Cytisine

Cytisine is a toxic pyridine-like alkaloid. Pharmacologically it exhibits similar effects to nicotine due to structural similarity of the two molecules. In large doses it can interfere with respiration and become fatal.

Uses
Cytisine is a nicotinic acetylcholine receptor agonist, and as a pharmaceutical preparation it is available for the treatment of nicotinism. Cytisine derivative varenicline was approved in 2006 as a smoking cessation drug. A 2006 literature review concludes that while trials performed with cytisine itself are mostly of poor quality, there is some evidence that cytisine may be prescribed to aid in smoking cessation.

Plants containing cytisine, including the Common Broom and Mescalbean have also been used recreationally. Positive effects are reported to include a mild intoxication and heightened awareness of color. However this practice is not recommended since negative side-effects can include nausea, vomiting, convulsions, heart pain, headache and in larger doses even death via respiratory failure.