Dr. Shahar Madjar, Journal columnist

Matti came to see me for symptoms of overactive bladder.

“I go and go,” he tells me. “All the time. Day and night. Sometimes I don’t make it to the bathroom.”

Then he adds, “The worst is when I’m fishing.”

He describes himself and his wife in a small boat on Teal Lake. Sky above, water below. His bladder calling nonstop, demanding immediate attention.

“It’s embarrassing,” he says. “You’re surrounded by water, and yet there’s nowhere to go.”

I ask Matti if there is anything out of the ordinary he remembers from those fishing trips. He thinks for a moment, then says, “Just me and my wife. Sitting in the boat. Waiting for a fish to bite. Drinking coffee.”

Matti’s story stayed with me. Not because it was unusual, but because it was ordinary. It raised a simple question I hear often in my clinic, and not often enough in studies: could something as routine as caffeine intake be driving the urgency he described?

A systematic review published in 2023 in the International Neurourology Journal examined precisely that question. The authors asked whether modifying fluid intake and reducing caffeine consumption could meaningfully improve symptoms in adults with overactive bladder–a condition characterized by urinary urgency, frequent urination, nighttime awakenings, and sometimes incontinence, in the absence of infection or other identifiable disease.

The review analyzed eight clinical studies involving adults diagnosed with overactive bladder. Most were randomized controlled trials, the gold standard of clinical research. Rather than testing new medications or devices, these studies focused on behavioral interventions–reducing caffeine intake, adjusting total fluid consumption, or combining both approaches–and measured their effects on urgency, frequency, incontinence episodes, nocturia (nighttime frequency), and quality of life.

The most consistent finding was also the most intuitive: reducing caffeine intake improved symptoms. Across several studies, participants who consumed less caffeine experienced fewer episodes of urgency, the defining and often most distressing feature of overactive bladder. Caffeine is known to stimulate urine production and increase bladder sensitivity, and removing that stimulus appeared to calm the bladder’s exaggerated response in many patients.

Changes in total fluid intake produced less consistent results. Increasing fluid intake did not reliably improve urgency or frequency, challenging the common belief that “flushing” the bladder might be beneficial. Decreasing fluid intake sometimes reduced urinary frequency, but outcomes varied between studies. In some cases, aggressive fluid restriction risked dehydration without clear symptomatic benefit. These findings suggest that the bladder’s behavior is shaped by more than volume alone, responding instead to complex sensory and neural signals.

Caffeine reduction was also associated with modest improvements in urinary incontinence and nighttime urination. Participants who reduced caffeine tended to report fewer leakage episodes and fewer awakenings at night. Notably, combining caffeine reduction with fluid restriction did not consistently outperform caffeine reduction alone.

Several studies reported improvements in quality of life, including better sleep and reduced anxiety related to urinary symptoms. While these benefits were not universal or dramatic, they were meaningful for patients whose daily routines had been shaped around bathroom access.

The authors emphasized important limitations. The number of studies was small, study designs were heterogeneous, and adherence to lifestyle changes varied. There was insufficient uniformity to allow a formal meta-analysis. Long-term sustainability of behavioral changes also remains uncertain.

Still, the implications are significant. Fluid and caffeine modifications are low-risk, low-cost, and noninvasive interventions that can empower patients before pharmacologic therapy is considered. The review suggests that for some individuals, meaningful symptom relief may begin not with a prescription, but with attention to what–and how much–they drink.

I wanted to advise Matti to forgo coffee altogether, but two things stood in my way. First, Matti declared that coffee is an inseparable part of his Finnish heritage. A quick look at the data confirmed his statement: Finland consistently ranks as the highest consumer of coffee per capita in the world. On average, a Finnish adult consumes about 12 kilograms (roughly 26 pounds) of coffee per year, with many drinking eight or more cups a day. For Matti, giving up coffee wasn’t just a lifestyle change; it was a cultural severance.

Second, I was mindful of the broader clinical picture. While caffeine can certainly irritate the bladder, a growing body of research suggests it also offers significant protective effects for other parts of the body.

More on the surprising effects of caffeine on the body in my next article.

EDITOR’S NOTE: Shahar Madjar, MD, MBA, is a urologist and an author. He practices at Schoolcraft Memorial Hospital in Manistique and in Baraga County Memorial Hospital in L’Anse. Find his books on Amazon or contact him at smadjar@yahoo.com.