The powerful nocebo effect

Everyone has heard of the placebo effect, our ability to produce a powerful healing response triggered by the belief that a treatment will be good for us. Our brain can reduce pain or other symptoms depending on how much we believe in a treatment or how much we believe that we can improve our symptoms. This phenomenon is well known and has been widely written about, but have you heard of the nocebo effect?


The nocebo effect is the opposite of the placebo effect, it’s our ability to activate a response that can cause pain or other symptoms depending on whether we think something is dangerous or will do us harm. If we believe that something dangerous has happened to us or that there is something wrong, even if there isn’t, it can lead to symptoms. I’m going to describe two examples of when this has happened, both of which are case studies written up in medical journals:


The first one is a 29 year old builder, who jumped down off a step and landed on an upturned 15cm nail, which went straight through his boot. He was taken to A+E were it was reported that the slightest movement of the nail caused extreme pain so he had to be sedated with fentanyl and midazolam. The nail was then removed from the boot and the boot removed from his foot and when the boot was removed, the doctors found the nail had actually gone between his toes and not through his foot. His pain improved almost immediately once he realised there was no damage to his foot (Fisher et al., 1995).


The second is a 26 year old American man who was enrolled in a medical trial that was testing anti-depressants. After an argument with his girlfriend he took an overdose of the pills he was taking in the trial. After arriving at hospital he collapsed with low blood pressure and needed intravenous fluids to maintain his blood pressure. The doctors at the hospital contacted the trial to see what medication the man had taken. They found out that he actually been in the placebo group and after he was told this his symptoms disappeared in 15 minutes. (Reeves et al., 2007).


In the case of the builder the protective part of his brain thought that his foot had been damaged and therefore caused intense pain to protect the foot even though there wasn’t any damage. In the second case the man who ingested the medication believed the pills were going to cause an adverse effect and so he felt the effects he anticipated. These are both examples of how our beliefs or our perceptions can influence the symptoms we feel, making symptoms worse and causing pain.


In both cases their symptoms settled down very quickly once they realised there was nothing wrong, but what would happen if we continued to believe there was something wrong? It could mean that we continue to experience pain even when there is no damage.


I see this happen a lot with people who have had MRI scans on their lower back and have been told they have a prolapsed disc causing the pain. Often their belief from that point onward is that their back is in some way weak and not structurally sound. This gives the message to their nervous system that the back needs protecting and this can lead to them experiencing on-going pain to protect the back. It is the same with people who have had x-rays on their knees and told that they have osteoarthritis and in many other instances.


The belief that an area of the body isn’t structurally sound leads people to think that it is harmful to do activity and they begin to adapt their lives to avoid certain movements or to avoid the pain. This in turn means they become de-conditioned and the body doesn’t get the movement it requires. A viscous circle is then created, which further enhances the pain or means people experience pain for longer.


I feel this is one of the major reasons why treatments don’t work, because if we don’t address the belief that something is wrong, then the brain will continue to produce the pain, despite having treatment.


That’s why addressing someone’s beliefs about their pain is one of the first things I do. If someone thinks that something is damaged when it isn’t, then we need to change that to help improve the pain.  I often give people different techniques to help to do this. Two of the techniques I use most often are positive affirmations about the affected area of the body and visualising the area of the body being strong and healthy rather than being weak. By changing how we think about the affected part of the body it helps to remove the nocebo and takes away the need for the protective pain response, thereby giving people more confidence to begin being active again.




Fisher JP, Hassan DT, O’Connor N (1995) Minerva. BMJ 310: 70.


Reeves, R.R., Ladner, M.E., Hart, R.H & Burke, R.S. (2007) Nocebo effects with antidepressant clinical drug trial placebos. General Hospital Psychiatry Vol 29 (3) pp 275-277

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