# Nocebo effect

> Genuine symptoms produced by the expectation of harm rather than by the exposure itself — the inverse of the placebo effect.

- Canonical URL: https://emfbase.com/glossary/nocebo-effect
- Collection: Glossary
- Record id: `glossary:nocebo-effect`
- Status: verified
- Last verified: 2026-08-12
- JSON: https://emfbase.com/api/glossary/nocebo-effect

## Key values

- **Category:** health

## Definition

A nocebo response is a real, sometimes measurable symptom caused by a person's expectation that something will harm them. It is the mechanism the EHS provocation literature converges on: in 46 blinded experiments symptoms tracked what participants believed about the exposure rather than whether the field was actually present. Calling a symptom a nocebo response says nothing about whether it is real or disabling — it addresses only what triggered it, and therefore what is likely to help.

## Sources

- `rubin-2010` Rubin GJ, Nieto-Hernandez R, Wessely S — Bioelectromagnetics 31(1):1–11 (2010). *Idiopathic environmental intolerance attributed to electromagnetic fields (formerly 'electromagnetic hypersensitivity'): an updated systematic review of provocation studies*. https://pubmed.ncbi.nlm.nih.gov/19681059/ — peer-reviewed, link checked 2026-08-12
- `who-ehs` World Health Organization (2005). *Electromagnetic hypersensitivity (WHO backgrounder, December 2005; formerly Fact sheet 296)*. https://www.who.int/teams/environment-climate-change-and-health/radiation-and-health/non-ionizing/hypersensitivity — government, link checked 2026-08-12

Data licence: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Dataset version 2026.08.1. Retrieved from EMFBase, https://emfbase.com.

This record is reference data, not medical or legal advice. Regulatory limits, scientific guidelines and precautionary values are labelled separately and answer different questions.