Depends a lot on how you consume it: if you smoke it, then it's more harmful than alcohol just because of the combustion phenomenon.
By other means it's true that it's less harmful than alcohol in average, but there's a big caveat for people with a psychiatric background in their family, as the risk of drug induces mental health issue (schizophrenia) can be very high in that case.
By other means it's true that it's less harmful than alcohol in average, but there's a big caveat for people with a psychiatric background in their family, as the risk of drug induces mental health issue (schizophrenia) can be very high in that case.