Is Smoking Bad After Surgery? What the Science Says

Smoking before or after surgery raises the risk of nearly every complication surgeons worry about, from wound infections and slow bone healing to breathing problems under anesthesia and blood clots. The evidence is not limited to a handful of studies; it stretches across virtually every surgical specialty and across decades of research. Complication rates for smokers consistently run higher than for nonsmokers, and the effects are not subtle. What makes the science especially interesting is how specific the damage is, how much timing matters, and how much of it can be reversed by quitting even just a few weeks before the operation.

How Smoking Disrupts Healing at a Basic Level

Two main culprits in cigarette smoke sabotage tissue repair. Nicotine is a powerful blood-vessel constrictor. It narrows the tiny vessels that supply skin, muscle, and bone, choking off the oxygen and nutrient flow a fresh wound needs to close. Carbon monoxide, the other key offender, latches onto hemoglobin with roughly 200 times the affinity of oxygen, crowding oxygen out of the bloodstream. Together, these effects create a double hit: the blood that does reach the wound carries less oxygen, and less blood reaches the wound in the first place.¹

This matters because tissue repair is an oxygen-hungry process. Immune cells need oxygen to fight bacteria at a surgical site. Collagen, the protein that knits a wound together, requires oxygen to form properly. When oxygen delivery is compromised, every stage of healing slows down, and the risk of infection rises.

Wound Infections and Wound Breakdown

Smokers are significantly more likely to develop surgical site infections. A large propensity-matched study found that smoking increased the odds of postoperative infection by about 30% and raised the odds of wound disruption, where the incision literally pulls apart, by roughly 65%.² Those numbers held even after researchers accounted for other variables like age and steroid use. In trauma patients specifically, the elevated infection risk persisted regardless of how severe the injuries were.³

Wound disruption is an underappreciated problem. When an incision reopens, recovery time can multiply. In some cases it requires a second surgery. For smokers facing major abdominal procedures, the combination of infection and breakdown can turn a straightforward recovery into a prolonged ordeal.

Lung Complications and Anesthesia Risk

Your lungs take a beating from smoking long before surgery, and anesthesia amplifies that vulnerability. In one study, current smokers had a roughly sixfold greater odds of developing a postoperative pulmonary complication compared with people who had never smoked. That risk remained nearly as high after adjusting for a long list of other factors including lung function, body weight, and pre-existing heart or lung disease.⁴ Pulmonary complications include pneumonia, collapsed lung segments, and the need for prolonged mechanical ventilation, all of which extend hospital stays and add serious risk.

Past smokers did better than current smokers in that same study, but their complication rate was still more than double that of never-smokers. The airway irritation, excess mucus, and reduced ciliary function that come with smoking do not fully reverse overnight.

More Pain and More Opioids

Smokers tend to experience more pain after surgery and require substantially more medication to manage it. A meta-analysis pooling data from multiple studies found that smokers required about a third more opioid medication than nonsmokers in the first 24 hours after an operation, and the gap persisted at 48 hours. Smokers also reported higher pain scores at the 24-hour mark.⁵

An observational study confirmed this pattern and added an important detail: the relationship is dose-dependent. The more cigarettes a person smoked per day, the more opioids they used both during and after surgery.⁶ Chronic nicotine exposure alters the brain’s pain-processing and reward pathways, which likely explains why smokers feel more pain and respond less readily to standard doses. At a time when clinicians are trying to minimize opioid prescriptions, smoking adds a frustrating wrinkle.

Bone Healing and Orthopedic Surgery

For anyone having fracture repair, spinal fusion, or joint surgery, smoking is one of the most potent risk factors for the bone not healing properly. A systematic review and meta-analysis covering more than 7,500 procedures found that smokers were about 2.2 times as likely to experience delayed union or nonunion, where the bone simply fails to knit together. Even when healing did occur, it took an average of nearly four extra weeks in smokers.⁷

A separate meta-analysis focused specifically on non-pathological fractures confirmed the pattern, finding that smokers had two and a half times the odds of nonunion compared with nonsmokers.⁸ Spinal fusion outcomes show a similar story. Smoking raises the risk of pseudoarthrosis (a false joint forming instead of a solid fusion) in both lumbar and cervical spine operations, along with infection and other perioperative problems.⁹

This is why some orthopedic and spine surgeons are among the most vocal about asking patients to quit. A spinal fusion that fails to fuse often means a second surgery, with all the cost, risk, and recovery time that entails.

