Reducing hot flashes during prostate cancer treatment

For many men undergoing treatment for prostate cancer, hot flashes can be an unexpected and even disruptive part of androgen-deprivation therapy (ADT). ADT lowers male hormones like testosterone, which prostate cancer cells rely on to grow. By reducing testosterone levels, ADT helps slow or control the cancer.

What are the side effects of ADT?

Testosterone affects many systems in the body. When levels drop, side effects can occur.

Common side effects of ADT include:

• Hot flashes
• Fatigue
• Sleep disturbances
• Mood changes
• Decreased libido
• Loss of muscle mass
• Weight gain
• Bone thinning

Hot flashes are particularly common, affecting up to 80% of men on ADT. They can feel like sudden waves of heat, sweating, flushing, and sometimes chills afterward. Over time, they may interfere with sleep, worsen fatigue, and reduce overall quality of life. For some men, the symptoms become so severe that they consider stopping treatment, making symptom management especially important.

A possible new way to manage hot flashes

Researchers recently studied whether oxybutynin could help reduce hot flashes in men receiving ADT.

In a Phase II clinical trial, participants were randomly assigned to receive either oxybutynin 2.5mg twice daily, oxybutynin 5mg twice daily, or a placebo for six weeks. 

The results revealed that men taking oxybutynin experienced significantly greater improvements than those taking placebo. On average:

• Men in the placebo group had 2.15 fewer hot flashes per day and a 4.85-point drop in daily severity scores.
• Men taking 2.5mg twice daily had 4.77 fewer hot flashes per day and a 9.94-point reduction in severity.
• Men taking 5mg twice daily experienced the greatest benefit, with 6.89 fewer hot flashes per day and a 13.95-point reduction in severity.

Nearly 80% of men in the higher-dose group achieved at least a 50% reduction in their hot flash scores, compared with 32% of those taking a placebo. Improvements often began within the first week and were sustained throughout the six-week study period.

What about side effects?

Overall, oxybutynin was well tolerated. The most commonly reported side effect was dry mouth. No major safety concerns were identified during the study.

Why this matters

Oxybutynin has been shown to reduce hot flashes in women, but this study marks the first randomized trial examining the efficacy of the drug in men. While researchers are optimistic about these early findings, larger studies are needed to fine-tune the dosage.  

Hot flashes may not be life-threatening, but they can significantly disrupt daily life. If you’re experiencing hot flashes during prostate cancer treatment, talk with your care team. There may be options from medications and lifestyle adjustments that can help reduce symptoms and make treatment more manageable.

You don’t have to manage your ADT side effects alone. Join our Outcomes4Me Community to meet and connect with other people with prostate cancer today.