Washington: The Ohio state in the US has legalised marijuana use for medical purposes, the 26th state in the nation to do so, a media report said. Ohio Governor and former Republican Party presidential hopeful John Kasich on Wednesday signed the legalisation bill into law, Politico reported. Kasich has said he would like children with certain medical conditions to be able to relieve their pain through cannabis use. The state legislature approved the plan in May. It will go into effect in three months. The patients will need a physician's recommendation to legally use the drug. At first, they will have to buy from other states where it is legal until commercial cultivators have time to set up and grow the weed in Ohio. Only vaporisers, edibles, and oils are allowed -- smoking marijuana is still illegal. Only people with certain conditions, like AIDS, cancer, PTSD, and epilepsy, can qualify for the use.