For those who consider themselves “social smokers,” partaking in an occasional cigarette during a late night of drinking with friends, the thought of lung cancer or other health consequences seem far away. They imagine that smoking diseases occur only among those grizzled 50-year-olds who’ve been smoking a pack a day for 30 years.

It turns out, however, that even the occasional cigarette can be harmful to your health over the long-term. In a new study published in Stroke, researchers examined a group of 65,521 people in Finland and found that smoking heavily as well as occasionally increased the risk of brain bleeding, or subarachnoid hemorrhage (SAH), particularly among women.

The researchers examined a population-based FINRISK study and found that 492 total people suffered from SAH over the years, 266 of whom were women. Women who had smoked over 20 cigarettes per day, considered heavy smokers, had a 3.5-times higher risk of SAH, while men had a 2.2-times higher risk. Those who smoked one to 10 cigarettes per day, meanwhile, still showed a 3-times greater risk of SAH than people who didn’t smoke.

The occasional cigarette may seem harmless, but most people don’t know what tobacco smoke consists of, according to a recent study. This suggests that casual smokers likely aren’t aware of the 4,800 different types of chemicals in cigarette smoke, including acetaldehyde and ammonia, among thousands of other toxins. Even secondhand smoke has been shown to have health risks for those bystanders who don’t inhale directly.

The casual smoker often mentions alcohol as a trigger for bumming that cigarette off a friend, noting that a good buzz is the best way to enjoy a smoke. That has to do with our brains craving the stimulant effects of nicotine after partaking in the depressant effects of alcohol, which inhibits the central nervous system. And while the number of smokers overall has decreased in the U.S. in the past several decades, light smokers seem to be among the rise, especially among women. This suggests that while most people are aware of the long-term effects of heavy smoking, many don’t realize that light smoking can have a similar impact.

There is some good news in the study, however. The authors found that people who quit smoking lowered the risk over the years. Those who had quit for over six months in particular had much lower rates of SAH than those who didn’t quit, almost to the level of non-smokers. The damage can be undone to some extent.

Source: Lindbohm J, Kaprio J, Jousilahti P, Salmoaa V, Korja M. Sex, Smoking, and Risk for Subarachnoid Hemorrhage. Stroke, 2016.