What is the nocebo effect?

It sounds far-fetched, but it’s true. What you think about a medication affects how well it will work for you. In other words, if you believe that a prescription will ease your symptoms it will—and vice versa. When you worry that a treatment plan will have bad side effects, or do nothing to ease your pain, it can become a self-fulfilling prophecy. It’s called the nocebo effect.

What is the nocebo effect?

Nocebo responses occur when your negative expectations about a treatment cause you to experience negative symptoms from taking medication. For example, if your health care provider mentions back pain as a potential adverse event, you may experience back pain—even if you take a sugar pill. Or, if you read an article about how that prescription can trigger migraine, you might get a headache after taking it. This reaction is known as the nocebo effect.

Placebo effect vs. nocebo effect

Many people are familiar with the placebo effect. It occurs when you experience the benefits of a medication because you believe it will be helpful even if that medication is inert. The nocebo effect is the opposite phenomenon. Negative perceptions lead to ineffective treatment, even for powerful medications.

Placebo means, “I will please,” in Latin. Nocebo means, “I will harm.” Both thought patterns can have a meaningful impact on your health outcomes.

How the nocebo effect works

As we know from the more-studied placebo response, the power of verbal suggestion alone can cause the mind to believe the body is experiencing a positive (or in this case, negative) side effect of drugs. This means that simply mentioning those adverse effects can make you believe that you are physically experiencing those problems, according to Erin Nance, MD, a New York City–based orthopedic surgeon. However, practitioners are bound by medical consent to discuss all the possible risks involved with medical treatments, meaning patients will occasionally be told something negative that causes them to experience more pain and dysfunction—creating a bit of an ethical dilemma.

“These effects occur with inert treatment because a person’s expectations and the conditions surrounding a treatment, or the ‘ceremony’ of a treatment, can have profound effects on our brains, and our brains have profound effects on our bodies,” explains Harrison Weed, MD, an internal medicine physician at The Ohio State University Wexner Medical Center.

Additionally, patients who read through all the possible side effects listed for a medication are more likely to report suffering one or more of those side effects, as are patients who are anxious in general, or are afraid of a side effect in particular. Even patients who feel their provider doesn’t care for them, is unconcerned, or too busy to know them, are more likely to report adverse effects of treatment.

From a neurobiological standpoint, what happens within the brain is similar to what happens when you imagine a visual scene or doing physical activity. Those parts of your brain light up. “In practical terms, imagining something is happening is enough to activate those portions of the brain associated with that thought, or worry, or pain, which leads to the perceived side effects becoming their reality,” says general practitioner Giuseppe Aragona, MD.

Examples of the nocebo effect

Nocebo responses can appear in clinical trials, everyday clinical practice scenarios, and even instances when no medication is actually prescribed or taken. Understanding the various ways the nocebo effect presents can help patients be prepared—and even make it less likely to occur.

Perhaps the most obvious place people expect the nocebo effect is in clinical or drug trials. “People in clinical trials who receive inert treatments often report higher rates of common symptoms, such as headache, stomach upset, dizziness, fatigue, or generalized weakness than do similar people not in clinical trials,” says Dr. Weed. For example, a patient in a research trial receives the placebo for a new medication that helps to heal distal radius fractures faster, and is told one of the side effects is fatigue. If the patient starts to experience fatigue it is most likely due to the nocebo effect, adds Dr. Nance.

People taking statins often experience the nocebo effect. Perhaps partially because the side effects of this type of medication are so widely covered in the news, people may have negative expectations. The risk of muscle pain from taking statins is less than 5%. Yet, recent studies indicate that nearly 30% of patients stopped treatment due to muscle pain—even if they were part of a control group and their treatment was actually a placebo.

Alex Tauberg, MD, even sees the nocebo effect in his chiropractic practice: On an X-ray, evidence of degenerative change is likely to be present in anyone above the age of 30. Because osteoarthritis is extremely common, we are unable to claim that osteoarthritis seen on X-rays is the cause of low back pain. In fact, osteoarthritis is just as common in people with no pain or dysfunction as it is in people with pain. “Yet, when we show these X-ray results to patients, it increases their pain and disability levels as they believe there is something structurally wrong with their body,” Dr. Tauberg explains.

5 ways to prevent the nocebo effect 

You don’t have to be a victim to your negative expectations. Use these strategies to fend off the nocebo response.

1. Discuss the positives. “Being informed while believing that you will experience a positive outcome is the best way to maximize the benefit from your treatment outcome,” says Dr. Nance. “If a patient knows that postoperative tingling is less than 1%, then reframing the outcome as 99% of patients have normal sensation will help foster a positive outlook.” Even if your provider doesn’t deliver the information this way, it’s possible for you to reframe the information in terms of positive expectations.
2. Focus on the benefits. Redirect your focus to the benefits of the medication or treatment rather than the potential side effects. Using your energy to think about the positives of a medication can reduce the risk of a nocebo response, says Dr. Aragona.
3. Make a plan. “Providers can educate patients about likely side effects and empower patients with a plan for addressing negative side effects and for informing the provider,” explains Dr. Weed. Knowing that you have a plan in place for coping with a potential negative effect as well as an open channel of communication with your health care provider  can lessen the anxiety that causes the nocebo phenomena.
4. Exhibit care. Providers can develop the processes and skills to show their care for their patients, including spending enough time with them. When possible, choose a medical professional who you feel cares about you and your well-being and who can and will listen to your concerns.
5. Be honest. Practitioners should exercise “contextualized informed consent,” which takes into account possible side effects, the patient being treated, and the particular diagnosis involved, according to Ted J. Kaptchuk, BA, professor of medicine at Harvard Medical School.

If you have a specific concern or fear about a potential side effect, be honest with your health care provider  or pharmacist. Healthcare professionals can explain how likely it is to occur. Knowing your risk is small, and what to do if you experience it, can help fend off the nocebo effect. When all else fails, think positive thoughts.