The Nocebo Effect


We’ve all heard of the placebo effect, but how familiar are you with the nocebo effect?

The placebo effect is a common term that we come across in studies done to test the response of patients to an experimental condition, like a new drug or treatment. These studies are done in a controlled clinical trial. These trials often feature a group that is given a pill or injection with no active ingredients while another group is given a pill or injection with active ingredients. These pills look similar and are administered to both groups and outcomes are subsequently measured.

The placebo effect is noted when the group with the inactive pill or injection improve their symptoms significantly. However, the opposite is also possible. When some patients have worse symptoms than when they began the trial, it is known as the nocebo effect. This post will cover the nocebo effect, its causes, and what can be done to help mitigate its effects. Let’s explore!

What is the Nocebo Effect?

The nocebo effect refers to unpleasant side effects experienced by taking a drug. These unpleasant experiences are not linked to any actual cause. Instead, they are mainly related to the patient’s negative expectations. 

With more optimistic expectations, the patients will experience the placebo effect where their symptoms improve.


Walter P. Kennedy first introduced the nocebo effect in medicine back in 1961. He associated this phenomenon with the harmful effects caused by a placebo. Since then, this effect has been linked to the placebo and active drugs in clinical trials. 

It is important to note that this phenomenon affects patients in a drug trial and those receiving their usual treatment for different conditions. So, the nocebo effect could affect anyone and lead to adverse side effects when on a treatment option.

The medication may be excellent and the best option to treat the specific conditions, but with a negative expectation, the nocebo effect kicks in. The patient begins to experience the adverse effects they imagine or have heard may be possible. 

Root Causes

A study by frontiers in psychiatry shows that the nocebo effect is caused by negative expectations, classical conditioning, and observational learning. As you can see, there is no mention of any drugs, showing that it is a phenomenon that needs more understanding.

In most cases, these causes result from what patients find out about the drugs or treatments they are on. Medical professionals must get informed consent from their patients before starting any treatment.

Informed consent means the doctors must reveal the benefits and disadvantages of the treatment options. This shows that the patient is fully aware of the adverse side effects expected when they begin their treatment. 

Study shows that the content and the way information is presented to the patient influence the nocebo effect. Therefore finding ethical ways to communicate with patients while maintaining patient autonomy is essential. 

Classical conditioning and observational learning relate to the experiences a patient has had or what they have been told to believe. For example, a study done in 1996 showed different responses to drugs of different colors. 

The findings were based on patients associating red, yellow, and orange pills with stimulant effects while blue and green drugs with sedative effects. The study concluded that the color of a drug affects its perceived action and effectiveness.

Therefore when patients are conditioned to believe certain drugs have a specific effect, they will most likely experience that despite it being false. 

How the Nocebo Effect Affects Individuals

Individuals experiencing this effect may find it challenging to stick to any treatment option. Despite the treatment’s effectiveness, the patient will opt to discontinue it since the symptoms only worsen. 

The nocebo effect will lead to frustration for both physician and patient, seeing that each treatment they try may result in unpleasant effects. 

In addition, when patients try a complementary treatment like acupuncture, the nocebo effect may also be an issue. They may not have positive results if they have negative speculations on the cost of acupuncture and its effectiveness, expect it to have adverse effects, or be painful. 

Studies show that reducing patient information about the side effects of treatment may reduce nocebo. This would allow the patient’s symptoms to improve when receiving treatment.

However, withholding such crucial information is unethical and should not be encouraged, especially in the medical sector. Instead, physicians are urged to use proper information and communication techniques to help minimize the nocebo effect while delivering truthful information on the risks.

The Nocebo Effect on Fitness

The nocebo effect is also something you may witness in the fitness industry. As a personal trainer, spotting the nocebo effect is essential to help you guide your trainees expertly. 

If clients claim not to see results or experience adverse effects from training, explore their expectations and beliefs when exercising. For example, if your trainee is told they’ll experience muscle soreness after a workout, you may find that this becomes the case. 

However, should the muscle soreness become exaggerated to an extent where the trainee prefers to avoid the specific exercises that made them sore, then the nocebo effect may derail your client’s progress in training significantly. 

Studies show negative expectations when doing a new exercise or sport may induce adverse responses. In addition, the study suggests that negative belief adversely affects training performance.

As a personal trainer, finding ways to affirm your clients and help them believe that they can get through different exercises is essential. Then, go a step further to show them that different activities are possible to help relieve them from negative expectations.

You can also warn them about side effects like muscle soreness but try to deliver the information in a more optimistic approach. Doing this will allow them to avoid focusing too much on the negative but on getting through the exercises. 


How to Deal with the Nocebo Effect

The nocebo effect can significantly impact a person’s health, treatment, and overall fitness. Therefore, finding ways to combat it and encourage better circumstances is essential. 

Encouraging a mood has proven to be a great way to help prevent the nocebo effect and keep the client or patient on track. Therefore, if you as a trainer can induce a positive attitude during training sessions, this could yield better results and prevent the nocebo effect.

In addition, other findings suggest that invoking a placebo response is a great way to diminish the nocebo effect. This allows the individual to stick to their plan and relieve their symptoms over time. How would you introduce the placebo effect to counteract the nocebo effect? Take, muscle soreness for instance; have your client foam roll after their sessions (which is purported to diminish DOMS) and also suggest they apply a muscle rub containing arnica after your session. You may find that your suggestive client responds well enough to these efforts to reduce muscle soreness and may experience diminished DOMS as a result.

About the Author:

Nicole McCrayNicole McCray is an experienced content writer with a passion for all aspects of wellness. She worked a side gig at a yoga studio for years before becoming a mom, and absolutely fell in love with holistic and alternative therapies during her first pregnancy. She’s been proclaimed the “health nut” amongst family and friends, and when she’s not writing, Nicole can be found studying to become a health coach and reading up on all aspects of healthy living!


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