One cigarette a day should not cause any immediate visible problems but over time it probably will. I would suggest you try another relaxing methods, as I do not think smoking is a good method to release stress – try something more healthy. How about sport or yoga? They are great for stress and healthy!

“In another study, published in 2007 in the Journal of the European Academy of Dermatology and Venereology, researchers reported that of the 594 participants studied, ‘In girls, smoking was significantly associated with lower prevalence of acne…No significant associations between acne and smoking variables were detected among boys.’ A study published in the British Journal of Dermatology in 2001 seems to refute these findings. 896 people were examined for the study. Smokers tended to have more acne, and the more they smoked, the worse their acne presented itself. Other studies have showed no statistical difference between smokers and non-smokers in regards to acne. In short, evidence is conflicting and the medical research community needs quite a bit more data to come to a consensus.”

http://www.acne.org/smoking-and-acne.html