MedPlus Mart

What is a placebo effect?

A placebo is an inert substance, typically a tablet, capsule or other dose forms that does not contain an active drug ingredient but results in a positive health outcome due to an anticipation that it will help the patient. A doctor’s way of interaction with the patients may also result in a positive response which is independent of any specific treatment.

The more a person believes he/she is going to benefit, the more likely they will experience the benefit. The placebo effect forms part of the human tendency to respond positively to a healer. A patient’s problem may be alleviated by something which does not have a medical basis.

To distinguish this power of positive thinking from the medicine’s true medical benefits, companies that seek government approval of a new treatment often use placebo-controlled drug studies. If patients on the new drug fare significantly better than those taking placebo, the study helps support the conclusion that the medicine is effective.

The scientific study of the placebo effect is dated to a paper published in 1955 on “The Powerful Placebo” by the anesthesiologist Henry K. Beecher (1904-1976). Beecher concluded that from the   26 studies he analyzed, about 32% of patients responded to a placebo.

Placebos have been particularly effective on conditions such as:

How does a placebo work?

Based on a person’s expectation, it is possible that the body’s own chemistry can cause effects similar to what a medication might have caused.

Placebos have just not been providing positive reinforcement but also have measurable physiological effects. They have been observed to speed up pulse rate, increase blood pressure, and improve reaction speeds, for example, when participants are told they have taken a stimulant. Placebos have the opposite physiological effects when participants are told they have taken a sleep-producing drug.

People who are given a placebo can also experience negative effects. These include symptoms like nausea, diarrhea, and constipation. A negative placebo effect has been called the nocebo effect.

The ethics of using a placebo?

Placebo effects have been reported to occur in 21 to 40 percent of patients depending upon the study type. In one survey, only three percent of U.S. physicians reported using actual sugar pills as placebos, but 41 percent said they had used over-the-counter painkillers and 38 percent said they had used vitamins as placebos for their patients. Sixty-eight percent of physicians described the placebo to their patients as a potentially beneficial medicine, and roughly two-thirds of the doctors felt the practice was ethical.

In another study, physicians used reduced doses of anti-inflammatory medications in combination with a placebo to successfully treat psoriasis patients. Combining active drug with placebo may be effective in diseases that involve the mental state and immune system, including asthma, multiple sclerosis, and chronic pain. Reducing doses by combining with placebo treatment could also reduce side effects, addiction potential and cost.

Medications that do have active ingredients but aren’t proven to work on the patient’s particular condition can also be placebos. There have even been placebos in the form of surgery, injections and other types of medical therapies. Some people believe that complementary and alternative medicine count as placebos, too.

Some people don’t find it wrong in a doctor prescribing a placebo. After all, he or she is doing it to help the patient. But others see the practice not only as harmful, but unethical, deceptive and possibly even illegal.

The psychology of placebo effect

One theory behind the placebo effect is the subject-expectancy effect. When people already know what the result of taking a pill is supposed to be, they might unconsciously change their reaction to bring about that result, or simply report that result as the outcome even if it wasn’t.

Others believe that people who experience the placebo effect have become classically conditioned to expect relief when they take medication.

Though in both these theories, the patient has a built-in expectation of the outcome they differ in that the subject-expectancy effect is subjective because it’s based only on what the patient reports. But there have been measurable physical responses associated with taking a placebo, which lends strength to the classical conditioning theory.

Studies have however proved that the brain isn’t being “fooled”, it actually responds in a different way to a drug and a placebo. Some studies have also suggested that susceptibility to the placebo effect might also be genetic. Placebos not only have resulted in measurable effects in the brain, they’ve also been shown to relax muscles and nerves to bring pain and symptom relief to patients. So while the placebo effect is indeed in your head, it’s not just psychological.

Prescribing Placebos

Often, doctors prescribe placebos because they have no other form of relief to offer the patient. Either there is no effective medication available, or the patient can’t take the commonly used medications due to side effects or other reasons.

Doctors sometimes prescribe a placebo because the patient insists on taking some type of medication. Although it might sometimes be a case of simply giving the patient what he or she wants, doctors who prescribe placebos for this reason are more likely to decide that giving the patient nothing would be more harmful.

According to surveys, the two most commonly prescribed placebos were over-the-counter pain pills like aspirin and vitamins. Other doctors have prescribed antibiotics or sedatives. Critics argue that none of these are true placebos because they all contain ingredients that are active in some way, even if they aren’t known to work for the patient’s particular condition.

The controversy surrounding placebo prescription

The American Medical Association created a policy regarding placebos stating that “physicians may use placebos for diagnosis or treatment only if the patient is informed of and agrees to its use”. This is the biggest issue that critics raise: Doctors are essentially lying to their patients when they prescribe something that they know isn’t proven to work for the patient’s particular condition.

There’s also a very real danger in prescribing drugs like sedatives and antibiotics as placebos. A sugar pill, a vitamin or an aspirin isn’t generally likely to cause any problems. But drugs like sedatives and antibiotics could be doing more harm than good. Many sedatives are habit-forming, so the patient could develop a dependency on a drug that wasn’t even supposed to work on his or her particular condition to begin with. Doctors who prescribe antibiotics when they’re not absolutely necessary may also be contributing to the rise in strains of antibiotic-resistant bacteria such as MRSA.

The debate will continue concerning not only what constitutes a placebo, but whether doctors should continue to use them. But as long as many people believe that the placebo effect works, they’re not likely to go away anytime soon.

Written by Medplus