What’s the Nocebo Effect? Examples and Effects on Your Health

You’ve probably heard of the placebo effect. That’s the idea that people can be more likely to experience a benefit from a medication or other intervention if they expect it to help. Even if it’s not a valid treatment.

But there’s another side to the placebo effect. A kind of evil twin, you might say.

It’s called the nocebo effect. And it can also impact how you experience the effects of medical interventions. But for the worse.

What’s the nocebo effect? And what does it mean for your health? We talked with wellness and preventive medicine physician Robert Saper, MD, about it.

What’s the nocebo effect?

The nocebo effect is a phenomenon where people experience very real negative effects from a medical intervention if that’s what they expect going in. It’s all about the power of suggestion.

For example, if you’re rolling up your sleeve for your annual flu vaccine and the nurse tells you, “This is going to hurt.” Chances are, it’s going to hurt. A lot.

If they tell you, “You might feel a quick prick, but it goes away fast.” You can be more likely to report that it wasn’t so bad.

The nocebo effect is an example of how our minds and bodies work together — that our thoughts and feelings can influence our physical well-being.

That’s not to say that the nocebo effect (or the placebo effect for that matter) is all in your head.

But as Dr. Saper points out, “It’s not all in your body either. There’s a strong mind-body connection. The input we get from our bodies travels up neurons to the brain. The brain has complex ways of processing that information. For example, when we’re experiencing pain, the brain has the capacity to send information down to the body that can mitigate the sensation of pain. Or it can amplify it.”

And the effects go far beyond pain. Think about that “butterflies in your belly” feeling when you get nervous. Or how you may tremble when you’re scared. Or how your face gets hot when you’re angry.

Your thoughts, feelings and emotions very directly affect your physical self. And negative expectations can influence your perception of the effects.

Placebo effect vs. nocebo effect

The placebo effect describes how people can have a positive outcome that wouldn’t, scientifically, be expected.

Like sugar pills improving your headache. Or, according to some studies, improving stretch marks with cocoa butter.

The nocebo effect says that you can have a bad experience with a particular intervention or event, if that’s what you expect to happen.

“With the placebo effect, we see people gaining a benefit from an intervention, even if there’s no scientific reason for that benefit to occur,” Dr. Saper explains. “The nocebo effect works in a similar way, but with negative consequences.”

In both the placebo and nocebo effect, the expectation of what you’ll experience affects how you perceive the experience.

Nocebo effect examples

Examples of the nocebo effect are all around us.

If you drink a cup of coffee late in the day, you may have a harder time falling asleep. Even if the brew is decaf.

If a friend advises against going to a particular restaurant because they didn’t like their meal there, you can be less likely to enjoy yours.

If the weather forecaster emphasizes the drastic cold front bearing down on your area, you might feel the chill more acutely — even through your parka, hat, scarf, mittens and snow boots.

In medical contexts, the nocebo effect is in full force, too:

• Some researchers argue that the way healthcare providers describe the pain or recovery time after a child has a concussion can set the stage for increased pain and a delayed recovery.
• Another study suggests that some pain and fatigue people reported after receiving COVID-19 vaccines may have been influenced by others around them reporting having those effects.
• Other research reports that the nocebo effect may explain why some people experience more muscle pain after taking statins. Though muscle pain is known to be a potential side effect of these medications, the nocebo effect may make it worse.

Even the way a healthcare provider shares information with you can raise the possibility of the nocebo effect.

“If, for example, you go to a doctor and ask about a treatment and they say, ‘Well, I don't think it's going to help you, but I suppose you could try it,’ not only will you lose any potential placebo effect, but it may even have a negative outcome,” Dr. Saper shares.

“On the other hand, if I suggest a treatment with a fair amount of hope and optimism attached to that recommendation, you might be more likely to have a better experience with it.”

How the nocebo effect affects you

Let’s be clear: Medical interventions can have side effects. There can be pain. They may not be effective. And they can be tough to manage.

No one is arguing that negative effects can’t happen.

But knowing that the nocebo effect exists can give you a reason to look more critically at the potential for a connection between your expectations and the effects they have on your well-being.

Say you hurt your back shoveling the driveway. Your doctor recommends physical therapy. But you tried that a few years ago for your knee and it didn’t work.

So, you assume that PT won’t work for your hip either. You go. But (no surprise to you) your hip still hurts. Now you’re looking at surgery.

If you had higher expectations of therapy, perhaps it may have been more successful. And you could have avoided a more invasive procedure. Maybe not. But maybe so.

Or maybe you have high blood pressure. And you blame your blood pressure medication for upsetting your stomach. So, you stop taking the meds. That’s a recipe for unmanaged hypertension, which can do serious damage throughout your body.

But was the nausea really a result of taking the medication? Might there be something else at play? It’s tough to say. But worth considering.

Bottom line

“Our minds and bodies have some potential to improve or, conversely, worsen some types of symptoms. In some instances, that potential can be harvested for good use,” Dr. Saper affirms. “And that can be empowering to understand and use to your benefit.”