Our Beliefs May Influence the Side Effects of the Pill

Why do so many women stop taking the pill despite its proven protection against pregnancy? New research from the University of Sheffield suggests the answer may lie in the mind as much as the body.

A team surveyed women who had used oral contraception and found that negative expectations and beliefs about medicines strongly influenced reported side effects.

Oral contraception side effects and discontinuation rates

Oral contraception remains one of the most widely used methods of birth control worldwide. The pill is highly effective in preventing pregnancy, yet discontinuation rates are high: as many as 60% of users stop taking the pill within 2 years, often because of side effects.

The most commonly reported side effects of pill use include mood changes, fatigue, nausea, acne and breast tenderness. Some of these can be explained by the pill’s pharmacological action; however, many are non-specific and not unique to oral contraception. Evidence from placebo-controlled trials has shown little difference in reported side effects between women given an active pill and those given a placebo – hinting at the possibility that at least some experiences are psychological in origin.

The nocebo effect – termed the “evil twin” to the placebo – describes negative symptoms that arise from expectation rather than from the drug itself. Factors such as anxiety, prior beliefs about medicines and negative information circulating on social media can amplify how symptoms are experienced. However, in the context of oral contraception, this area has been largely overlooked.

The new study recruited 275 women, between 18–45 years old, who had used the contraceptive pill in the previous 18 months. Participants completed an online survey that asked about their experiences of symptoms, their beliefs about medicines and whether they thought specific symptoms were side effects of the pill.

“The contraceptive pill gets a lot of negative attention, particularly on social media, and we were interested in how these negative views could be influencing the way women are experiencing oral contraception,” said co-author Dr. Rebecca Webster, a lecturer in psychology at the University of Sheffield. “The side effects are very real, but could some of them have a psychological component? If they do, that means we could develop interventions to help people deal with them.”

The team focused on a set of psychological factors that have been linked to nocebo effects in other medical settings. These included:

• Expectations about side effects
• Beliefs that medicines are harmful or overused
• Perceived sensitivity to medicines
• Levels of trust in how medicines are developed

They also measured anxiety and how often participants sought out information about medicines. The main outcomes were a side-effect attribution score (how strongly symptoms were linked to the pill) and whether women had continued or discontinued pill use.

Almost every participant (97%) reported experiencing at least 1 symptom while taking oral contraception. Those with higher expectations of side effects were much more likely to attribute their symptoms to the pill. The remaining three psychological factors were also associated with higher attribution scores. Anxiety and information-seeking had little impact.

The scores also predicted discontinuation.

“For each one-unit increase in side-effect attribution score, individuals had 2.43 times higher odds of discontinuation,” said the authors.

Over the 18-month study period, 54% of participants continued with the pill, while 46% stopped – some switching to another method, others abandoning contraception entirely.

Reducing discontinuation by addressing expectations around oral contraception

The findings suggest that at least some negative experiences with oral contraception are shaped by psychology rather than the pharmacology of the pill, which could help explain why so many women discontinue use despite its proven effectiveness.

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If expectations and beliefs influence side effects, then these same factors might be possible to change.

Previous work in other areas has shown that educating about the nocebo effect may help reduce side effects. In the context of oral contraception, such strategies could reduce discontinuation and, in turn, lower rates of unintended pregnancy.

However, the study has clear limitations. It was cross-sectional, meaning the researchers cannot say for certain whether negative expectations caused symptoms or whether women who experienced symptoms developed more negative beliefs. The sample was predominantly young and white, which limits how far the findings can be generalized. The data also relied on self-reported symptoms, which are open to recall bias.

Future research will need to test these associations prospectively and across more diverse groups, including older women and women from different ethnic backgrounds. Studies that trial specific interventions in clinical practice would also show whether changing expectations can improve women’s experiences of the pill.

“It is important to acknowledge how some women’s experiences of oral contraception are impacted by the nocebo effect. With this information, women can make more informed decisions about their use of oral contraception. This is particularly so with younger women who may be exposed to more negative messaging around use of the pill through greater use of media platforms,” said lead author Lorna Reid, from the University of Sheffield.

Reference: Reid L, Webster RK. Exploring the relationship between medicine related beliefs and side-effect experience among white oral contraceptive users in the UK. Perspect Sexual Reproductive. 2025;57(2):133-137. doi: 10.1111/psrh.70012

This article is a rework of a press release issued by the University of Sheffield. Material has been edited for length and content.