If you're having trouble trying to quit smoking, there is a good reason. Studies have shown that smoking can be harder to quit than opiates, cocaine, or alcohol. But the effort is worth it. More than 480,000 deaths in the United States each year are caused by cigarette smoking. Smoking is this country's most preventable cause of death and disease.

While quitting tobacco use may require several attempts, success is possible, often with the help of nicotine-replacement therapies and counseling. Yale Medicine is a leader in tobacco dependence treatment and research, with research centers that investigate new therapies for smoking cessation, often through clinical trials.

Many smokers like to say they are not dependent on tobacco and can quit whenever they want. Don't be so sure. Here are some signs that you may be in deeper than you realize: 

• Difficulty cutting down or stopping tobacco use
• Continuing to smoke, despite smoking-related health symptoms 
• Giving up social or recreational activities in places where smoking is prohibited 
• Withdrawal symptoms if you stop temporarily, such as craving tobacco products, anxiety, restlessness, irritability, depressed mood, increased hunger, insomnia, concentration problems and bowel problems

In addition to being addictive, the chemicals found in tobacco products are extremely harmful. Cigarettes contain 600 ingredients which, when burned, produce 7,000 chemicals. At least 69 of these, such as ammonia, benzene, formaldehyde and lead, can cause cancer. The longer you smoke, the higher your risk of serious illnesses that include:

• Cancers such as lung, throat, stomach, liver and colorectal
• Stroke
• Respiratory disease
• Cardiac disease
• Cataracts and macular degeneration
• Damaged gums and teeth, sometimes including tooth loss
• Rheumatoid arthritis
• Peptic ulcers
• Type 2 diabetes
• In men: erectile dysfunction, reduced fertility and increased risk of birth defects in offspring
• In women: lower bone density, which can lead to hip and other fractures; altered menstrual cycle; transition to menopause, and pregnancy complications such as preterm births, low-weight babies and sudden infant death syndrome 

Chewing tobacco is associated with a higher incidence of mouth and throat cancers.

Yes. For instance, there is evidence that you may be more susceptible if you're a woman. According to Yale Medicine psychiatrist Ariadna Forray, MD, "women tend to use cigarettes to manage their anxiety, manage their stress level and manage their mood much more than men." Dr. Forray says women tend to react differently to treatment. "We know that women are less likely to respond to the nicotine patch or any other nicotine replacement therapies compared to men," she says. "We are still looking into why that is."

It also is well known that people who start smoking while they are still teenagers are more likely to be heavy smokers as adults. Researchers are still looking to confirm the reason why, but Dr. Forray says evidence points strongly toward the fact that young people's brains are still developing. "All the way through age 22, the brain is continuing to develop and changes continue to happen," says Dr. Forray, "so we know that exposure to smoking and other substances at any time during this period can alter susceptibility to substances."

Other factors that can make certain people more prone to tobacco addiction include genetics, mental health, drug abuse, and being around family and friends who use tobacco.

People seeking help for tobacco dependence should see their primary care physician, who will have valuable advice on treatment options.

The most successful path for treating tobacco dependence is often a combination of nicotine-replacement products such as "the patch," other federally approved medications such as varenicline (Chantix) and bupropion (Zyban), and counseling by a behavioral health professional.  

Dr. Forray says the combination approach might be especially good for women, who tend to respond less well than men to treatment with the patch alone (see "Are some people more likely to be hooked than others?" above). 

Along with the patch, which is most commonly used, nicotine-replacement products include gum, lozenges, inhalers, and nasal spray. They work by supplying a small amount of nicotine that satisfies a person’s nicotine craving while gradually helping to reduce the daily dose of nicotine. Nicotine replacement products are directly available from pharmacies.

When cognitive-behavioral therapy is used, it helps a person identify high-risk smoking situations, manage stress, and develop coping mechanisms. 

"Yale Medicine, through the Cancer Center, has a dedicated smoking cessation service, where people can receive any of these pharmacologic interventions or counseling or a combination of these in a personalized way," says Dr. Forray. "We have people who are trained in substance abuse treatment, and in particular they have training in smoking cessation."

Yale Medicine is also doing robust research. "The person leading the program does a lot of research on nicotine dependence and has a lot of expertise that can bring in the most innovative and evidence based treatments to our patients."

Yale Medicine research efforts, which often include free clinical trials that patients can join, include:

• The Yale Tobacco Treatment Clinic conducts clinical research into medications for smoking cessation.
• The Center for Nicotine and Tobacco Use Research Investigates treatments for smokers who cannot quit or have great trouble doing so, including women, people with mental health or medical problems, and heavy drinkers of alcohol -- groups that typically have difficulty with smoking cessation.
• Tobacco Research in Youth, a research team in Yale Medicine’s Department of Psychiatry, works to help young people quit smoking. Programs include participatory studies, surveys, and smoking prevention and cessation programs in 14 Connecticut high schools.
• The Yale Translational Center for Gender-Sensitive Treatment for Tobacco Dependence conducts basic and clinical research aimed at developing therapies for female smokers, who have lower smoking cessation rates and greater health risks than their male counterparts. Research shows that women are more likely to smoke to manage stress. The Translational Center is the world’s first to research medications that treat stress by affecting the noradrenergic system, which governs the neurotransmitter responsible for the “fight or flight” response, as a way to reduce smoking among women.
• The Yale Tobacco Center of Regulatory Science researches and advises the U.S. Food and Drug Administration (FDA) on how flavors and sweeteners in tobacco products affect their addictive properties, helping the FDA to develop science-based regulatory policies that will reduce addiction.