Got the flu? Why a fake treatment might be your cure … and which ones to avoid

A few months ago, on a long-haul flight at the start of a long-awaited trip to Europe, disaster struck: I caught the flu. My unwelcome new travel companion and I arrived at my friend’s doorstep in Germany – sneezing, bone-tired and ready to throw in the towel. But my friend had a plan: a megadose of vitamin C, as recommended by two-time Nobel Prize laureate Linus Pauling. I took it, and within days I was back on my feet. What could have ruined the trip became a brief hiccup. Did the vitamin C work? Maybe. But having spent years researching the placebo effect, I suspected there was something else at play.

Now that cold and flu season is here again, many of us are reaching for familiar remedies: lemon and honey tea, eucalyptus rubs, chicken soup, vitamin C. Maybe we don’t expect them to cure us, but we do expect to feel better. And often, we do. That expectation is shaped by powerful subconscious forces – experiences, beliefs, memory and culture – that science shows can produce real effects. Placebo science is evolving rapidly, revealing how these forces work and how they’re being amplified in our digital age.

The modern study of placebo effects began in the 1950s, when American anaesthetist Henry Beecher observed that wounded soldiers often reported pain relief after being given saline – believing it was morphine. His landmark paper, The Powerful Placebo, suggested that belief alone could trigger genuine physiological responses.

Since then, research has shown that expectations, context, and meaning can shape how we perceive symptoms and how our bodies respond. In the context of colds and flu, placebo effects can reduce symptoms like fatigue, cough, pain and headache. And while placebos don’t directly eliminate viruses, symptom relief can have downstream effects – better rest, reduced stress and improved mood – which may, in turn, support immune recovery, reduced illness severity and faster healing. When we take a home remedy, we’re not just ingesting “active ingredients” – we’re engaging powerful mind-body responses shaped by habit, memory and social learning. These aren’t imagined – they’re real biological responses, suggesting that mind and body are more connected than we once thought.

Vaccines, interestingly, operate in a different realm. Because they prevent illness rather than treat symptoms, they don’t tend to trigger placebo effects. In fact, they’re more associated with nocebo effects, where negative expectations cause real but non-specific symptoms such as headache or fatigue. An influential meta-analysis (a high-quality study that combines data from many trials to reveal overall patterns) of COVID-19 vaccine studies found that up to 76 per cent of systemic side effects, like headache and fatigue, were likely due to nocebo effects – not the vaccine itself – based on similar reports in placebo groups. Similar effects have been observed with flu vaccines. These negative symptoms aren’t imagined either, but they are also shaped in part by expectation. But when symptoms are caused by nocebo effects rather than the vaccine itself, they can become powerful stories that influence vaccine hesitancy and public discourse, even amid overwhelming scientific evidence for vaccine safety and effectiveness.

If you’re now feeling a little more pro-placebo, great – they’re powerful allies. But in the age of social media, that same power can be shaped, and sometimes distorted, by the platforms we use.

If you’re thinking your home remedy won’t work because you know it’s a placebo, think again. Open-label placebo studies – where people knowingly take an inert treatment – have shown surprisingly strong results. People with pain, fatigue, and irritable bowel syndrome have found relief despite knowing the treatment was inert. The key is allowing people to value the ritual of treatment as much as the substance. In this way, many home remedies function as open-label cultural placebos. We may not believe they’ll cure anything, but they give us hope and belief, which studies show leads to improvements in symptoms anyway.

If you’re now feeling a little more pro-placebo, great – they’re powerful allies. But in the age of social media, that same power can be shaped, and sometimes distorted, by the platforms we use. It is well known that the placebo effect is stronger when treatment is recommended by an authority figure or trusted expert. In my case, my friend’s firm belief – backed by Pauling’s scientific cred – likely shaped my response. Now, social media influencers sharing health hacks can, unfortunately, act as powerful placebo catalysts. When an influencer swears a remedy cured their flu, pain or chronic condition, their message – liked, shared and algorithmically boosted – shapes expectations at scale. The algorithms themselves tend to show us more of what we already believe, reinforcing the illusion of consensus. Social media doesn’t just spread health trends – it amplifies placebo effects in ways we’re only beginning to understand.