Why Do We Forget About the Nocebo Effect, Even Though It Is Stronger Than the Placebo Effect?

Expectations of Negative Effects

The nocebo effect refers to a situation where a person anticipates a negative treatment outcome so strongly that it triggers real health problems or at least discomfort. This is not imaginary — people who experience nocebo truly suffer. The existence of this effect also makes sense from an evolutionary perspective, as humans are “programmed” to anticipate threats to their health.

Specifically, the nocebo effect can occur, for example, when a doctor prescribes a new treatment, explains its possible side effects, and the patient subsequently experiences some of them. Nocebo can also manifest as reduced treatment effectiveness. This was demonstrated in analgesic studies — when patients were warned in advance that a medication could worsen pain, the therapy sometimes failed to work altogether.

Nocebo is not limited to treatment situations; it can also complicate assessments of the health safety of new technologies. This was seen in the case of 5G networks, which, according to conspiracy theories, cause headaches and insomnia.

Measuring the Effects

A recently published study compared the strength of the placebo and nocebo effects by conducting an experiment on 104 healthy participants (including controls) involving stimulation with an electric current (in some cases simulated), assessing pain from a burn stimulus. Assessments were conducted twice: immediately after the experiment and again one week later.

The hypothesis was confirmed: at both time points, the hyperalgesic nocebo effect was consistently stronger than the analgesic placebo effect, and during the second measurement, it occurred more frequently, meaning it lasted longer. Psychological variables were also taken into account in the assessment.

How It Spreads

The tricky aspect of the nocebo effect is that it does not only occur in individual situations — it can be transmitted. If a patient observes someone experiencing symptom worsening after receiving a certain treatment, their own therapy can show a similar effect. It does not matter whether this is a real situation or a simulation. The experience can even be transmitted through social media, as happened during the COVID-19 pandemic with fears about vaccination.

A 2022 study showed that the nocebo effect can be amplified in individuals who are already worried about side effects, feel anxious, or frequently seek out health-related information on social media.

Impact on Treatment Adherence

Awareness of the nocebo effect is important because it can minimize negative expectations and, in turn, reduce side effects. It should be taken into account in placebo-controlled trials, where it appears as adverse effects in the placebo group, since it can affect treatment adherence and even lead to discontinuation. In clinical practice, the aim should be to harness the placebo effect and avoid the nocebo effect.

What can doctors do to minimize the nocebo effect? For instance, they can frame discussions with patients about new treatments in a positive way, such as by emphasizing that the side effects listed in the package insert are rare and that most patients experience no problems at all.

Editorial Team, Medscope.pro

Sources:

1. Sauders C., Colaguiri B. You can catch the nocebo effect from family, friends - even social media. But what is it actually? Conversation.com, 20 Mar 2025. Available at: www.theconversation.com/you-can-catch-the-nocebo-effect-from-family-friends-even-social-media-but-what-is-it-actually-249844.

2. Kunkel A., Schmidt K., Hartmann H. et al. Nocebo effects are stronger and more persistent than placebo effects in healthy individuals. eLife 14:RP105753, doi: 10.7554/eLife.105753.1.

3. Tan W., Colaguiri B., Barnes K. Factors Moderating the Link between Personal Recounts of COVID-19 Vaccine Side Effects Viewed on Social Media and Viewer Postvaccination Experience. Vaccines (Basel), 2022 Sep 26;10(10):1611, doi: 10.3390/vaccines10101611. Available at: www.pmc.ncbi.nlm.nih.gov/articles/PMC9610806