Aims To describe the prevalence and intensity of different symptoms in relation to tobacco abstinence. To explore latent dimensions between symptoms in smokers trying to quit.

Design A cross sectional study using a questionnaire to retrospectively assess symptoms over a period of 12 months.

Setting Swedish telephone quitline, a nationwide free of charge service.

Participants All 741 individuals who had called the quitline and signed up for smoking cessation treatment between February 2000 to November 2001 and reported to have been smoke free for at least 24 hours during the previous 12 month period from first contact.

Measurements Assessments were made by self-report, and abstinence was defined as "not a single puff of smoke during the last week". A factor analysis approach where individual items aggregate into factors was used to explore the relationship between the different symptoms.

Findings High intensity of symptoms related to unsuccessful quitting attempts and included craving, irritability, apprehension/anxiety, difficulties concentrating, restlessness, depression/depressed mood, and insomnia. The factor loadings of all 17 symptoms resulted in three factors with factor 1, psychological being the most important. High scores on this factor relates to unsuccessful quitting attempts. Using Nicotine Replacement Therapy (NRT) for 5 weeks or longer, reduced symptoms included in factor 1. The other two factors were factor 2 physiological and factor 3 neurological.

Conclusion Symptoms that are psychological and/or neurological in nature are interrelated and appear to be the most significant obstacles for successful quitting attempts in a population-based setting. These symptoms may be successfully treated with NRT.