Objective: To review the pharmacology, therapeutics, adverse effects, and societal implications of the medical use of marijuana.
Data sources: MEDLINE and manual searches of English-language marijuana literature, supplemented with interviews of scientists currently conducting cannabinoid research. Search terms included pain OR palliative care AND cannabis or ALL marijuana; cachexia OR appetite OR appetite stimulants; muscle spasticity OR spasm; immune system and cannabis; nausea and vomiting and cancer and cannabis. MEDLINE search terms: cannabis OR marijuana smoking OR marijuana abuse; all glaucoma; multiple sclerosis AND cannabis OR marijuana smoking OR marijuana abuse.
Study selection: Studies on pharmacology, risks, and medical potential of marijuana.
Data extraction: Not applicable.
Data synthesis: The most prominent effects of marijuana are mediated by receptors in the brain. Acute intoxication is characterized by euphoria, loss of short-term memory, stimulation of the senses, and impaired linear thinking. Depersonalization and panic attacks are adverse effects. Increased heart rate and reddened conjunctivae are common physical effects. Chronic, high doses may cause subtle impairment of cognitive abilities that are appear to be long-term, but of unknown duration. Marijuana may be a risk factor for individuals with underlying mental illness. It causes dependence, but compared with cocaine, alcohol, heroin, and nicotine, marijuana has little addictive power and produces only mild withdrawal symptoms. Marijuana shows clinical promise for glaucoma, nausea and vomiting, analgesia, spasticity, multiple sclerosis, and AIDS wasting syndrome.
Conclusion: As a recreational drug, marijuana poses dangers, particularly to social and emotional development during adolescence and young adulthood. As a medical drug, marijuana should be available for patients who do not adequately respond to currently available therapies.