Caffeine Withdrawal Is More Common Than You Think. Why Experts Are Using Placebo Effect to Study Symptoms
If you’ve ever tried to cut back on coffee and felt the dreaded headache, fog and fatigue set in, there may be a surprisingly simple workaround sitting on the grocery shelf. New research suggests that a cup of decaf, yes, even when you know it’s decaf, can ease caffeine withdrawal symptoms in habitual coffee drinkers. The findings point to the powerful role expectation and habit play in how our bodies experience dependence.
A 2023 study published in the Journal of Psychopharmacology examined 61 heavy coffee drinkers, people accustomed to three or more cups a day, after they went 24 hours without caffeine. The results offer fresh insight into why caffeine withdrawal hits so hard and what might help people ride it out.
What the Study Found About Caffeine Withdrawal and Decaf
Researchers at the University of Sydney designed the study to test how belief and biology interact during caffeine withdrawal. Participants first rated the severity of their symptoms and predicted how much relief they’d get from caffeinated coffee, decaf or water. They were then split into three groups. One received decaf but was told it was regular coffee (the deceptive group), one received decaf and was told it was decaf (the open-label group) and a control group received water labeled as water. After 45 minutes, everyone rated their symptoms again.
“A convincing cup of decaf has the power to reduce withdrawal symptoms a lot when the person drinking it is unaware it’s decaf. But our study suggests that even if they are aware it’s decaf, their withdrawal still subsides,” Dr. Llew Mills, a senior research associate at the School of Addiction Medicine, said, per The University of Sydney.
The deceptive group reported the biggest drop in symptoms, a classic placebo response. But the group that knowingly drank decaf also experienced significant relief, while the water group saw essentially no change.
How the Open-Label Placebo Effect Works
The phenomenon at the heart of the study is called the open-label placebo effect, when people experience real benefits from a treatment even though they know it contains no active ingredient. It’s a finding that has shown up in multiple studies, and Mills says caffeine withdrawal is a striking example.
“The group we lied to reported a big drop in caffeine withdrawal even though there’s no pharmacological reason why it should. Because they expected their withdrawal to go down, it did go down,” Mills said. “In other words, a placebo effect. We’ve found this in several studies now.”
What surprised researchers was the open-label result. “What was interesting in this new study is that withdrawal symptoms also reduced even when people knew they were getting decaf. Not as much as the group we lied to, but a significant amount,” Mills said.
The study concluded that “open-label placebo caffeine (i.e. decaf) can reduce caffeine withdrawal symptoms, even when people do not hold a conscious expectancy it will do so,” adding that “there may be ways to integrate open-label placebo procedures into clinical interventions for drug dependence without violating informed consent.”
Why Expectations Didn’t Match the Results
Before drinking anything, participants predicted how much relief each beverage would provide. Caffeinated coffee was, as you’d guess, the runaway favorite. But the rest of the predictions told a more curious story.
“Funnily enough, they actually expected water to reduce their withdrawal more than decaf,” Mills said. “Withdrawal in the group we gave water to didn’t drop at all, whereas the people who were given decaf experienced a significant reduction. The reduction they experienced was contrary to what they expected would happen when they were given water and decaf.”
In other words, the decaf worked better than people thought it would, and water didn’t work at all, despite expectations to the contrary.
Why a Learned Response May Explain the Relief
Mills and his team suggest the open-label placebo effect may be rooted in years of conditioning. They propose that the lift people feel from their morning cup isn’t just caffeine kicking in. It’s the relief of withdrawal symptoms that had built up overnight. Over time, the taste and smell of coffee become tied to that relief, so much so that decaf can trigger a similar conditioned response even without any caffeine in the cup.
Still, Mills cautioned that the effect is likely temporary. Decaf shouldn’t be expected to relieve withdrawal symptoms on an ongoing basis, but it could be a useful short-term tool.
“But a cup of decaf could help someone who is trying to cut back their caffeine intake to temporarily ride out the worst of the cravings and help them stay caffeine-free,” he said.
What This Means for Cutting Back on Caffeine
The takeaway for anyone trying to wean off coffee is practical. Reaching for a decaf during the rough early days of a caffeine reset may genuinely help, even if you know exactly what’s in the mug. The ritual itself, the warmth, the aroma, the familiar routine, appears to do real work in calming withdrawal.
“This study shows cognitive factors like what you expect, and how much of a drug you think you have in your body, have a big effect on how you experience withdrawal symptoms,” Mills said.
The research also points beyond coffee. Mills said the team designed the study to model processes that show up in addiction more broadly.
“We did this study to model some of the processes involved in addiction to any drug, including more serious, or harmful, drugs,” he said. “What we found has some promise for developing new treatments for addiction that integrate placebo effects.”
This article was created by content specialists using various tools, including AI.
This story was originally published June 12, 2026 at 11:00 AM with the headline "Caffeine Withdrawal Is More Common Than You Think. Why Experts Are Using Placebo Effect to Study Symptoms."
