A medical device is configured to deliver a first stimulation therapy to a patient, and, upon detecting a trigger event, deliver a second stimulation therapy to the patient. In some examples, the first stimulation therapy includes bilateral stimulation in which stimulation is delivered at different times to two lateral sides of the patient and the second stimulation therapy includes substantially simultaneous bilateral stimulation therapy to two lateral sides of the patient. In some examples, the second stimulation therapy may elicit a stronger inhibitory physiological response related to incontinence (e.g., inhibition of bladder contractions) than the first stimulation therapy. The trigger event may include, for example, any one or more of detection of a physiological condition indicative of an increased possibility of an involuntary voiding event or an imminent involuntary voiding event, input from the patient, a predetermined time of day, or expiration of a timer.