In simple terms, It is dangerous to purchase any form of prescription online especially when you do not know the source of the medicine. Most online pharmacies are unregistered and some of their medication come from unknown source hence if you want to purchase online, make sure that online pharmacies have a legal prescription and are registered. You can know it if you make research about the pharmacy and see if they are registered by the government make sure to check the validity of their offerings before purchasing from them.