“Merci, periactin!” French TikTokers are praising the hay fever drug to help grow their breasts and bellies – but experts warn the antihistamine is being ‘misused’ for weight gain.

You’ve heard of a diabetes drug used to lose weight; but it’s the antihistamine that helps people gain weight that’s causing a stir in Europe.

Periactin, the commonly used name for the drug cyproheptadine, is being touted by TikTok users in France and the US to help them achieve sultry curves – including bigger breasts and breasts.

Across social media platforms, women are crediting their drug use for giving them hourglass figures with defined, curvy hips – but experts are warning people looking to put on weight that antihistamines aren’t the answer.

The Telegraph reports that the drug is being pulled from shelves across France after social media erupted with TikTok influencers hailing the drug to help them boost their derriere.

And it’s not just in France that the drug has taken off – as influencers in the US are also encouraging people to take periactin to gain weight.

A common, over-the-counter drug for hay fever is being touted by TikTokers as helping them improve their breasts and abs. Pictured: US TikToker Avi, who says periactin helped him gain weight

Periactin is an over-the-counter antihistamine that relieves a variety of allergy-related symptoms, including itching and rash, vomiting, sneezing, and coughing.

However, in the past, it has also been used to promote weight gain due to its appetite-increasing side effect.

And patient reviews seem to back up the drug’s use for weight gain, with people using WebMD to credit periactin with helping them pack on the pounds.

A young woman who discovered she was taking the appetite suppressant said she gained ‘almost a pound a day’ when taking just one periactin pill a day.

French TikToker Romy hailed the benefits of periactin which she says helped her gain 10kg – and stressed to her followers that they shouldn’t fear its side effects.

Fellow TikTok user Mayreen claimed she managed to gain nine kilos in just one month and said ‘thanks periactin’ as she credited the drug for doing so.

She claimed she went from £94 to £125 while taking the drug, but then dropped back to £110 after four months off it.

A US-based influencer named Avi revealed in a clip on her TikTok channel that she gained weight after taking periactin because it increased her appetite.

Posting a video of herself sitting in the passenger seat of a car, Avi, who suffers from the eating disorder ARFID, reveals that taking the drug has helped her eat more than once a day.

She posted the clip with the caption: ‘I have new stretch marks!!!!’

A viewer asked Avi if she recommended the weight gain drug; after her doctors had suggested periactin.

Avi replied: ‘Yes! I have to take it at night before it makes me tired, but otherwise no problems with it.’

But it’s in France that the drug is taking TikTok by storm – prompting France’s national drug safety agency to ban it as an over-the-counter drug.

From July 10, periactin will be available only by prescription in France; much to the dismay of hundreds of women who are using antihistamines to improve their assets.

According to the Telegraph, a statement released by the agency this week said: “As part of our ongoing efforts to promote the appropriate use of drugs and prevent their misuse for cosmetic weight gain, we are changing the conditions for prescribing and dispensing of cyproheptadine.

“Despite the information measures put in place since 2022, this misuse continues, as do the risks associated with it. Changes to the prescribing and dispensing conditions are designed to limit this misuse.’

A French TikToker named Romy joined the platform last year to promote the drug, which she claims helped her gain 10 kilograms.

In the caption of her video, she encouraged viewers not to fear the side effects of taking the drug, which can include hallucinations, insomnia and palpitations.

Another TikToker named Mayreen claimed she had managed to gain nine kilos in just one month thanks to the drug – and posted a clip on TikTok saying ‘thanks periactin’.