Oxybutynin, sold as under the brand names Ditropan among others, is a medication used to treat overactive bladder. It works similar to tolterodine, Darifenacin, and Solifenacin. While used for bed wetting in children, evidence to support this use is poor. It is taken by mouth or applied to the skin.

Common side effects include dry mouth, constipation, dizziness, trouble sleeping, and urinary tract infections. Serious side effects may include urinary retention and an increased risk of heat stroke. Use in pregnancy appears safe but has not been well studied while use in breastfeeding is of unclear safety. It is an antimuscarinic and works by blocking the effects of acetylcholine on smooth muscle.

Oxybutynin was approved for medical use in the United States in 1975. It is available as a generic medication. In 2020, it was the 97th most commonly prescribed medication in the United States, with more than 7 million prescriptions.