When you quit smoking, this is how your body changes

So you've decided to quit smoking, once and for all? Congratulations! You've just taken an important first step toward improving your health. According to the Centers for Disease Control and Prevention (CDC), 13.7 percent of American adults (34.2 million people) smoke cigarettes. An estimated 16 million of such ones live with a smoking-related condition such as heart disease or emphysema.

Smoking has been shown to directly cause or increase your risk for many diseases, including cancer, heart disease, stroke, diabetes, emphysema, chronic bronchitis, tuberculosis, eye issues, and immune problems. It's also the leading cause of preventable disease and death in the United States, causing one in five deaths. Even just being around cigarette smoke is dangerous; the CDC reported that 41,000 nonsmoking adults die each year from secondhand smoke.

Nevertheless, quitting isn't easy. Although roughly two-thirds of smokers have a desire to quit, only a little more than half of smokers actually attempt to quit in any given year. Of those, 7.5 percent will successfully quit each year. That doesn't mean you should give up, though. Your chances of success increase with every attempt you make. And once the smoke clears (literally), you'll find that your body has changed a lot since quitting.

Your lungs will heal when you quit smoking

Many smokers worry that they've done irreparable damage to their lungs after years of smoking. The good news is that your lungs have an amazing capacity to heal themselves once cigarette smoking ceases. 

Oncologist Tirrell Tremayne Johnson explained in an article for Orlando Health how the lungs respond once you stop smoking: "Smoking ... inflames the lining of the airways, but when you quit, you no longer inhale all the toxic substances that irritate the airways, which allows them to begin healing." And the changes begin right away. Within 20 minutes to three days, airways relax and open up, while the cilia (the hair-like structures that line your airways) become active and remove irritants out of the lungs.

Between one and nine months after quitting, the cilia regrow and function normally. Coughing and shortness of breath also decreases during this time. By just two months, your lung function will have increased by 30 percent. After 10 years, an ex-smoker is 50 percent less likely than a current smoker to get lung cancer and has the same risk as a nonsmoker of dying from the disease. Johnson cautioned, however, that some lung damage may be permanent. Emphysema, for instance, can alter the structure of your airways and reduce lung function forever.

Quitting smoking will lower your blood pressure

According to the Centers for Disease Control and Prevention, approximately 45 percent of Americans have high blood pressure, defined as a systolic pressure (when the heart contracts) of 130 mmHg or higher or a diastolic pressure (when the heart is relaxed between beats) of 80 mmHg or higher. Having high blood pressure greatly increases your risk for both heart disease and stroke.

While many smokers feel like smoking calms them down, nicotine actually raises blood pressure, according to American Family PhysicianNicotine stimulates the body's central nervous system and prompts it to release epinephrine. This hormone is part of the "fight or flight" response and produces a number of effects in the body, including an increase in blood pressure and heart rate.

Luckily, blood pressure begins to return to normal only 20 minutes after your last cigarette. In a study published in Hypertension, researchers found that after a week of not smoking, the levels of epinephrine and norepinephrine (a similar hormone) in smokers' blood was significantly lower. This led to a decrease in daytime blood pressure of about 3.5 mmHg systolic pressure and 1.9 mmHg diastolic pressure.

Your heart health will improve when you quit smoking

Heart disease claims the lives of more than 800,000 Americans annually and is the leading cause of death in the country, according to the Centers for Disease Control and Prevention. Smoking causes approximately a quarter of heart disease deaths.

The toxic chemicals in cigarettes cause blood vessels to become swollen and inflamed, constricting blood flow. This can lead to atherosclerosis, a condition in which arteries narrow and harden as plaques build up along the vessels' walls. Eventually this buildup can cause a blockage, leading to a heart attack or stroke. It can also weaken arteries to the point that they rupture, causing an aneurysm in the aorta (the main artery leaving the heart) or in the brain.

Once you quit smoking, the inflammation in your arteries begins to decrease. Within just one day, your risk for heart attack lowers, and at the end of one year your risk for heart disease is half that of someone who still smokes. In three to five years, your risk of dying from a heart attack is the same as a nonsmoker, and at the 15-year mark, your risk of getting heart disease is the same as a nonsmoker's.

When you quit smoking, your blood oxygen level will increase

Every cell in your body needs oxygen to function, so having enough oxygen circulating in your blood is critical for good health. When you smoke, the carbon monoxide in cigarettes "crowds out oxygen in your blood," WebMD explained. Carbon monoxide levels in nonsmokers range between 0 and 8 parts per million (ppm), but pack-a-day smokers have values around 20 ppm. Carbon dioxide is deadly in high concentrations, but chronic exposure also carries risks, like heart disease.

Blood oxygen level is most often measured with a pulse oximeter, a little device that clips on to the end of your finger. According to Healthline, normal oxygen levels range between 95 and 100 percent. Smokers, however, may get artificially high readings because the pulse oximeter can't tell the difference between oxygen and carbon monoxide in the blood.

