The five prescription drugs used to treat overactive bladder are only modestly effective and have side effects that can limit their usefulness. Overactive bladder is characterized by the strong urge to urinate, often frequently and sometimes accompanied by leakage.

People with only mild symptoms should try non-drug measures first, such as lifestyle changes and learning Kegel exercises to strengthen pelvic muscles.

People with more severe symptoms also benefit from such measures but may get added symptom relief from taking a medicine. The drugs work better in tandem with non-drug measures than on their own.

None of the five drugs - oxybutynin (Ditropan, Ditropan XL and Oxytrol, a skin patch); tolterodine (Detrol, Detrol LA); trospium (Sanctura); solifenacin (Vesicare); and darifenacin (Enablex) – is any more effective than the others. However, they differ is the side effects they cause and their cost. Side effects include dry mouth, constipation, and mental confusion.

In studies, Ditropan XL, Detrol LA, Oxytrol, Sanctura, Vesicare, and Enablex have caused fewer side effects.   Taking effectiveness, side effects, safety, dosing convenience, and cost into account, we have chosen the following as Consumer Reports Best Buy Drugs to treat overactive bladder – if your doctor and you have concluded a drug is worth trying:

• Tolterodine (Detrol) – two pills per day
• Tolterodine extended release (Detrol LA) – one pill per day
• Trospium (Santura) – one pill per day
• Oxybutynin patch (Oxytrol) – two patches per week

All these medicines cost quite a bit more than generic oxybutynin, the only generic now available to treat overactive bladder. Their choice as Best Buys is justified by their lower risk of side effects. Tolterodine could soon become available as a generic drug.

Some people tolerate the side effects of generic oxybutynin well. If you have no health insurance or drug coverage, we'd advise trying that first.