How effective are medications and e-cigarettes for quitting smoking, and what works best?

Some medicines and e-cigarettes (handheld devices that work by heating liquid that usually contains nicotine and flavourings) can help people to quit smoking for six months or longer. E-cigarettes, and the medicines cytisine (otherwise known as Tabex) and varenicline (otherwise known as Chantix and Champix), appear to help the most people to quit smoking, followed by using two types of nicotine replacement therapy at once (nicotine patch and another type, such as gum or lozenge).We need more evidence on possible long-term harms of e-cigarettes and medicines to help people quit smoking, but there were very low numbers of serious harms found.