Bupropion (Zyban) - Availability of Zyban may vary regionally

Bupropion (brand name Zyban) is a medicine originally used to treat depression, but it has since been found to help people quit smoking.

It's not clear exactly how it works, but it's thought to have an effect on the parts of the brain involved in addictive behaviour. 

For more information: supporting information.

Varenicline - Availability of Varenicline may vary regionally

Varenicline works by reducing symptoms of withdrawal and blocking some of the 'rewarding' effects of smoking, making quitting easier and relapse less likely. 

For more information: supporting information. 

Cytisinicline (Cytisine) - Availability of Cytisine may vary regionally