Oxybutynin Reduces Hot Flashes in Men With Prostate Cancer | HemOnc Today

Men undergoing treatment for prostate cancer often experience debilitating hot flashes as a side effect of androgen deprivation therapy. New research published on March 5, 2026, offers a promising solution: oxybutynin, a medication commonly used to treat overactive bladder, significantly reduces the frequency and severity of these hot flashes, and improves quality of life. The findings, presented in a randomized trial, suggest a readily available and potentially effective option for managing a common and distressing symptom for many men.

Androgen Deprivation Therapy and Hot Flashes

Androgen deprivation therapy (ADT) is a mainstay treatment for prostate cancer, working by reducing levels of testosterone, a hormone that fuels the growth of the cancer. Still, this hormonal shift often comes with significant side effects, including hot flashes experienced by 60% to 80% of men receiving ADT. Hot flashes, characterized by a sudden feeling of intense heat, sweating, and flushing, can disrupt sleep, contribute to fatigue, and negatively impact overall well-being. These symptoms can be so severe that they lead patients to discontinue potentially life-saving treatment.

Study Details and Findings

The recent study, led by Bradley J. Stish, MD, at Mayo Clinic, investigated the efficacy of oxybutynin in alleviating hot flashes among men with prostate cancer. Researchers enrolled 81 men (average age 68.5) already receiving ADT and experiencing hot flashes. Participants were randomly assigned to receive either 2.5 mg or 5 mg of oxybutynin twice daily, or a placebo. Over six weeks, participants meticulously tracked their hot flash experiences in daily diaries.

The primary endpoint of the study was the change in hot flash scores, calculated based on both the frequency and severity of hot flashes. Secondary endpoints included safety assessments, changes in hot flash frequency, and improvements in quality of life as measured by the Hot Flash-Related Daily Interference Scale (HFRDIS). The study set a statistical significance threshold of P < 0.1, acknowledging the relatively small sample size.

The results demonstrated a clear benefit from oxybutynin treatment. Men receiving 5 mg of oxybutynin twice daily experienced significantly fewer daily hot flashes compared to those receiving a placebo (a reduction of 13.95 points versus 4.85 points, P = .002). The frequency of hot flashes also decreased significantly in the 5 mg group (–6.89 vs. –2.15, P < .001). The 2.5 mg dose also showed significant improvements, though to a lesser extent.

How Oxybutynin Works – and Why It’s Not Just for Bladders

Oxybutynin’s primary use is to treat overactive bladder by blocking the action of acetylcholine, a neurotransmitter that causes bladder muscles to contract. However, research over the past decade has revealed its potential to reduce hot flashes, initially observed in women undergoing menopause or receiving breast cancer treatment. The mechanism behind this effect isn’t fully understood, but it’s believed to involve the drug’s impact on thermoregulatory centers in the brain. Dr. Stish explained that observing positive results in women prompted his team to investigate its use in men experiencing hot flashes due to ADT.

Quality of Life Improvements

Beyond reducing the physical discomfort of hot flashes, oxybutynin also led to significant improvements in quality of life. Men in the 5 mg oxybutynin arm reported less interference with their perform, social life, relationships, and overall enjoyment of life. Improvements were also noted in sleep, mood, and concentration. The 2.5 mg group experienced improvements in relationships, sexuality, and enjoyment. HFRDIS scores, which measure the impact of hot flashes on daily activities, also significantly decreased in both oxybutynin groups.

Safety and Tolerability

The study found oxybutynin to be generally well-tolerated. No grade 3 or worse adverse events were observed. The most common side effect was dry mouth, a known effect of oxybutynin, which was typically mild, and manageable. Interestingly, the 5 mg group reported improvements in blurry vision, skin rash, trouble sleeping, and urinary incontinence – effects not directly related to the drug’s intended mechanism, but potentially beneficial nonetheless.

What This Means for Patients

These findings offer a new and potentially valuable tool for managing hot flashes in men undergoing ADT for prostate cancer. Prior treatments, such as megestrol, medroxyprogesterone, and gabapentin, haven’t proven effective for all patients. Oxybutynin provides another option, particularly given its established safety profile and relatively low cost. Dr. Stish emphasized the importance of discussing hot flash symptoms with healthcare providers, as many men may be hesitant to bring them up. He noted that open communication can lead to more effective management and improved adherence to cancer treatment.

Future Research and Considerations

While the study provides encouraging results, Dr. Stish acknowledges certain limitations. The cohort was predominantly white, and further research is needed to determine if the findings apply to more diverse populations. The study did not compare oxybutynin directly to other treatments for hot flashes. Future research could explore comparative effectiveness and identify which patients might benefit most from oxybutynin. Investigating the potential of combining oxybutynin with other agents, such as fezolinetant (Veozah), which has shown promise in managing hot flashes in women, could also be beneficial.

Researchers also plan to investigate whether oxybutynin’s impact varies depending on the specific type of androgen deprivation therapy a patient is receiving. The study excluded men treated with certain androgen receptor pathway inhibitors metabolized by CYP3A4, and further investigation is needed to understand how these interactions might affect oxybutynin’s efficacy.

For more information, Bradley J. Stish, MD, can be reached at [email protected].