How the pill can change (and even rewire) your brain

A third of women have come off the pill due to mental health effects like anxiety and depression.

We put these mini hormone bombs into our bodies for decades, and we don't know a smidgen of the science behind them – and that’s why women now need to be armed with more information about how hormones work in every form of contraception, from the pill to the patch, coil, injection and implant.

Women (and some non-binary and trans people) have instinctively known for years that hormonal contraception affects their mood and sex drive, but that's mostly been dismissed, and we've been gaslighted. All that mattered was not getting pregnant.

Yet UK pill use has halved in the last ten years, so we are voting with our feet. At last, we have new data, science and brain scans to prove what's happening and give us the confidence to speak out – and change to contraception that suits us better.

Researching my book Everything You Need to Know About the Pill, I found some major surveys which showed that 77% of women experience "non-lethal" side effects, a third have come off the pill due to mental health effects like anxiety and depression, and 21% reported lowered sex drive.

These "non-lethal" side effects may not be life-threatening, like blood clots on the pill, but they are life-ruining for some. New brain scans from Scandinavia show women's serotonin (the happy hormone) falls by around 10% on the pill – liveable for some, a disaster for those already facing mental health problems.

I talked to Abby Fry, 28, a fashion brand manager in London, about her experience on the pill, which nearly led to her quitting university. When she was studying marketing and management at the University of East Anglia, she went on Rigevidon, the NHS’s cheapest, first-choice pill, which contains the synthetic hormones levonorgestrel progestin and ethinylestradiol. It was partly because she was experiencing adult acne.

“I was in second year, and it did help my skin a little bit, but then made it worse. I started getting side effects of low mood. I was snappy and had really high anxiety. I had no problem with my coursework before, but suddenly I struggled to do it at all.”

Eventually, Abby had a full-blown crisis. She talked to her mother, who advised her to stop taking the pill. Within a week, she started to feel better. “I realised I’d been horrible to my friends; I’d been a cow.”

She tried another combined pill, Yasmin, which is anti-androgenic, which means it lowers testosterone levels and can be helpful for acne, but it didn’t make much difference, so she dropped it too. She’s looking for a better solution. “I was under a black cloud at university. I can’t believe I nearly gave up something I loved for the pill.”

Like Abby, none of us can guess how each pill or form of hormonal contraception will affect us individually, but as Professor Jayashri Kulkarni, who is at the forefront of investigating mental health changes and contraception at Monash University in Australia, says: “There’s not a stainless-steel plate at waist level which stops hormones getting up to our heads. Basic neuroscience tells us that the hormones oestrogen, testosterone and progesterone are potent brain steroids.”

A new Women’s Brain Health program has opened at the University of California. Researchers are scanning female brains on and off synthetic hormones and examining effects like raised stress levels, changes in spatial ability, and even facial recognition and motor skills.

Dr Caitlin Taylor, who is starting the research, said: “I am still filled with total indignation, wondering how the pill has been around for 60 years, and we’ve only just started asking these questions.”

Of course, for some women, hormonal contraception can be brilliant, keeping hormone levels steady. It can prevent the hormonal surges that often cause migraines, it can sometimes help lower endometriosis flare-ups, and it can keep women who suffer premenstrual syndrome (PMS) or the more debilitating premenstrual dysphoric disorder (PMDD) on a steady hormonal keel.

The hormones in our brains naturally change every day, and we get a creative and sexual surge as oestrogen peaks in the middle of the month – but that flatlines for some on the pill. There’s good news on the way, though. The new smaller hormonal coils like the Kyleena and the Jaydess have lower hormones than the Mirena and are less likely to cause low mood in women, according to a new Danish study.

In other advances, there are new pills containing safer body-identical oestrogens made from soy, like Zoely, Drovelis and Qlaira, but they still contain synthetic progestins. The new pills are approved by the NHS – but rarely prescribed as they are more expensive. Professor Kulkarni did a small trial of the Zoely-type pill on patients with PMDD and found that 75% had improved mood, so it’s worth experimenting with different pills.

Good sources of information are The Lowdown – a sort of Trip Adviser for contraception – with honest reviews from users, and the sexual health charity Brook. But there’s still a huge gap in women’s knowledge and scientific research. Why are we so badly informed on something that matters to us every day? We deserve better.

Everything You Need to Know About the Pill (but were too afraid to ask) is out now. Follow Kate Muir on Instagram @pillscandal.