Once you stop smoking, your carbon monoxide levels drop quickly and your blood oxygen level improves. Within about eight hours, your carbon monoxide and oxygen levels return to normal.

Your cholesterol will improve when you quit smoking

If your doctor has told you that you have high cholesterol, quitting smoking is a lifestyle change you can make to improve your numbers. According to a 2013 paper published in the Journal of Cellular Biochemistry, cigarette smoking "appears to disrupt lipid and lipoprotein metabolism; smokers have elevated plasma cholesterol, triglycerides and LDL-c, [bad cholesterol] and lower HDL-c [good cholesterol] levels as compared to non-smokers."

The authors noted that smoking's effects on HDL were particularly dangerous. Not only does smoking reduce the amount of HDL in the blood, it also appears to change this "good" cholesterol into a substance that may actually harm artery walls rather than protect them.

Once you quit smoking, it will take some time for your numbers to improve. There are also many other factors (such as diet and exercise) that can either help or hinder your progress. HDL can increase in about six weeks, while it may take a few months for triglyceride levels to drop.

Your circulation will improve when you quit smoking

If your hands and feet are always cold, your nicotine habit may be to blame. As a 2016 study published in the journal Trends in Cardiovascular Medicine explained, "Nicotine constricts blood vessels, including those in the skin and coronary blood vessels [the vessels providing oxygen to the heart], but dilates blood vessels in skeletal muscle." Reduced blood flow to the skin can cause fingers and toes to feel cold.

The circulation issues associated with nicotine can lead to a number of other, more serious problems. According to nurse practitioners Catherine Cristofalo and Amy Ward, these include "heart attack, stroke, aneurysm, peripheral arterial disease (PAD), limb loss, and erectile dysfunction." Even young smokers aren't immune to these complications. Buerger's disease, for instance, can affect smokers in their 20s and can result in limb amputation because of poor blood circulation.

Thankfully, circulation begins to improve almost immediately once you stop smoking. Within 20 minutes of your last cigarette, blood flow to hands and feet increases. You can expect to see additional improvements in circulation sometime between two weeks and two months after quitting.

When you quit smoking, your senses will become sharper

You may not realize it, but smoking has probably dulled your senses of smell and taste. According to Raleigh Capitol Ear, Nose and Throat, "smokers are six times more likely to have poor smell than non-smokers." The chemicals in cigarettes damage the nerves that convey information from the nose to the brain. And, like most of smoking's negative effects, the more cigarettes you smoke each day, the more your sense of smell will be affected.

Your senses of smell and taste are closely interconnected so it's no surprise that smoking can also dull the taste of food. In fact, in an interview with WebMD, researcher Pavlidis Pavlos noted that smoking can change both the shape of your taste buds and how they function. Smokers' taste buds tend to be flatter and have poorer vascularization (blood flow) than nonsmokers' taste buds.

Nerve endings begin to regenerate within about 48 hours of your last cigarette, so improvements to smell and taste will happen fairly quickly. Once you've been nicotine-free for a while, you may even notice improvements in your hearing and vision.

Your skin will improve when you quit smoking

The toxic chemicals in cigarettes damage collagen and elastin, the proteins that give skin its structure and suppleness, according to Verywell Mind. This can lead to signs of premature aging — including wrinkles and sagging — especially in places where the skin is thin, like the face, neck, and hands. Nicotine also causes poor circulation, which in turn leads to impaired wound healing, leaving you with lingering scabs and scars. It can also cause spider veins and vasculitis and aggravate psoriasis. Additionally, smoking gives the skin an uneven tone due to poor oxygenation and increases your risk for a type of skin cancer called squamous cell carcinoma (SCC) by as much as 52 percent.

Once you quit smoking, your skin begins to heal. Increased blood flow brings vital nutrients to the skin, and elastin and collagen regenerate. Even after just a few days cigarette-free, your complexion will look brighter and pinker, and your skin may be less saggy. You won't be able to completely erase the damage smoking has done to your skin, but you'll likely see significant improvements.

Your body will be able to tolerate more exercise when you quit smoking

All the cardiovascular and respiratory improvements that come with quitting cigarettes mean that your body will be better equipped for exercise. Not only will you be more able to do the physical activities you love, like hiking, biking, or playing a sport, but being able to exercise more also means you're further lowering your risk for chronic conditions like heart disease.

In a 2013 study published in the American Heart Journal, researchers used a treadmill stress test to monitor smokers' cardiovascular response to exercise. They found that smokers have lower exercise capacity, lower heart rate reserve, and it takes longer for their heart rate to return to normal after they stop exercising. When they retested participants three years later, those who'd quit smoking showed improvements in all of these areas.

Similarly, a study published in the American Journal of Cardiology found that women who quit smoking saw improvements in both how long they were able to exercise and their peak oxygen consumption (a measure of exercise endurance). Two weeks to two months after quitting, you'll find that walking has become easier. By the nine-month mark, you'll feel much more energetic.

