You likely know what a placebo is, but have you heard of nocebo effects?
“The nocebo effect is the opposite of the placebo effect. It describes a situation where a negative outcome occurs due to a belief that the intervention will cause harm. It is a sometimes forgotten phenomenon in the world of medicine safety. The term nocebo comes from the Latin ‘to harm’.”The nocebo effect
It’s not obvious from the name, but a nocebo is simply the opposite of a placebo.
What is a Nocebo?
But why would you want to give someone a placebo that makes them feel worse?
“The nocebo effect can be influenced by ‘media storms’. Widespread dissemination of concerns about an adverse reaction to a medicine leads to an increase in the number of reports of the adverse reaction.”The nocebo effect
But if a lot of people are telling you that you are going to have an adverse reaction when you do or take something, the idea of a nocebo is that you will be more likely to actually have that negative reaction.
“This study found that the rate of nocebo responses in placebo arms of COVID-19 vaccine trials was substantial; this finding should be considered in public vaccination programs.”Frequency of Adverse Events in the Placebo Arms of COVID-19 Vaccine Trials
And that’s what we have seen in the clinical trials for the COVID vaccines.
“Twelve articles with AE reports for 45 380 participants (22 578 placebo recipients and 22 802 vaccine recipients) were analyzed. After the first dose, 35.2% (95% CI, 26.7%-43.7%) of placebo recipients experienced systemic AEs, with headache (19.3%; 95% CI, 13.6%-25.1%) and fatigue (16.7%; 95% CI, 9.8%-23.6%) being most common. After the second dose, 31.8% (95% CI, 28.7%-35.0%) of placebo recipients reported systemic AEs. The ratio between placebo and vaccine arms showed that nocebo responses accounted for 76.0% of systemic AEs after the first COVID-19 vaccine dose and for 51.8% after the second dose.”Frequency of Adverse Events in the Placebo Arms of COVID-19 Vaccine Trials: A Systematic Review and Meta-analysis
The folks who got placebos – saline placebos, had a significant number of adverse reactions.
“Common nonspecific symptoms such as headache and fatigue, which the study’s findings showed to be particularly associated with nocebo, are listed among the most common AEs after COVID-19 vaccination in many information leaflets. There is evidence that this sort of information may increase nocebo mechanisms such as AE-related anxiety and expectations. Furthermore, the information might cause a misattribution of commonly experienced nonspecific symptoms (eg, headache or fatigue) as specific AEs due to vaccination, even if these symptoms might have occurred in the absence of receiving any treatment.”Frequency of Adverse Events in the Placebo Arms of COVID-19 Vaccine Trials: A Systematic Review and Meta-analysis
While this doesn’t mean that all adverse effects are nocebo responses, it is definitely something to think about the next time you give or get a vaccine.
“Highlighting the probability of not experiencing AEs might also be beneficial.”Frequency of Adverse Events in the Placebo Arms of COVID-19 Vaccine Trials: A Systematic Review and Meta-analysis
Also know that:
- nocebo effects seem to be more common in those with a tendency toward somatization reactions (turning psychological distress into physical symptoms)
- nocebo effects can be increased if you only talk about the negative aspects of vaccination – overlooking the benefits
- misinformation about vaccines can likely increase nocebo effects
- people who are already hesitant to get a vaccine may be more prone to nocebo effects
“The nocebo effect can be minimised by reducing negative expectations and anxiety about treatment, and placing discussion about the likelihood of adverse effects into the context of treatment benefit”The nocebo effect: what is it, why is it important and how can it be reduced?
More on Placebos and Nocebos
- Where are the Saline Placebos?
- Where are the Double Blind Placebo Controlled Randomized Trials about Vaccines
- Are There Any Long-Term Studies On Vaccine Safety?
- Are Vaccines Causing Long-Term Health Problems?
- 7 Things You Need to Know About COVID-19
- COVID-19 Vaccination Questions and Answers
- Get All of Your COVID-19 Questions Answered
- The Fatal Flaw in the Anti-Vaccine Movement
- How Pediatricians Should Talk to Vaccine Hesitant Parents
- Vaccine adverse effects may be in our heads — a systematic review and meta-analysis
- Frequency of Adverse Events in the Placebo Arms of COVID-19 Vaccine Trials: A Systematic Review and Meta-analysis
- ‘Nocebo effect’: two-thirds of Covid jab reactions not caused by vaccine, study suggests
- The nocebo effect: what is it, why is it important and how can it be reduced?
- The nocebo effect
- Nocebo: Placebo’s Evil Twin
- Placebo Again.
- Nocebo Nonsense
- Nocebo Mass Delusion
- Frequency of Adverse Events in the Placebo Arms of COVID-19 Vaccine Trials
- More dubious statements about placebo effects
- The nocebo effect of drugs
- How do nocebo effects in placebo groups of randomized controlled trials provide a possible explicative framework for the COVID-19 pandemic?
- Accentuate the positive: Counteracting psychogenic responses to media health messages in the age of the Internet
- Nocebo-Prone Behavior Associated with SARS-CoV-2 Vaccine Hesitancy in Healthcare Workers
- How to prevent, minimize, or extinguish nocebo effects in pain: a narrative review on mechanisms, predictors, and interventions
- Can Positive Framing Reduce Nocebo Side Effects? Current Evidence and Recommendation for Future Research
- Minimizing nocebo effects by conditioning with verbal suggestion: A randomized clinical trial in healthy humans