead to the demon losing his last few hairs - before he is killed.)

Comic Books

 * A Donald Duck comics story "Black Wednesday", written by Carl Barks, features Uncle Scrooge selling hair tonic to the "Chillyboot Indians", which actually causes baldness. Donald later returns with a hair tonic made by Gyro Gearloose; that one works too well.

Film

 * In Cloudy with a Chance of Meatballs, one of Flint's failed inventions is "Hair Unbalder." A little bit squirted on the scalp causes his dad to burst out with hair on his entire face.
 * Similarly, some hair-voodoo worked by Dr. Facilier in The Princess and the Frog initially grants a man a full head of hair, but it quickly spreads to the rest of his body.
 * In the SpongeBob SquarePants movie, King Triton tries to use some hair tonic, but accidentally it gets into his eye. So his eyeballs grow hair.
 * In Pete's Dragon, when Dr. Terminus comes to town, the townspeople confront him about his various medicines that didn't work the last time he was there, including one man whose hair turned from gray to pink, thanks to the doctor.
 * In the Canadian family film The Peanut Butter Solution, a boy loses his hair after seeing ghosts, then grows it back with the titular solution. It doesn't know when to stop, of course.
 * In The Naked Gun 33 1/3, there's a flashback with the detectives in what's supposed to be the 1970s. Drebin has long hair, and when Nordberg appears, he has an Afro so huge he can't fit through the door. After the movie returns to the present, Ed says to Nordberg, "I do remember! You were one of the first cases for minoxidil."

Literature

 * Crocodile tears in the book Hubert's Hair Raising Adventure by Bill Peet.
 * The title charater in The Witch's Son by Vivian Van Velde goes through several variations on regrowing a girl's golden hair, none of which work.
 * In The City Of Silent Revolvers, the main character is blackmailed into switching identities with a conman, and ends up getting in trouble for all of his earlier scams. A faulty hair tonic called Probatbicol is one these scams.

Live Action TV
"Why any boy of Bobby’s age, or any age, would be investing in something as outmoded and unidentifiable as “hair tonic” remains to be explained. As any kid on the show could tell the writer, the old hair-tonic routine is right out of Our Gang. Let’s face it, we’re long since past the “little dab’ll do ya” era."
 * An episode of Doctor Who called "Planet of the Ood" has a similar situation. Ood Sigma constantly hands his boss, the Big Bad of the episode, a drink which he claims is hair tonic. It turns out to be
 * The Two Ronnies did a skit at an inventors' conferrence, one of the inventors had created a hair tonic with two problems. First it makes the hair grow pink and second is that it falls out if the drinker has a shock.
 * In the Better Off Ted episode "Father Can You Hair Me?", Ted tests an experimental hair tonic (packaged as an aerosol) on his arm, causing massive amounts of hair to grow not only on Ted's arm, but also on his desk.
 * In (what turned out to be) the final episode of The Brady Bunch Bobby gets some mail-order hair tonic to sell, which turns Greg's hair orange. In the memo attributed to Robert Reed about how weak the show's internal logic had become, he complains about this in particular:


 * A Good Eats episode on celery has a sketch of a celery drink just made regrowing hair, then shows Alton paying the man whoes hair supposedly grew back in private.
 * Seinfeld: George Costanza's Chinese baldness cure. Whether it actually works is moot, because it smells horrible and he never manages to keep it on his head long enough.
 * One early episode of Married... with Children had Al and Steve freak out about their baldness and try an experimental "tonic" to reverse it. Not only did it not work, but Al's dog Buck took to the stuff better than their hair did.
 * Another episode features an accidental hair tonic made by the daughter experimenting with paint. It works wonders, but has the nasty side-effect of.
 * In a Dream Sequence on The Dick Van Dyke Show Rob's hair turned into lettuce, because he was given a baldness preventative that was basically oil and vinegar - aka salad dressing.
 * Two and A Half Men feature 'Captain Terry's Spray On Hair' as well as pills, both of which Alan try before going on dates. The first ends up running down his face when warm and the pills cause bizarre folical growth.

Newspaper Comics

 * One Bloom County arc featured a compound made from cat sweat, originally intended as an underarm deodorant, which caused massive hair growth wherever it was applied. Its creator immediately turned it into a hair tonic instead. Sales were ridiculously, dangerously good for a while... and then customers' hair started falling out. As in, all at once, poof-gone-you're-a-bowling-ball.
 * And it makes you start saying "ACK!", presumably because it was made from Bill the Cat's sweat.
 * It's happened a few time in Curtis, often thanks to the titular character's misuse of a Flyspeck Island substance.