Your sex life will improve when you quit smoking

Despite what cigarette ads of the past claimed, there's nothing sexy about smoking. "Smoking can cause erectile dysfunction in men as young as 20," TheTruth.com revealed. That's because the chemicals in cigarettes cause buildup of plaques on artery walls, including the arteries that supply blood to the penis. As the plaques accumulate, blood flow is restricted and it becomes much more difficult to achieve and maintain an erection. A study cited by WebMD further revealed that nonsmoking men engaged in sex about twice as frequently as men who smoke.

Additionally, nicotine reduces "physiological sexual arousal" and "genital responses" in women by 30 percent, according to a study published in the Journal of Sexual Medicine. The U.K.'s National Health Service (NHS) reported that once you stop smoking, improvements in blood flow will lead to better erections and women can look forward to an easier time becoming aroused and better orgasms. The NHS also pointed out that "non-smokers are 3 times more appealing to prospective partners than smokers."

When you quit smoking, you'll have an easier time getting pregnant

It's now common knowledge that smoking during pregnancy can harm a developing fetus, but experts now agree that smoking may also make it harder to get pregnant in the first place.

According to the American Society for Reproductive Medicine, infertility rates among smokers are twice those of nonsmokers. IVF treatments are also about 30 percent less effective for smokers compared to nonsmokers. Nicotine, cyanide, carbon monoxide, and other chemicals in cigarettes speed up the natural rate at which a woman loses viable eggs. This means that women who smoke hit menopause one to four years earlier than nonsmokers. In men, smoking can cause lowered sperm counts, poor sperm motility, and abnormally shaped sperm. Sperm may also be less able to fertilize eggs.

Although the loss of viable eggs can't be reversed, the Cleveland Clinic reported that once women stop smoking their chances of getting pregnant double each month. It takes about 90 days for both sperm and an egg to mature, so you can expect to begin to see improvements in fertility about three months after you quit. Doctors recommend quitting at least a few months before you plan to start trying for a baby.

Your immune system will become stronger when you quit smoking

Considering the many toxic chemicals found in cigarettes, it's no surprise that smoking can put a huge stress on the immune system. An immune system weakened by smoking is less efficient and less able to protect the body from bacterial and viral infections, free radical damage to cells, and cancer. Smoking also contributes to and worsens autoimmune conditions, like rheumatoid arthritis.

A study published in the Journal of Allergy and Clinical Immunology found that just one month after quitting, ex-smokers' natural killer cells were more active. Natural killer (NK) cells are a part of the immune system designed to respond quickly to a large number of threats. They are especially good at destroying cells infected by viruses and detecting and destroying early signs of cancer. The increased NK cell activity was observed in former light-to-moderate smokers as well as those who were once heavy smokers. You can expect additional improvements in your immune system about eight weeks after you quit.

When you quit smoking, you may gain weight

Quitting cigarettes is one of the healthiest decisions you can make, but it isn't easy. There may also be some side effects to contend with. One of those is weight gain. Medline Plus noted that people gain an average of 5–10 pounds in the months after they quit smoking.

Britain's National Health Service (NHS) identified several reasons why quitting smoking can cause a person to pack on the pounds. For one, nicotine speeds up your metabolism and suppresses your appetite. Because quitting can improve your senses of smell and taste, food is also likely to be more enjoyable than it used to be and you may find yourself overindulging on tasty treats. It's also possible to mistake nicotine cravings for hunger, and many people use food as a way to distract themselves during nicotine withdrawal.

Finally, you may find yourself subconsciously replacing the hand-to-mouth motion of smoking with the hand-to-mouth motion of eating. But don't despair! The NHS noted that by exercising, choosing healthy foods, and using medication to suppress nicotine cravings, you can minimize weight gain.

Your mental health will get a boost when you quit smoking

Most smokers say that they feel calmer when they light up, but cigarettes actually cause the stress and anxiety they seem to relieve. According to Britain's National Health Service, nicotine cravings cause feelings of tension and irritability that are temporarily appeased with a cigarette, but it's the habit of smoking that created these feelings in the first place.

Smokers are more likely than nonsmokers to be diagnosed with depression, and smokers with mental health disorders tend to smoke more and need higher doses of antidepressants, antipsychotics, and other medications. Quitting reduces feelings of depression, stress, and anxiety. It also improves mood and may allow some individuals to reduce their medication levels. A 2011 study published in Nicotine & Tobacco Research, for instance, concluded, "During the first 6 months following a planned quit attempt, being abstinent in a particular week appears to be associated with lower levels of concurrent depressive symptoms."

However, nicotine withdrawal is no joke. Once you've decided to quit, be prepared for some difficult — but temporary — psychological symptoms, including anxiety, depression, irritability, and brain fog. These problems will resolve as your body readjusts to life without nicotine.