Relationship between smoking and erectile dysfunction.

We estimated the effects of smoking on the risk and prognosis of erectile dysfunction (ED), and of ED on smoking behavior. The follow-up sample consisted of the 1442 men aged 50-75 y, who responded to both baseline and follow-up questionnaires. We estimated the effect of smoking on the incidence of ED among the 1130 men free from ED, ED on risk to start smoking in the 502 nonsmokers, smoking on the prognosis of ED among the 312 with ED and ED on quitting smoking among the 292 current smokers at baseline. Risk of ED increased nonsignificantly with smoking (odds ratio (OR)=1.4), while ED recovery reduced (OR=0.6). Therefore, there was the ratio of 2.3 (1.4/0.6) describing the total effect of smoking on the risk of ED. Both quitting (OR=1.7) and starting (OR=1.9) smoking were rare and nonsignificantly higher in men with ED. Most of the OR estimates on smoking-ED relationships were not statistically significant, probably due to small numbers. There are two bidirectional relations between ED and smoking. Those who smoked had a higher risk of ED than nonsmokers. The men with ED were more likely to start smoking than those free from ED. The estimates of effects were not statistically significant, but they were consistent with each other and with the hypothesis that smoking causes ED and ED causes smoking. The recovery from ED was less in smokers than among nonsmokers, and current smokers with ED were more likely to stop smoking than men free from ED. Numbers were few and estimates of effects were not significant, but consistent with the hypothesis of smoking preventing recovery from ED and ED improving the success of smoking cessation. Such transitions in four directions explain indirectly the known positive association between the prevalence of smoking and the prevalence of ED.