“There are records of the cannabis plant being used for medicinal purposes in ancient times, and in the 19th century it was used as an effective anti-epileptic drug (AED) in children.
However, because of its abuse potential, most countries imposed laws restricting its cultivation and use, and this has greatly inhibited research into possible therapeutic uses.
Things are now changing, and cannabis derivatives are now used legally to treat, for example, pain, nausea and spasticity.
The plant contains over 100 biologically active compounds, and recently it has been possible to isolate these and identify the neurochemical mechanisms by which some of them operate: one in particular, cannabidiol”
https://www.ncbi.nlm.nih.gov/pubmed/29449212
http://adc.bmj.com/content/early/2018/02/15/archdischild-2018-314921