Flap Surgery and Skin Grafts

Plastic and reconstructive surgeons have known for decades that smoking is devastating to flap surgery, where a section of tissue is moved from one part of the body to another and must establish its own blood supply. The vasoconstriction caused by nicotine can starve that tissue of blood, leading to partial or total flap loss. A study found that the rate of flap loss was almost five times higher in smokers than in nonsmokers.¹⁰ Hematomas and fat necrosis were also far more common.

This is why many plastic surgeons require patients to stop smoking for several weeks before and after procedures like breast reconstruction, facelifts, or abdominoplasty. The tissue simply cannot survive without adequate blood flow, and smoking directly undermines it.

Gut Surgery and Anastomotic Leaks

One of the most dangerous complications in bowel surgery is an anastomotic leak, where the surgical connection between two pieces of intestine fails, spilling contents into the abdomen. This can lead to life-threatening infection. In patients undergoing left colon resection, the leak rate for smokers was 17% compared with 5% for nonsmokers, giving smokers more than four times the odds of this complication.¹¹

Rectal cancer surgery shows the same vulnerability. Multivariate analysis identified current smoking as an independent risk factor for anastomotic leakage, with roughly three and a half times the odds of a leak compared with nonsmokers.¹² A study of rectal cancer patients also showed that the elevated risk persists for years after quitting: former smokers who had quit fewer than 10 years before surgery still had a significantly higher leak rate than lifelong nonsmokers.¹³ Only after a decade or more of abstinence did the leak risk drop to levels comparable with never-smokers.

Blood Clots and Cardiovascular Risk

Smoking makes blood more prone to clotting, which is the last thing you need during the enforced immobility after surgery. A large cohort study of women found that current smokers who underwent surgery had a significantly higher risk of venous thromboembolism (blood clots in the legs or lungs) in the 12 weeks after the operation compared with never-smokers.¹⁴ Smoking elevated clot risk both with and without surgery, but the two together created an especially hazardous window.

After cardiac procedures, the stakes are even higher. Patients who continued smoking following coronary artery bypass grafting or percutaneous coronary intervention had nearly twice the risk of heart attack, stroke, and death compared with those who quit.¹⁵

Longer Hospital Stays and Higher Readmission Rates

All of these complications translate directly into more time in the hospital and more trips back after discharge. Current smokers undergoing elective surgery had an average stay of 6.1 days compared with 4.7 days for nonsmokers. They also had about a 35% higher chance of being readmitted within 28 days, and the cost of those readmissions was significantly higher.¹⁶ Former smokers, interestingly, had readmission odds at least as high as current smokers, a finding that likely reflects the lasting lung and vascular damage from years of tobacco use.

When to Quit and Whether Late Quitting Helps

There is an old clinical myth that quitting smoking too close to surgery might actually make things worse, perhaps because the lungs temporarily produce more mucus during early cessation. A systematic review and meta-analysis addressed this directly and found no evidence that stopping smoking shortly before surgery worsens outcomes. The researchers concluded that patients should be advised to quit as early as possible, but that quitting at any point before surgery is better than not quitting at all.¹⁷

That said, more time smoke-free does mean greater benefit. A separate meta-analysis found that each week of cessation before surgery increased the protective effect by about 19%, and that programs with at least four weeks of cessation showed significantly better outcomes than shorter ones.¹⁸ Four to eight weeks is the sweet spot most guidelines aim for, though some specialty-specific risks, like the anastomotic leak data for rectal surgery, suggest that longer-term cessation matters for certain procedures.

What About Nicotine Replacement Therapy Around Surgery?

If quitting smoking is the goal, many patients reach for nicotine patches, gum, or lozenges. This raises a reasonable concern: if nicotine itself constricts blood vessels, does nicotine replacement therapy (NRT) carry the same surgical risks? The evidence is reassuring. A large propensity-matched analysis of smokers hospitalized for major surgery found no association between receiving NRT and complications, mortality, or readmission.¹⁹

A narrative review in a major medical journal reached a similar conclusion: while very high doses of nicotine in lab settings have reduced skin flap viability in animals, there is no evidence from human studies that NRT at standard doses increases healing-related or cardiovascular complications around surgery.²⁰ A systematic review in a surgical journal found that nicotine alone appears to have only a marginal effect on tissue oxygenation and healing, meaning the hundreds of other toxic chemicals in cigarette smoke account for the bulk of the surgical damage.²¹ The upshot is that policies prohibiting NRT in surgical patients deserve re-examination, because keeping patients on cigarettes is almost certainly worse than switching them to a patch.

