Cannabis has many health benefits, as tolerated by individual patients. Benefits include: decreased chronic inflammation (psoriasis/arthritis/eczema/multiple sclerosis/parkinsons), increased immune function, decreased pain (including nerve pain), decreased depression, anxiety, insomnia, etc.
There are risks to include: abuse and addiction, impaired driving; a correlation with cannabis use and low birth weights and developmental delays in pregnancy.
Short term side effects are decreased memory, attention, reaction time, productive cough, heart palpitations or change in blood pressure; numbness or muscle twitching.
Long term side effects are decreased ability to learn new information specifically noted in <25 year olds, due to their brains not being fully developed. This has been studied to decrease a child’s IQ by a few points.