There is evidence that stimulants such as alcohol and tobacco have an effect on the immune system, but little is known about how these lifestyle factors affect the prevalence of contact sensitization. This study investigated whether smoking and alcohol consumption were associated with contact sensitization and nickel sensitization. A random sample of adults (n=3460) from the general population of Copenhagen was invited to participate in a general health examination including patch-testing. Alcohol consumption was not associated with nickel sensitization, whereas a significant trend (p