Does Vaping Count?

Many patients assume that switching from cigarettes to e-cigarettes solves the problem. The research so far does not support that assumption. A systematic review of vaping and surgical wound healing concluded that e-cigarettes should be treated the same as tobacco cigarettes and stopped before surgery.²² E-cigarettes deliver nicotine inconsistently and in sometimes very high concentrations, and the vapor contains other compounds that depress immune function, impair wound healing, and may compromise bone repair.²³

The honest caveat is that the research on vaping and surgery is still thin compared with the mountain of data on combustible cigarettes. But the biological mechanisms overlap enough, and the early signals are concerning enough, that no surgical team is going to tell you vaping is fine around an operation.

Secondhand Smoke and Children Going into Surgery

Smoking does not only affect the person holding the cigarette. Children exposed to secondhand smoke at home face higher surgical risks, especially respiratory ones. A meta-analysis found that environmental tobacco smoke exposure more than doubled the risk of respiratory complications during and after anesthesia in children.²⁴ A separate study of children undergoing surgery found that 56% of those exposed to secondhand smoke experienced respiratory symptoms, compared with 31% of unexposed children.²⁵ If your child has surgery scheduled, quitting or at least keeping all smoke completely away from them in the weeks leading up to the procedure makes a measurable difference.

Surgery as a Chance to Quit for Good

One of the more hopeful findings in this research is that surgery appears to be a powerful motivational moment for permanent cessation. A study tracking over 5,000 smokers found that major surgery roughly doubled the likelihood of quitting, with about 8% of all quit events nationally being attributable to a surgical procedure.²⁶ People facing a tangible health threat with a clear link to smoking seem more open to change than at almost any other point in their lives.

Structured cessation programs launched around the time of surgery improve those odds further. In one trial, a program combining counseling and free NRT started about four weeks before surgery led to 36% of patients achieving complete abstinence through the perioperative period, compared with just 2% of controls. A year later, the intervention group was still more than twice as likely to be smoke-free.²⁷ Another trial found that patients randomized to a cessation intervention were roughly three times as likely to remain quit at one year compared with controls, and that lower baseline nicotine dependence was a strong predictor of success.²⁸

Even a minimal intervention makes a difference. A program designed to add little extra burden on physicians or nurses still resulted in roughly four times the cessation rate on the day of surgery and maintained significantly higher quit rates at 30 days.²⁹

Should Surgeons Require Quitting?

Given the overwhelming evidence, some surgical practices have considered making smoking cessation a prerequisite for elective procedures. This is ethically contentious. A survey of thoracic surgeons found them nearly evenly split on whether requiring patients to quit is ethical, and most (60%) did not actually impose such a requirement.³⁰ An empirical and philosophical study of both physicians and the general public concluded that the ethical case favors recommending cessation rather than requiring it, noting that mandating behavior changes can tip into paternalism.³¹

In practice, what most surgeons do is strongly recommend quitting, offer support through cessation programs and NRT, and occasionally postpone elective procedures when the complication risk is especially steep, as in spinal fusion or free-flap reconstruction. For urgent or emergency operations, the surgery obviously proceeds regardless of smoking status, and cessation efforts begin after the procedure.

Cannabis Smoke Before Anesthesia

Cannabis deserves a brief mention because patients often ask about it separately from tobacco. Smoked marijuana shares some of the same airway irritation and carbon monoxide exposure issues as tobacco, but it also introduces unique cardiovascular concerns under anesthesia. Research has found that marijuana users experienced a mean peak heart rate nearly 65% above their baseline during anesthesia, compared with about 39% in non-users, and the elevated heart rate took roughly twice as long to return to normal.³² For anyone with underlying heart disease, that kind of heart rate spike during surgery is a meaningful danger. If you use cannabis and have an operation coming up, your anesthesiologist needs to know.