Why nicotine (skin) patches itch?

Until now, itching caused by applying nicotine as a part of nicotine replacement therapy was attributed to "activation of nicotinic acetylcholine receptors in chemosensory neurons".


However, new research by Karel Talavera of the Leuven Catholic University in Belgium found that "the chemosensory cation channel transient receptor potential A1 (TRPA1) is crucially involved in nicotine-induced irritation".


This finding could lead to the advance of smoking cessation therapies with fewer 'itchy' effects.