acetylcholine receptors to release neurotransmitters such as dopamine, glutamate, and gamma-aminobutyric acid.: 2296 cessation of smoking leads to symptoms of nicotine withdrawal such as anxiety and irritability.: 2298 professional smoking cessation support methods generally endeavour to address both nicotine addiction and nicotine withdrawal symptoms. smoking cessation can be achieved with or without assistance from healthcare professionals or the use of medications. methods that have been found to be effective include interventions directed at or through health care providers and health care systems; medications including nicotine replacement therapy (nrt) and varenicline; individual and group counselling; and web-based or stand-alone computer programs. although stopping smoking can cause short-term side effects such as reversible weight gain, smoking cessation services and activities are cost-effective because of the positive health benefits. at the university of buffalo, researchers found out that fruit and vegetable consumption can help a smoker cut down or even quit smoking a growing number of countries have more ex-smokers than smokers. early "failure" is a normal part of trying to stop, and more than one attempt at stopping smoking prior to longer-term success is common. nrt, other prescribed pharmaceuticals, and professional counselling or support also help many smokers. however, up to three-quarters of ex-smokers report having quit without assistance ("cold turkey" or cut down then quit), and cessation without professional support or medication may be the most common method used by ex-smokers. the number of nicotinic receptors in the brain returns to the level of a nonsmoker between 6 and 12 weeks after quitting. in 2019, the fda authorized the selling of low-nicotine cigarettes in hopes of lowering the number of people addicted to nicotine.