What do you call medicine that doesn't do anything?: Understanding the Placebo Effect

October 11, 2025 •

3 min read

Studies have shown that up to 40% of patients may experience a positive response to a medicine that doesn't do anything, otherwise known as a placebo, showcasing the profound power of the mind-body connection in healing. This phenomenon is far from imaginary, involving real neurobiological changes that can affect a patient's symptoms.

Quick Summary

A placebo is an inactive treatment, such as a sugar pill, used in clinical trials to study a new drug's efficacy. The placebo effect is the beneficial response a patient experiences due to their expectation of relief. It is the opposite of the nocebo effect, which involves negative outcomes stemming from harmful expectations.

Key Points

Placebo Definition: A placebo is an inert substance or procedure, like a sugar pill, without direct therapeutic properties, used primarily for scientific comparison in clinical trials.
Placebo Effect Mechanisms: The beneficial placebo effect is driven by a patient's positive expectations, classical conditioning, reduced anxiety, and the release of naturally occurring pain-relieving neurochemicals.
Nocebo Effect: The opposite of the placebo effect, where a patient's negative expectations about a treatment lead to harmful or adverse outcomes, such as experiencing side effects from an inert pill.
Clinical Trial Importance: Placebos are the 'gold standard' for validating new treatments, ensuring that any perceived benefit from a new drug is significantly greater than the psychological effects of receiving treatment alone.
Ethical Dilemma: Deceptively prescribing a placebo to a patient is considered unethical in modern clinical practice, as it undermines trust and the therapeutic doctor-patient relationship.
Inactive Ingredients: Unlike placebos, inactive ingredients (excipients) in real medication serve functional purposes like absorption and stability, though they can rarely cause allergies or adverse reactions.

What is a Placebo?

A placebo is a substance or procedure with no known therapeutic value, often used as a control in medical studies. The term originates from the Latin for “I will please,” referencing its historical use to comfort rather than cure patients. Common examples include sugar pills or saline injections.

There are pure placebos, which are completely inert, and 'impure' placebos, which have pharmacological effects but not on the condition being treated. While deceptive use of pure placebos in clinical practice is considered unethical, impure placebos are sometimes used.

The Power of the Placebo Effect

The placebo effect describes beneficial health outcomes resulting from a patient's expectation that an intervention will help. This involves complex neurobiological and psychological processes, leading to real physical changes. Theories include:

Expectation: The patient's anticipation of feeling better triggers a response.
Conditioning: The ritual of taking medication can become associated with relief through classical conditioning.
Anxiety Reduction: Feeling cared for can reduce anxiety and stress-related symptoms.
Neurochemical Release: Placebos can induce the release of natural pain-relieving chemicals like endorphins.

The Flip Side: The Nocebo Effect

The nocebo effect is the opposite of the placebo effect, where negative expectations lead to harmful outcomes. Patients expecting pain or side effects are more likely to experience them, even from an inert treatment. This can happen after being informed of potential side effects in clinical trials. The nocebo effect can manifest as increased pain, negative side effects like nausea, and higher withdrawal rates from studies. The way information is presented is crucial in minimizing this effect.

Placebos in Clinical Trials

Placebos are essential in modern randomized controlled trials (RCTs) to test new drugs. RCTs typically compare a group receiving the experimental drug with a group receiving a placebo. Double-blind trials, where neither participants nor researchers know who gets which treatment, help isolate the drug's true effect from psychological factors. A drug is only deemed successful if its effects significantly exceed those in the placebo group. Ethical challenges arise when an effective standard treatment exists, leading some to argue for comparisons against the best available therapy instead of a placebo.

The Complex Ethics of Placebo Use

Using placebos in standard clinical practice, outside of controlled research, is ethically debated. While historically used to appease patients, modern medical ethics largely prohibits deceptive use of inert substances. Deception can damage patient trust and the doctor-patient relationship. The American Medical Association's Code of Medical Ethics states placebos can only be used with informed consent. Research into open-label placebos, where patients know they are receiving a placebo but are informed of the potential for a placebo effect, shows promise for harnessing this mind-body connection ethically.

The Components of a Pill: Inactive Ingredients

It is important to differentiate placebos from the inactive ingredients, or excipients, found in real medications. These include fillers, binders, dyes, and preservatives that serve functional roles like ensuring stability or absorption, not direct therapeutic effects. While generally safe, some excipients can cause allergic reactions or intolerances in certain individuals.


Feature	Placebo Effect	Nocebo Effect
Associated Outcome	Beneficial / Positive	Harmful / Negative
Underlying Expectation	Positive anticipation of healing	Negative expectation of harm or side effects
Psychological Mechanism	Expectancy, Conditioning, Reduced Anxiety	Anticipation of pain, Anxiety, Conditioned fear
Neurobiological Changes	Release of endorphins, dopamine	Release of cholecystokinin, stress activation
Associated Effect	Reduction of symptoms (pain, nausea)	Worsening of symptoms, increased side effects
Ethical Considerations	Complex; often involves deception unless openly disclosed	Often unintended; can arise from disclosing side effects

Conclusion

When you ask, 'What do you call medicine that doesn't do anything?', the term is a placebo. However, simply calling it 'fake' overlooks its intricate role in medicine. The placebo effect highlights the powerful mind-body connection that can induce real physiological changes. Conversely, the nocebo effect demonstrates the negative impact of expectations on health. While ethical concerns limit the use of placebos in standard practice, they are crucial in clinical research for validating new treatments. Future research into open-label placebos may offer ethical ways to utilize the mind-body connection therapeutically.

For more information on the ethical guidelines for using placebos in clinical practice and research, see the American Medical Association's Code of Medical Ethics at ama-assn.org.

Frequently Asked Questions

The primary purpose is to act as a control. By comparing the results of a group receiving the experimental treatment to a group receiving a placebo, researchers can accurately determine the true effectiveness of the new treatment.

Yes, a placebo can cause real, measurable improvements in symptoms, particularly those related to pain, anxiety, and depression. This happens because the brain's expectation of relief can trigger the release of its own powerful neurochemicals, such as endorphins.

A placebo is a substance given to intentionally produce no direct therapeutic effect, often as a research control. An inactive ingredient is a functional component of a real medicine, like a filler or binder, and is not a placebo.

Generally, most modern medical guidelines, including those from the AMA, consider it unethical to deceive a patient with a placebo in clinical practice. The patient must be informed and consent to the use of a placebo for it to be ethical.

The nocebo effect can be minimized through careful, reassuring communication during consultations and through specific phrasing of side effect information, focusing on the positive likelihood of having no side effects.

'Open-label' placebos are inert treatments where the patient is openly told they are receiving a placebo. Research shows that even with this knowledge, patients can still experience a beneficial placebo effect.

No. The placebo effect does not imply an imaginary illness. It shows that the mind can influence the body in a way that produces real physical changes and symptom relief, particularly for conditions influenced by psychological factors like stress.