The science of placebo

Let’s start with something strange. A person takes a pill with no medicine in it, just sugar. Within minutes, their headache fades. Another drinks tap water, believing it came from a holy spring. They feel peaceful, hopeful, emotionally lifted. What’s going on here? Welcome to the world of the placebo effect, where belief triggers biology and healing begins not with chemicals, but with meaning. It’s also where your brain becomes your own pharmacist and doesn’t charge a consultation fee.
This isn’t a trick. It’s a real mind, body response that neuroscience takes seriously. When people expect treatment to work, the brain activates areas like the rostral anterior cingulate cortex and cerebellum; and releases dopamine, serotonin and endorphins. Parkinson’s patients have even shown improved motor control just by believing they were treated. The prefrontal cortex lights up too. Belief, it turns out, is chemistry. A review of 186 clinical trials involving over 16,000 patients found that about 54 per cent of the treatment effect came from the placebo or context, not the actual drug. In antidepressant trials, placebos have become so effective that real medicines often struggle to outperform them.
Hope and optimism do plenty. People who believe they will get better often do. Reviews show traits like confidence, plus how doctors or media frame information, can boost placebo responses. Faith brings something extra. In Lourdes, France, people given plain water labelled as “Lourdes water” felt calmer and showed brain changes. In another study, people who drank “prayer-infused water” reported better moods than those who didn’t know the water had spiritual meaning. One experiment found that Catholics looking at an image of the Virgin Mary during a fake treatment reported less pain, with brain activity showing signs of compassion and relief.
It’s not just what is given, but how. Patients improve when they trust their doctor, feel heard and sense warmth. Even the colour of the pill can matter. These subtle cues are part of the “contextual effect”, which shapes how the body responds. Doctors understand this well. Many admit to prescribing vitamins or mild remedies to meet patient expectations. Often, the patient feels better because the care experience itself sparks recovery. The wellness world knows this too; detox teas, essential oils and meditation apps thrive on belief and ritual.
One of the strangest findings is that patients don’t even need to be fooled. In “open-label placebo” studies, people are told, “This is a placebo” and they still improve. Harvard researchers have shown this in conditions like IBS, hot flashes, depression and chronic pain. A 2025 Washington Post story described back pain patients who felt lasting relief after knowingly taking sugar pills, helped by doctors who were open and kind. Wired noted in 2024 that even when we know it’s all “theatre”, the ritual can still work.
Placebo effects have even appeared in babies, animals and unconscious patients. When caregivers believe treatment will work, they act more positively, and that seems to help. Even sham surgeries, where nothing is actually done, can lead to real relief. A 2025 review titled “Justice for Placebo” suggests we stop seeing placebo as deception and start using it ethically, especially for chronic pain and mental health. The future might even include personalised placebo strategies that combine medicine with meaning.
All of this leads to one simple truth. Belief, trust and care are not extras. They are part of the cure. Whether it’s a sugar pill, a kind word, or a confident smile, the thing that heals might not be the substance; it might be everything around it. And no, that’s not a scam. That’s medicine with a human face. Belief might just be the oldest, safest medicine we have. And yes, one of its side effects may include unexpected hope.

Dr Khalfan al Harrasi The author is an academic and researcher