Urinary incontinence is defined as a loss of bladder control. Incontinence can result from several biological factors, including weak bladder muscles and inflammation, as well as from nerve damage associated with diseases such as multiple sclerosis (MS) and Parkinson’s disease. More than one in ten Americans over age 65 is estimated to suffer from incontinence, particularly women.
Several clinical trials show that the administration of cannabis-derived extracts improves bladder control. For example, investigators at Oxford’s Centre for Enablement in Britain reported that self-administered doses of whole-plant cannabinoid extracts improved incontinence compared to placebo in patients suffering from MS and spinal cord injury. In a follow up study of 15 patients with advanced multiple sclerosis, investigators at London's Institute for Neurology reported that cannabis extract therapy significantly decreased urinary urgency, frequency, and nocturia (urination at night). They concluded, "Cannabis-based medicinal extracts are a safe and effective treatment for urinary and other problems in patients with advanced MS."
These findings were replicated in a multi-center, randomized placebo-controlled trial involving 630 patients. Researchers reported that subjects administered cannabis extracts experienced a 38 percent reduction in incontinence episodes from baseline to the end of treatment, while patients administered THC alone experienced a 33 percent reduction, suggesting a "clinical effect of cannabis on incontinence episodes." Extracts have also been shown to reduce overactive bladder symptoms in subjects with previously treatment resistant OAB.
In light of these clinical trial findings, some experts have recommended the use of cannabinoids as potential 'second-line' agents for treating incontinence. However, similar trials assessing the use of whole-plant cannabis on bladder control have yet to be conducted.
 Wade et al. 2003. A preliminary controlled study to determine whether whole-plant cannabis extracts can improve intractable neurogenic symptoms. Clinical Rehabilitation 17: 21-29.
 Brady et al. 2004. An open label pilot study of cannabis-based extracts for bladder dysfunction in advanced multiple sclerosis. Multiple Sclerosis 10: 425-433.
 Freeman et al. 2006. The effect of cannabis on urge incontinence in patients with multiple sclerosis: a multicentre, randomized placebo-controlled trial. The International Urogynecology Journal 17: 636-641.
 Teresa-Maniscalco et al. 2017. THC/CBD oromucosal spray in patients with multiple sclerosis overactive bladder: a pilot prospective study. Neurological Sciences [online ahead of print]
 Kalsi and Fowler. 2005. Therapy insight: bladder dysfunction associated with multiple sclerosis. Nature Clinical Practice Neurology 2: 492-501.