The Placebo Effect: When Belief Becomes Biology

Written by Iman Yaser

Imagine being given a sugar pill and told it will relieve your headache, and it actually does. This isn’t some type of magic or deception; it’s actually a fascinating, scientific phenomenon known as the placebo effect. For decades, researchers have studied how belief can cause real, measurable changes in the body; revealing the powerful connection between the mind and physical health.^1,2 The placebo effect occurs when a person experiences an improvement in symptoms after receiving a treatment that has no active therapeutic ingredient, such as a sugar pill or a saline injection.¹ Surprisingly, these “inactive” treatments can potentially lead to real physiological changes, not just imagined improvements.¹

Placebos are most commonly used in clinical trials to compare new drugs with inactive controls. If the drug performs significantly better than the placebo, scientists can be confident that the effect is due to the medication, rather than psychological factors.¹ Studies repeatedly show that participants taking placebos often report meaningful improvements, from reduced pain to better sleep, despite receiving no active treatment.³ These findings reshape how scientists understand human perception, expectation and therapeutic response.²

So, how does belief in an inactive treatment produce real effects? The explanation lies in the complex brain-body communication network. When a person expects to feel better, their brain releases chemicals capable of producing that improvement.¹ For instance, during placebo-induced pain relief, the brain releases endorphins, the body’s natural painkillers.³ These molecules bind to the same receptors targeted by drugs like morphine, reducing pain perception. Brain imaging studies have also shown measurable changes in pain-processing brain regions, such as the prefrontal cortex and anterior cingulate cortex, when participants believe they’ve received pain medication.³ In Parkinson’s disease, where dopamine production is reduced, placebo treatments have triggered measurable increases in dopamine levels and temporary improvements in movement.⁴ In short, expectation can directly alter brain chemistry.⁴

But expectation isn’t the only factor at play. The placebo effect is also influenced by conditioning: the process through which the body learns associations over time. Therefore, if an individual repeatedly experiences relief after taking medication, simply performing the action of taking a pill, even an inactive one, can trigger similar responses.¹ Physical attributes of treatments matter too: the colour, size and even branding of pills influence peoples’ expectations.⁵ Research shows that red or orange pills are often perceived as stimulants, while blue pills are seen as calming.⁵ Similarly, injections and surgeries tend to produce stronger placebo responses than pills because they are perceived as more “serious” medical interventions.⁵

The relationship between patient and practitioner is another major contributor. A compassionate, confident healthcare provider who conveys empathy and reassurance can amplify placebo effects, while a rushed or indifferent one can weaken them.⁵ The tone, setting and trust embedded in clinical encounters all shape how the brain interprets and responds to treatment.⁵ This supports research showing that the placebo effect as not merely a biological event, but also a relational and contextual one. ²

On the opposite side is the nocebo effect; the harmful counterpart of the placebo effect. As positive expectations can relieve symptoms, negative expectations can intensify them.⁶ If patients are warned a treatment may cause certain side effects, they are more likely to report those symptoms, even when given a placebo.⁶ This demonstrates how fear and anxiety can influence physiology, increasing both stress hormones and pain sensitivity.⁶ Overall, both placebo and nocebo effects reveal that what we anticipate can directly shape our health outcomes.

Rather than viewing placebo responses as deception, scientists argue they highlight an underappreciated aspect of healing: the brain’s active role in recovery.^1,2 While placebos should never replace real medical treatment, understanding how they work helps clinicians design treatments that maximize both biological and psychological benefits.¹ For instance, research on “open-label” placebos, in which patients are explicitly told the pill contains no active ingredient, has shown surprising improvements.⁷ This suggests that that the ritual of taking medicine, trusting the healthcare process and engaging in treatment, can in themselves promote healing.⁷ Such findings reinforce recent literature describing placebo responses as integral to ethical, patient-centered medicine.²

Ultimately, the placebo effect demonstrates that the brain has a remarkable ability to influence bodily processes, from pain perception to immune responses.^1,3 As science continues to uncover how expectation, trust and the therapeutic environment shape biology, one message becomes clear: belief is not a substitute for medicine, but a powerful companion to it.^1,2 In a world where healthcare often feels rushed or impersonal, the placebo effect reminds us that the human elements of empathy, connection and hope remain essential components of healing.

References:

1. Benedetti F. Placebo Effects: Understanding the Mechanisms in Health and Disease. Oxford Academic. 2014;(2). doi: 10.1093/acprof:oso/9780198705086.001.0001

2. Tzigkounakis G, Simati K, Georgiadis K. The Placebo Effect in Medicine and Clinical Practice: A Narrative Review. Cureus. 2025;17(9):e91893. doi: 10.7759/cureus.91893

3. Wager TD, Rilling JK, Smith EE, et al. Placebo-Induced Changes in FMRI in the Anticipation and Experience of Pain. Science. 2004;303(5661):1162-1167. doi: 10.1126/science.1093065

4. Lidstone SC, Schulzer M, Dinelle K, et al. Effects of Expectation on Placebo-Induced Dopamine Release in Parkinson Disease. Arch Gen Psychiatry. 2010;67(8):857-865. doi: 10.1001/archgenpsychiatry.2010.88

5. Pollo A, Amanzio M, Arslanian A, et al. Response Expectancies in Placebo Analgesia and their Clinical Relevance. Pain. 2001;93(1):77-84. doi: 10.1016/S0304-3959(01)00296-2

6. Colloca L, Miller FG. The Nocebo Effect and its Relevance for Clinical Practice. Psychosom Med. 2011;73(7):598-603. doi: 10.1097/PSY.0b013e3182294a50

Lembo A, Kelley JM, Nee J, et al. Open-Label Placebo vs Double-Blind Placebo for Irritable Bowel Syndrome: A Randomized Clinical Trial. Pain. 2021;162(9):2428-2435. doi: 10.1097/j.pain.0000000000002234