Do Placebos Work? Here’s Why Doctors Sometimes “Prescribe” Them

More and more physicians are prescribing placebos as antidotes for a range of ailments from pain to nausea to high blood pressure. A 2015 survey published in the journal PLoS One, for instance, found that 45 to 80 percent of U.S. internists and rheumatologists said they had used placebos in their practice.

But before you jump to the conclusion that doctors are deceiving patients with sham treatments, know that there’s plenty of evidence that placebos actually work, hence the term “placebo effect.” That’s when you feel better even when the improvement can’t be attributed to any active properties in the drug. According to the American Cancer Society, up to a third of people experience the placebo effect. And some placebos are just as effective as regular treatments, according to a 2019 article in the Australian Journal of General Practice.

What is a placebo?

Oleg Elkov/ShutterstockHere’s where it gets confusing. There’s no one definition for a placebo. In the strictest sense, a placebo is a drug (or injection or device) with no active properties, according to the University of California, Davis. They’re commonly used in clinical trials as the “nothing” that a “something” (for example, a new treatment) is measured against, says Jon Tilburt, MD, professor of medicine and biomedical ethics at the Mayo Clinic in Rochester, Minnesota.

“When I was in training we called them sugar pills or inert fillers,” adds Carol Ott, PharmD, clinical professor of pharmacy practice at Purdue University College of Pharmacy in West Lafayette and Indianapolis, Indiana.

Types of placebos

In real life, though, placebos can be both inert (like a sugar pill) or active—a real drug or intervention but one for which there’s no plausible explanation why it might work for that specific condition. According to the study in PLoS One, doctors in the United States tend to prescribe active placebos more than inert ones. This is also true in other parts of the world, including Australia.

But to confuse things even more, doctors and patients can differ in their opinions of what a placebo is. “The doctor may think something is a placebo but the patient doesn’t,” says Dr. Tilburt. Take essential oils as one example. The physician may not think they’ll do anything but the patient does, so the doctor “prescribes” lavender oil. And what some people might call a placebo, others might term a “non-drug therapy,” says Dr. Ott. In other words, a placebo may only be a placebo in the eye of the beholder. (Learn more about the basics of essential oils.)

What are placebos prescribed for?

Given the issues with terminology, the world of placebos—both active and inert—could be almost limitless, but studies have pinpointed settings where they seem to be widely used. The 2019 article reveals that doctors most often prescribe placebos for viruses, insomnia, pain, fatigue, depression anxiety, cramps, and cough. The most common placebos used to address these conditions were antibiotics, followed by vitamins or minerals, complementary treatment, painkillers and antidepressants, physical therapy, cough mixtures, and melatonin. Most of these qualify as active placebos.

Research also points to the effectiveness of inert placebos for arthritis pain, insomnia, symptoms of angina and irregular heartbeat, and pain and disability linked to back pain. Placebos have also been found to help test anxiety and teen depression.

Why do doctors prescribe placebos?

One reason—and a good one—is because doctors really believe that the act of prescribing something will help the patient. “Most doctors want patients to feel not abandoned but accompanied,” says Dr. Tilburt. “There’s pretty good data for the role of relationships in health outcomes.” This may, in fact, be part of the reason why placebos actually do work. A less noble reason provided by doctors was because the patient asked for or even insisted on getting some kind of treatment. A hectic schedule seems to encourage placebo use: A 2013 study published in the journal PLoS One found that doctors who worked more days tended to prescribe more placebos. (Here are some signs you may need to fire your doctor.)

How do placebos work?

No one really knows how the placebo effect works, but there are several theories and some emerging science. There’s the idea that strong doctor-patient relationships can contribute to healing; another hypothesis states that placebos are evidence of mind over matter—you believe you will feel better, and so you do. “It’s a complex dance of expectations,” Dr. Tilburt says. (There’s also something called the “nocebo effect“—expecting that a treatment won’t work or could make things worse leads to bad outcomes.) The placebo effect may also involve feeling in control. “If I’m a patient with chronic symptoms, I want to leave the office feeling hopeful, like I can do something about my condition,” says Dr. Tilburt.

But research is starting to tease out specific mechanisms. In one study, brain scans showed that placebos seemed to change brain connectivity in people with painful arthritis of the knee. A research review published in the Canadian Journal of Cardiology posits that placebos activate pain pathways as well as motivation and reward pathways in the brain.

How do I know if I’m getting a placebo?

People in clinical trials at least know that they might be getting a placebo: “That’s part of informed consent,” explains Dr. Ott. “People understand the potential of not getting the active drug.” If you’re in a doctor’s office, on the other hand, the doctor (or nurse or any other medical professional) should tell you before he or she prescribes a placebo. There is no gray area here. The American Medical Association (AMA) says that doctors can only ethically use placebos if they tell the patient and explain to them why. Unfortunately, there is evidence published in The Journal of Medicine and Philosophy that doctors do neglect to inform patients. If you’re being prescribed medication or a procedure—or any kind of treatment—ask what it is, why you’re getting it, and how it works. You can even inquire outright if it’s considered a placebo. Here are some more questions doctors think you should ask.

But will a placebo still work if I know it is a placebo?

Surprisingly, yes. This may have to do with the doctor-patient relationship being “activated.” The AMA states that “the skillful use of reassurance and encouragement, thereby building respect and trust” can produce a “placebo-like effect.” The AMA also notes that lying or otherwise deceiving a patient may undermine the patient-physician relationship and even lead to harm. Or the effect may have to do with other unknowns related to the placebo. According to the AMA: “A placebo may still be effective if the patient knows it will be used but cannot identify it and does not know the precise timing of its use.”

Are placebos harmful?

This is definitely true when antibiotics are prescribed as an active placebo for viral illnesses, as the Australian survey and numerous other studies have shown. Antibiotics have no effect whatsoever on viruses and also contribute to antibiotic resistance, but doctors may prescribe them to mollify a patient. While a single course of “placebo” antibiotics may (or may not) harm a patient, it does contribute to the growth of bacteria that are resistant to treatment. “Doctors . . . often find themselves in situations of trying to get a patient out the door [by prescribing antibiotics], but then you also have these collateral public health consequences which are really kind of tragic,” says Dr. Tilburt. The American Academy of Family Physicians, for one, frowns on this practice. You can read more about antibiotic-resistant superbugs here.

In general, placebos shouldn’t be physically harmful, and it’s absolutely your right to know if you are getting one—whether it’s active or not.