Oxybutynin is an anticholinergic medication used to relieve urinary and bladder difficulties, including frequent urination and inability to control urination (urge incontinence), by decreasing muscle spasms of the bladder. It competitively antagonizes the M1, M2, and M3 subtypes of the muscarinic acetylcholine receptor. It also has direct spasmolytic effects on bladder smooth muscle as a calcium antagonist and local anesthetic, but at concentrations far above those used clinically. It is available orally in generic formulation and as the brand-names Ditropan and Lyrinel XL, and as a transdermal patch under the brand-name Oxytrol.

Oxybutynin also shows promise for treatment of hyperhidrosis, or hyper-active sweating.

Oxybutynin contains one stereocenter. Commercial formulations are sold as the racemate. The (R-)enantiomer is a more potent anticholinergic than either the racemate or the (S-)enantiomer, which is essentially without anticholinergic activity at the doses used in clinical practice. However, (R)-oxybutynin administered alone offers little or no clinical benefit above and beyond the racemic mixture. The other actions (calcium antagonism, local anesthesia) of oxybutynin are not stereospecific. (S)-oxybutynin has not been clinically tested for its spasmolytic effects, but may be clinically useful for the same indications as the racemate, without the unpleasant anticholinergic side effects.