戒烟是指吸烟者戒除吸用尼古丁的毒瘾，亦是目前世界各国一项主要健康议题。当人类吸入尼古丁后，会影响脑中的奖赏路径（reward pathways），使吸食者感到愉悦，不少初期吸食者均认为自己不会上瘾，约数周至数月后逐渐成瘾。跟喝酒的人不同，大部分持续抽烟者均受烟瘾影响，但经常喝酒的人之中，只有少数为酗酒者。

当成瘾者停止抽烟后，由于血压和心跳下降，身体吸氧量亦相应减低，会出现晕眩、烦躁、咳嗽、干渴、胃部不适、便秘、疲累、手脚轻微发热，此种不适反应称为「烟瘾」。如果成瘾者拒绝吸烟，让血管中尼古丁含量大减，约数日后，成瘾症状会大幅纾缓甚至消失，但不少成瘾者只要抽几口烟，数秒内亦能即时解除烟瘾，直到烟瘾在数十分钟至数小时后再次发作为止（一些吸烟新手的戒断症状可以在数日至数星期后才发作）。正因为自然调节过慢、而吸入尼古丁能即时暂解烟瘾，不少人难以停止抽烟，最终演变成恶性遁环，吸入更多的尼古丁，倚赖性更强。

Smoking cessation (colloquially quitting smoking) is the process of discontinuing tobacco smoking. Tobacco contains nicotine, which is addictive, making the process of quitting often very prolonged and difficult.

Smoking is the leading preventable cause of death worldwide, and quitting smoking significantly reduces the risk of dying from tobacco-related diseases such as heart disease and lung cancer. Seventy percent of smokers would like to quit smoking, and 50 percent report attempting to quit within the past year. Many different strategies can be used for smoking cessation, including quitting without assistance ("cold turkey" or cut down then quit), medications such as nicotine replacement therapy (NRT) or varenicline, and behavioral counseling. The majority of smokers who try to quit do so without assistance, though only 3 to 6% of quit attempts without assistance are successful. Use of medications and behavioral counseling both increase success rates, and a combination of both medication and behavioral interventions has been shown to be even more effective.