Health Topic

Smoking

There's no way around it. Smoking is bad for your health. Learn the effects of smoking (how smoking harms nearly every organ) and how to quit.

Reviewed Reviewed by a registered pharmacistGeneral information

Also called: Cigar smoking · Cigarette smoking · Pipe smoking · Tobacco smoking

Important: This page is general information, not medical advice. It does not recommend or prescribe any treatment. Always consult your doctor or pharmacist before starting, stopping or changing any medicine.

About Smoking

There's no way around it; smoking is bad for your health. It harms nearly every organ of the body, even some that you would not expect. Cigarette smoking causes many cancers and other health problems. It is also the cause of nearly one in five deaths in the United States.

Some of the many health problems that smoking can cause include:

  • Cancers. Smoking is the most common cause of lung and oral cancers. But it can also cause cancer in many other parts of your body, such as in your larynx (voice box), esophagus, throat, bladder, kidney, liver, stomach, pancreas, colon and rectum, and cervix. It can also cause acute myeloid leukemia (AML).
  • Lung diseases. Smoking is the most common cause of COPD. It can also worsen asthma and raise your risk of pneumonia.
  • Cardiovascular diseases. Smoking can damage your blood vessels and make them thicken and grow narrower. This makes your heart beat faster and raises your blood pressure. Smoking also increases your risk of blood clots and stroke.
  • Vision problems. Smoking can raise your risk of cataracts and cause macular degeneration (AMD).

You have a greater chance of certain pregnancy problems if you smoke while pregnant. Your baby is also at higher risk of dying of sudden infant death syndrome (SIDS).

Smoking also causes addiction to nicotine, a stimulant drug that is in tobacco. Nicotine addiction makes it much harder for people to quit smoking.

Your smoke is also bad for other people. If they breathe in your secondhand smoke, they can get many of the same problems as smokers do. These problems can include heart disease and lung cancer. Children exposed to secondhand smoke have a higher risk of ear infections, colds, pneumonia, bronchitis, and more severe asthma. If you breathe secondhand smoke while pregnant, you're more likely to have preterm labor and a baby with low birth weight.

Besides cigarettes, there are several other forms of tobacco. Some people smoke tobacco in cigars and water pipes (hookahs). These forms of tobacco also contain harmful chemicals and nicotine. Some cigars contain as much tobacco as an entire pack of cigarettes.

E-cigarettes often look like cigarettes, but they work differently. They are battery-operated smoking devices. Using an e-cigarette is called vaping. Researchers still have a lot to learn about the health effects of using e-cigarettes. We do know that they contain nicotine, which is highly addictive and a health danger to you and your fetus if you are pregnant, children, and teens. And e-cigarettes also expose non-smokers to secondhand aerosols (rather than secondhand smoke), which contain harmful chemicals.

Smokeless tobacco, such as chewing tobacco and snuff, is also bad for your health. Smokeless tobacco can cause certain cancers, including oral cancer. It also increases your risk of getting heart disease, gum disease, and oral lesions.

Remember, there is no safe level of tobacco use. Smoking even just one cigarette per day over a lifetime can cause smoking-related cancers and premature death. Quitting smoking can reduce your risk of health problems and add years to your life. The earlier you quit, the greater the benefit. Some immediate benefits of quitting include:

  • Lower heart rate and blood pressure
  • Less carbon monoxide in the blood (carbon monoxide reduces the blood's ability to carry oxygen)
  • Better circulation
  • Less coughing and wheezing

Quitting smoking can be challenging, but it is so important for your health. Contact your health care provider if you need help quitting.

It sits within Substance Use and Disorders and Lungs and Breathing.

The lead U.S. institute for this subject is the National Institute on Drug Abuse.

When to speak to someone. Reading about a topic cannot tell you whether it applies to you. Speak to a doctor or pharmacist if symptoms are severe, sudden, getting worse, or simply not going away — and seek emergency care immediately for chest pain, breathing difficulty, sudden weakness or confusion, or a serious allergic reaction.

Research on Smoking

3,837 studies areregistered for this condition on ClinicalTrials.gov, the U.S. National Library of Medicine's public registry. A selection is below — the links go straight to the registry entry, not to a summary of ours.

What a registered study does and does not mean. Registration means a study exists and has been declared publicly. It says nothing about whether the treatment being tested works, is safe, or is available to you. Many studies find no benefit — that is what research is for. Never seek out an experimental treatment on the strength of a registry entry alone.

Research currently under way

Research already completed

Study data from ClinicalTrials.gov, a service of the U.S. National Library of Medicine. Retrieved 2026-07-30. Registry entries are supplied by study sponsors and investigators; ClinicalTrials.gov does not verify their scientific validity. PocketsInfo is not affiliated with, and not endorsed by, the NLM or the NIH.

Where to read more

Rather than paraphrase, we point you to the primary sources. Every link below is to a government health agency, a national institute or a recognised medical body — grouped by what you are trying to find out.

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Related Issues

Statistics and Research

Clinical Trials

Medical subject headings

Clinicians and researchers index this subject under Cigarette Smoking, Pipe Smoking, Tobacco Smoking, Water Pipe Smoking, Cigar Smoking. These are the terms to use when searching medical literature.

This page is built from the MedlinePlus health topic record for Smoking, a service of the U.S. National Library of Medicine (NLM), National Institutes of Health. Information is from MedlinePlus.gov. PocketsInfo is not affiliated with, and is not endorsed by, the NLM or the NIH. Retrieved 30 July 2026.