Nocebo

The term nocebo refers to an effect in which a person's negative expectations or beliefs lead to undesirable or harmful effects, even though no active therapy or harmful substance is administered (Požgain I et al. 2014).

The nocebo effect is the opposite of the placebo effect. It is known that a placebo is a substance without a medical effect that has a positive effect on the state of health because the patient believes that the substance is effective.

Characteristics of the nocebo effect:

• Expectation of negative effects: If a person expects to experience side effects when taking a drug or treatment, this may actually lead to these side effects, even if the drug is inactive or harmless (Colloca L 2024).
• Psychological factors: The nocebo effect is strongly associated with psychological factors, such as anxiety, stress and negative thoughts about health.
• Physical reactions: The symptoms triggered by the nocebo effect are real and may include physical discomfort such as pain, nausea or fatigue.
• Drug information: Information about possible side effects of a drug can increase the nocebo effect. When patients are informed about many possible side effects, they are more likely to experience them.

Examples:

• If someone complains of a headache after taking a new medication because they have previously heard that headaches are a common side effect, this could be an example of the nocebo effect.
• Nocebo reactions refer to negative outcomes of active medical treatments in clinical trials or in practice that cannot be explained by the pharmacological effects of the treatment. Nocebo effects can be triggered by verbal suggestions, previous negative experiences, observation of others experiencing negative outcomes, and other contextual and environmental factors (Evers AWM et al. 2018; Colloca L 2024).

The nocebo effect is an important concept in medicine as it emphasizes the importance of communication and education in patient care. Physicians and healthcare providers need to be aware of how information about treatments and their potential side effects can influence patients' experiences.

In psychiatry, the placebo effect plays a significant role in most psychiatric disorders, including depression, anxiety, addiction and, contrary to expectations, schizophrenia.

1. Colloca L (2024) The Nocebo Effect. Annu Rev Pharmacol Toxicol 64:171-190.
2. Evers AWM et al. (2018) Implications of Placebo and Nocebo Effects for Clinical Practice: Expert Consensus. Psychother Psychosom 87:204-210.
3. Požgain I et al. (2014) Placebo and nocebo effect: a mini-review. Psychiatr Danub 26):100-107.