Smoking decreases blood oxygen and makes the heart and lungs work harder, leading to fatigue. Nicotine in tobacco can also cause an adrenaline rush, leaving someone feeling tired when it wears off.

Tobacco smoke contains more than 7,000 chemicals. According to the National Cancer Institute (NCI), smoking is the leading cause of early, preventable death in the United States.

Smoking narrows the blood vessels and reduces the supply of oxygen and nutrients to the organs and tissues. It can negatively affect energy levels, mood, skin, immunity, and other functions.

This article outlines why smoking reduces a person’s energy and its effects on other parts of the body.

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Tobacco contains nicotine, which is a mood-altering, addictive substance. When a person smokes, nicotine reaches their brain within seconds. This can make them feel energized due to stimulation of the adrenal glands, which release adrenaline.

The adrenaline rush triggers an increase in blood pressure, breathing rate, and heart rate. However, the effect wears off over time, leaving the person tired and craving another cigarette to reenergize them.

When a person smokes, they have more carbon monoxide and less oxygen in their bloodstream. They may also have narrower blood vessels, meaning the heart has to work harder to pump blood around the body. This extra energy required by the heart may reduce a person’s energy for other activities and make them tired.

Smoking harms just about every organ in the body. It causes a range of diseases and a general reduction in health. Cigarette smoking is responsible for almost 1 in 5 deaths in the U.S., which is more than 480,000 deaths annually.

The following sections outline the effects of smoking on the body.

Cardiovascular system

Smokers have a 2–4 times greater risk of developing coronary heart disease and stroke than nonsmokers.

Smoking harms the blood vessels, causing them to thicken and narrow and reducing the space for blood to flow. This means the heart needs to pump harder to deliver blood around the body, increasing blood pressure.

Smokers also have a higher risk of developing clots. When clots form in the blood vessels, they can restrict blood flow to areas such as the skin, legs, and brain, leading to a stroke.

Even people who smoke fewer than five cigarettes per day may show early signs of cardiovascular disease.

Respiratory system

Around 90% of lung cancer deaths and 80% of chronic obstructive pulmonary disease (COPD) deaths result from smoking.

Smoking harms the airways and alveoli — small air sacs in the lungs — making breathing difficult. If a person with asthma smokes, it can trigger an attack or make worsen the condition.

Learn about the difference between a smoker’s lungs and healthy lungs.

Skin, hair, and nails

Smoking can affect a person’s physical appearance. For instance, it contributes to premature wrinkling and skin aging. This may be because smoking causes the breakdown of collagen, which keeps the skin supple and elastic.

The physical act of drawing on a cigarette causes the mouth to pucker and the eyes to develop wrinkles known as “crow’s feet.” Cigarette smoke also causes the blood vessels to narrow, restricting the flow of nutrients and oxygen to the skin.

Additionally, people who smoke go gray and lose their hair faster. They can also develop discolored fingers and nails on their smoking hand.

Learn more about smoking’s effect on the skin here.

Mood and mental health

Some people continue to smoke because they feel that it relieves stress and tension. However, the opposite may be true. Smoking may actually increase tension and anxiety.

Smoking is addictive. If a person has not had a cigarette for a while, they may feel irritable and anxious. Nicotine in cigarette smoke activates reward pathways in the brain, temporarily reducing anxiety. Anxiety then increases when the nicotine rush subsides, and a person craves another cigarette, perpetuating the cycle of addiction.

There are high rates of smoking in people with depression and anxiety. Research from 2017 notes that it is unclear whether people with mental illness smoke to alleviate their symptoms or whether smoking contributes to their symptoms in the first place.

Immune system

People who smoke experience inflammation and decreased immune function. A compromised immune system can leave a person susceptible to health conditions ranging in severity from colds and flu to cancer.

The immune system may also become overactive. This could increase the severity of autoimmune conditions such as rheumatoid arthritis.

Health conditions

A 2018 study in Tobacco Induced Diseases found that people with multiple sclerosis (MS) who smoked had significantly higher levels of fatigue and depression than people with MS who did not smoke. They also had a lower health-related quality of life.

According to the study, the longer a person with MS had smoked, the worse their walking ability, depression, fatigue, and quality of life were. Quitting smoking may help improve these factors.

While many people associate smoking with lung cancer, it can cause cancer almost anywhere in the body.

Cancer or treatment for cancer can cause fatigue and affect people physically, emotionally, and psychologically.

Smoking can also have a range of negative effects on fertility in both males and females, including leading to:

After giving up smoking, a person will have more oxygen in the blood. Within 72 hours of stopping smoking, a person finds that breathing is easier and energy levels rise.

The Centers for Disease Control and Prevention (CDC) say that difficulty sleeping is a common problem among people who have recently quit smoking. Though this improves over time, a person may want to seek advice from a doctor if it is causing them serious problems. Feeling exhausted from giving up smoking can cause a person to fall back into the habit of smoking.

No matter how much a person smokes or for how long, giving up is one of the best things they can do to improve their health. Benefits of quitting include:

  • improving overall health and quality of life
  • reducing the risk of early death, adding up to 10 years to life expectancy
  • reducing the risk of a range of health problems
  • reducing the risk of cancer
  • improving outcomes if they already have coronary heart disease or COPD
  • improving health during pregnancy and fetal health

Learn more about what happens after quitting smoking here.

The best way to quit smoking may be different for everyone. However, every person aiming to quit will need to do the following:

  • change their behavior
  • learn to manage their nicotine withdrawal symptoms
  • find other ways to manage their stress and mood

Preparation is key to quitting successfully. Calling the CDC’s 800-QUIT-NOW quitline gives a person access to a coach who can help them make a plan to quit.

Nicotine replacement therapy may help some people quit. The CDC says people most commonly use nicotine patches alongside lozenges or gum.

Find 11 tips for giving up smoking here.

Smoking is the leading cause of preventable, early death in the U.S. It also causes a range of health issues affecting everything from the heart and lungs to energy levels and physical appearance.

Tiredness associated with smoking may be due to the effects of nicotine addiction, reduced oxygen in the bloodstream, or difficulty breathing.

A person can improve their energy levels and overall health by quitting smoking.