Hi My Friend Was Diagnosed With An Extremely Rare Case

hi my friend was diagnosed with an extremely rare case of TB in Feb this year. Hes on a 6 month treatment and hes having his last check up this month. The past month he's been smoking weed now and again. Will this make him worse? I know weed is a drug and your not supposed to take drugs but he chooses to smoke so just wondering if it will slow down his recovery or anything?