Harvard Health Letters

Even Light Smoking Carries Significant Risk

Even light smoking increases the risk of heart disease, lung cancer, cataract, and a host of other conditions.

If you think you're doing your heart and lungs a favor by smoking only "a little," think again. Light or intermittent smoking may be safer for you than heavy smoking, but can still cause plenty of harm.

Public health campaigns have reduced the number of American adults who smoke from 42 percent in 1965 to about 21 percent today. Along with that decline has come an increase in the number of light and now-and-then smokers. Experts long believed that smokers used light or intermittent smoking as a bridge to quitting. But it's becoming clear that more and more smokers continue this pattern indefinitely; almost one-quarter of all smokers today fall into these categories.

Light and intermittent smokers (sometimes called social smokers) often fly under the radar of doctors and others in a position to help them quit completely. When asked, "Are you a smoker?" or "Do you smoke?" they often answer, "No."

Nearly one-quarter of smokers have only a few cigarettes a day, or smoke only now and then.

Even light smoking increases the risk of heart disease, lung cancer, cataract, and a host of other conditions. Quitting completely is the best option for long-term health.


Dr. Rebecca Schane and her colleagues at the Center for Tobacco Control Research and Education at the University of California-San Francisco, reviewed nearly four dozen studies of light and intermittent smoking, along with data in the U.S. Surgeon General's report, "The Health Consequences of Smoking." They compiled this list of health hazards associated with light and intermittent smoking:

Heart disease due to high blood pressure and cholesterol-clogged arteries

Weakened aorta (an aortic aneurysm)

Premature death from cardiovascular disease

Lung, esophageal, stomach, and pancreatic cancer

Respiratory tract infections

Delayed conception in women and poorer sperm function in men

Slower recovery from torn cartilage and other injuries


Increased frailty in older men and women

Poorer health-related quality of life.

The risks ranged from a 50 percent increase for slower recovery from torn cartilage to a 500 percent increase for lung cancer in women. Light or intermittent smoking may also contribute to chronic obstructive pulmonary disease (chronic bronchitis or emphysema), stroke, peripheral artery disease, breast cancer, and other conditions, but there's not yet enough data to say for certain.

One aspect of light and intermittent smoking that puzzles experts is the role of nicotine dependence. Nicotine is the most addictive substance in cigarette smoke. The physical symptoms of nicotine withdrawal (which include drowsiness, irritability, difficulty concentrating, anxiety, and craving for tobacco) are what prompt smokers to reach for a cigarette again and again. Some light smokers feel the need to smoke every day. Others can go days or even weeks without smoking, but then experience a deep, sudden urge to do it.


Almost half of people who have only a few cigarettes a day, or who smoke only occasionally, don't consider themselves to be smokers, don't believe smoking poses much risk to their health, and feel they can quit any time. They're wrong on all counts.

Smoking one to four cigarettes a day, for example, increases the risk of heart disease almost as much as smoking a pack a day. Telling yourself, and your doctor, that you don't smoke doesn't negate these hazards, and it keeps you from getting help giving smoking completely.

When it comes to quitting, everyone is different. Some light and intermittent smokers have an easier time quitting than heavy smokers, while others find it just as difficult.

There are no formal guidelines to help light and intermittent smokers quit. Nicotine replacement may be appropriate for light, every-day smokers.

"I encourage my patients who are light or social smokers to keep nicotine gum handy for when they feel the urge to smoke," says Dr. Schane, a certified tobacco treatment specialist. Whether other quit-smoking medications, such as varenicline (Chantix) or bupropion (Zyban), are appropriate for very light or social smokers is an unanswered question.

Light smokers who believe their smoking isn't harmful to their own health may be moved to quit by messages that their smoke harms others. Passive smoking -- inhaling smoke from others' cigarettes, cigars, or pipes -- has a well-defined set of hazards that are similar to those from smoking.

While movies, ads and tobacco companies try to make smoking look cool, "it's time to stress the socially unacceptable aspects of smoking," says Dr. Schane. - Harvard Heart Letter


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Health - Even Light Smoking Carries Significant Risk