Theater

 * Pirelli's Miracle Elixir from Sweeney Todd: The Demon Barber of Fleet Street, which turned out to be, in Sweeney's words, "an arrant fraud, concocted of piss and ink."

Web Comic

 * Doc Rat featured Mr Pigg complaining to the chemist that the tonic he'd purchased which promised to "add body to your hair" had caused him to sprout hair everywhere. Turned out he'd read the label upside down; it actually said "adds hair to your body".

Web Original

 * Gaia Online has an item called Gro-gain: "New and improved, all natural formula guarantees DRAMATIC new hair growth, or your money back!" It can give you a huge mustache on your crotch, "Coiling Pit Hair", "Unforgivable Leg Hair", "Evil Hair" on your head, and more. It can even turn you into a "Fearsome Hairy Beast". It even caused a child character to develop a Casanova Wannabe alter ego and experience Rapid Aging.
 * Hazmat of the Whateley Universe is cueball-bald due to his failed hair tonic. Aquerna arranges for Phase to look at it and plans are put into place to sell it as a hair-removal application for women.
 * The SCP Foundation had a hair tonic which caused its users to be "completely torn apart from the inside by torrential amounts of internal hair growth"

Web Animation

 * Used for Squick factor when Disco-Bear from Happy Tree Friends dunks his head in hair tonic after burning his afro. His hair grows back...but in his eyes. Cue Eye Scream when he cuts his eyes off with a razor as he tries to remove the hair from his eyes. He slips on a bottle of hair tonic and falls to the tub of hair tonic and grows more hair.
 * And not just Disco-Bear, Cuddles coughs out his hairy organs before choking to death after mistakingly drinking a bottle of the formula that fell into his soda cooler and a bottle bursts open on Flaky while driving, causing her spines to impale her passenger, Handy.

Western Animation

 * In the Looney Tunes short "Rabbit of Seville," Bugs Bunny rubs and sprinkles a number of tonics on Elmer Fudd's scalp, only for flowers to sprout from his head instead of hair.
 * In The Simpsons episode "Simpson and Delilah", "dimoxonil" actually does grow hair on Homer's head, but the Snap Back to baldness comes as a result of not being able to afford it and his health plan not covering it. Hasn't minoxodil (of which dimoxonil was obviously a parody) become a lot cheaper than it was in 1990? Homer could probably afford it now!
 * The Simpsons used this trope twice. At the end of the episode "Barting Over" Homer acts in a commercial for Viagra-gaine, a drug that grows hair and is also for impotence which side effects are said to include loss of scalp and penis.
 * The Mother Goose and Grimm cartoon had a hair tonic which could grow hair on billiard balls, as advertised...but it couldn't grow hair on anything else.
 * Billy in The Grim Adventures of Billy & Mandy tried some hair tonic and ended up growing hair all over his body looking like a Bigfoot. It turns out that all he has to do was wash it off.
 * In Dexter's Laboratory, Dexter makes a hair tonic for Dee-Dee after she accidently cuts off one of her pigtails. Despite repeated warnings to use only one drop, Dee-Dee uses the entire bottle. Three guesses what happens next.
 * In one episode of Courage the Cowardly Dog, "Hothead", Eustace applies for an experimental hair tonic, with the warning that the recipient not be angry when in use. Little does Eustace know, is that every time he uses the tonic, it amplifies his anger to the point that he can cause explosions (and to add insult to injury, he doesn't grow any hair other than one long strand at the end of the episode, which makes him so angry he destroys the entire house.
 * Gargamel and Brainy learned this lesson the hard way in The Smurfs episode "Symbols Of Wisdom" when they both try to grow their own beards.
 * Phineas and Ferb has a female example in "Bad Hair Day", when Candace uses a machine her brothers built for her in order to fix her hair after a botched attempt to cut it herself. Of course, she can't wait the designated time and decides to turn 30 mins into 10 seconds by cranking up the power level. Cue Candace getting covered in hair and being mistaken for a tangerine orangutan.
 * A Freaky Stories story involves a boy inventing a hair tonic that, while capable of growing hair on any surface, doesn't seem to work on him. After dousing himself with it in a panic, he realize all to late that it takes longer for the tonic to grow hair on a human, and it turns him into a werewolf.