Medical cannabis has several potential beneficial effects. Evidence is moderate that it helps in chronic pain and muscle spasms. Low quality evidence suggests its use for reducing nausea during chemotherapy, improving appetite in HIV/AIDS, improving sleep, and improving tics in Tourette syndrome. When usual treatments are ineffective, cannabinoids have also been recommended for anorexia, arthritis, migraine, and glaucoma.
It is recommended that cannabis use be stopped in pregnancy.
Nausea and vomiting
Medical cannabis is somewhat effective in chemotherapy-induced nausea and vomiting (CINV) and may be a reasonable option in those who do not improve following preferential treatment. Comparative studies have found cannabinoids to be more effective than some conventional antiemetics such as prochlorperazine, promethazine, and metoclopramide in controlling CINV,but these are used less frequently because of side effects including dizziness, dysphoria, and hallucinations. Long-term cannabis use may cause nausea and vomiting, a condition known as cannabinoid hyperemesis syndrome.
A 2016 Cochrane review said that cannabinoids were "probably effective" in treating chemotherapy-induced nausea in children, but with a high side effect profile (mainly drowsiness, dizziness, altered moods, and increased appetite). Less common side effects were "occular problems, orthostatic hypotension, muscle twitching, pruritis, vagueness, hallucinations, lightheadedness and dry mouth".
Evidence is lacking for both efficacy and safety of cannabis and cannabinoids in treating patients with HIV/AIDS or for anorexia associated with AIDS. As of 2013, current studies suffer from effects of bias, small sample size, and lack of long-term data.
Tentative evidence suggests cannabis maybe useful for neuropathy but evidence of benefit is lacking for other types of long term pain. A 2009 review states it was unclear if the benefits were greater than the risks, while a 2011 review considered it generally safe for this use. In palliative care the use appears safer than that of opioids. A 2014 review found limited and weak evidence that smoked cannabis was effective for chronic non-cancer pain. The review recommended that it be used for people for whom cannabinoids and other analgesics were not effective. A 2015 review found moderate quality evidence that cannabinoids were effective for chronic pain. A 2015 meta-analysis found that inhaled medical cannabis was effective in reducing neuropathic pain in the short term for one in five to six patients. Another 2015 systematic review and meta-analysis found limited evidence that medical cannabis was effective for neuropathic pain when combined with traditional analgesics.
The efficacy of cannabis in treating neurological problems, including multiple sclerosis (MS), epilepsy, and movement problems, is not clear. Studies of the efficacy of cannabis for treating multiple sclerosis have produced varying results. The combination of Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD) extracts give subjective relief of spasticity, though objective post-treatment assessments do not reveal significant changes. Evidence also suggests that oral cannabis extract is effective for reducing patient-centered measures of spasticity. A trial of cannabis is deemed to be a reasonable option if other treatments have not been effective.Its use for MS is approved in ten countries. A 2012 review found no problems with tolerance, abuse or addiction.
Posttraumatic stress disorder