Most people have come across Reddit threads where users claim “That pregnancy prevention pill made me gain weight,” often followed by heated back-and-forth debates — or seen X users posting, “IDK if I’ve gained weight, if it’s the pill, or if I’m pregnant.”
According to a statement in 2019 from The Faculty of Sexual & Reproductive Healthcare, there is a perception that weight gain is a common side effect of contraceptive use and this is often cited as a reason why women do not initiate or do not continue contraception.
But the belief that both types of contraceptive pills — combined and progestogen-only — cause weight gain is a myth, according to a reproductive immunologist at Imperial College London.
“For both, there’s no evidence. It’s been studied a lot and actually for a really long time, so oldest of these studies was published as early as 1978” Dr Male told The Independent.
Scientific reviews support this. One analysis of the combined pill found no clear evidence of significant weight gain. Another review on progestin-only pills reported low-quality evidence overall.
Dr Male explained that some individuals may notice changes in their bodies after starting it, which could be where the theory gained legs. In some cases, the combined pill can cause water retention, which may lead to a feeling of bloating, Dr Male explained.
“Lots of people feel kind of puffy and gross before their period, and that’s why some people might gain some water weight if they’re taking combined hormonal contraception” Dr Male said.
“Because it’s water, it’s not there forever, so it will come off if you change contraception” she added.
Despite the science being clear, the myth still persists. Dr Male believes that while weight changes can occur, they’re often due to other factors.
“It’s actually to do with the kind of change in lifestyle that has caused you to want to take a hormonal contraceptive.”
“ Sometimes it can happen because you know, you’ve started taking the pill because you’ve met a lovely guy and he’s a great cook and you’re staying in a little bit more, so you might put on weight” she added.
With social media surpassing Google as the go-to search tool for young people, and hormonal birth control usage declining sharply, addressing related online misinformation is more urgent than ever, experts warn.
Instagram and TikTok are now the preferred search engines for Gen-Zers when seeking local results, according to a study carried out in 2024 by marketing technology vendor SOCI.
For Gen-Z internet users in the US, Instagram was first, with 67 per cent saying they use it for searches. TikTok is the second choice at 62 per cent of the 18 to 24 demographic search, while Google is third at 61 per cent.
NHS data shows the proportion of women using the pill as their main form of contraception has dropped from 47% in 2012-13 to 27% in 2022-23.
“Online misinformation about the pill and other forms of hormonal contraception is a real cause for concern” Dr Sue Mann, the NHS clinical director for women’s health said.
Dr Male told The Independent that people should pay attention to how their body responds to the pill over time.
“If you’ve been taking a pill for a while, like maybe more than three or six months and it’s still not quite right for you, then it’s definitely worth talking to a doctor or a contraceptive nurse because there are lots of options and you can find something that works for you” she said.
