Quitting smoking generally improves the course of most autoimmune diseases, but the benefits arrive unevenly and some conditions temporarily get worse before they get better. A landmark 2024 study in Nature found that while smoking’s effects on the innate immune system fade relatively quickly after cessation, its impact on the adaptive immune system persists for years, locked in place by chemical changes to DNA. That split explains a lot about why someone who quits smoking might notice fast improvements in some health markers but find their autoimmune condition stubbornly slow to respond.
Your Immune System Does Not Simply Reset
The most important thing to understand about quitting smoking and autoimmune disease is that the immune system does not snap back to its pre-smoking state. Research published in Nature in 2024, drawing on a large French cohort, showed that smoking has two distinct immunological footprints. The effect on innate immune responses, your body’s first-line, general-purpose defense, fades once you stop smoking. But the effect on adaptive immunity, the more targeted system involving T cells and antibodies that goes haywire in autoimmune disease, persists long after the last cigarette. Past smokers in the study showed elevated levels of certain adaptive immune signals like IL-2 that were indistinguishable from current smokers and significantly different from people who had never smoked.1Nature. Smoking changes adaptive immunity with persistent effects
The mechanism behind this persistence involves epigenetic changes, essentially chemical tags on DNA that alter how genes are read without changing the genetic code itself. Smoking strips methyl groups off certain genes involved in immune signaling. After quitting, some of these sites slowly regain their methylation, but others remain altered for decades. One study tracking blood DNA methylation after cessation found that sites near immune-response genes like AHRR and F2RL3 begin reverting toward never-smoker levels relatively early, but the process is incomplete and variable.2PubMed Central. Longitudinal change in blood DNA epigenetic signature after smoking cessation Other research found that certain methylation sites remain altered even 35 years after quitting.3Nature Communications. Altered DNA methylation within DNMT3A, AHRR, LTA/TNF loci mediates the effect of smoking on inflammatory bowel disease The Nature study confirmed this pattern specifically for immune function: the longer someone had smoked, the more persistent the adaptive immune changes, while years since quitting correlated with gradual (but partial) methylation recovery.1Nature. Smoking changes adaptive immunity with persistent effects
Rheumatoid Arthritis Has the Most Data and the Most Surprises
Rheumatoid arthritis is the autoimmune condition most thoroughly studied in relation to smoking cessation, and the picture is more complicated than “quit and improve.” The long-term trends favor quitting. In a large study of over 3,300 RA patients, current smokers were significantly more likely to have moderate or high disease activity than former or never smokers. Former smokers also had substantially lower rates of cardiovascular events than those who kept smoking.4Rheumatology. Smoking cessation is associated with lower disease activity and predicts cardiovascular risk reduction in rheumatoid arthritis patients Pain scores tell a similar story: in one study, patients who quit saw their mean pain score drop from 37.5 to 3.0, compared with a more modest drop from 60 to 40 in those who continued. Disability scores and global health assessments also favored quitters.5PLOS ONE. A systematic review with meta-analysis of the effects of smoking cessation strategies in patients with rheumatoid arthritis
But the short-term picture can be discouraging. A 2025 randomized trial tested an intensive smoking cessation program in RA patients and found that at three months, participants who received the intervention had higher disease activity scores (averaging 3.2) than those in the control group (2.5). Treatment response rates were also lower in the intervention group initially. By twelve months, the differences between groups had evened out.6Rheumatology. Effect of an intensive smoking cessation intervention on smoking cessation and disease activity in patients with RA: a randomized controlled trial A Swedish study following early RA patients over eight years added another wrinkle: people who quit after diagnosis had worse clinical outcomes than those who had quit before diagnosis or who continued smoking. Heavy smokers who quit after enrollment were particularly likely to show no treatment response at two years.7PubMed Central. The Effect of Stopping Smoking on Disease Activity in Rheumatoid Arthritis (RA). Data from BARFOT, a Multicenter Study of Early RA
This does not mean quitting is the wrong call. The short-term flare likely reflects the immune system’s adjustment period, and there may be an element of confounding: patients who quit after diagnosis may have more severe disease to begin with, motivating the decision to change habits. The cardiovascular benefits alone make a strong case for cessation in RA, given that heart disease is a leading cause of death in people with the condition. But if you have RA and you quit smoking, a temporary uptick in symptoms is something to discuss with your rheumatologist rather than treat as a sign that quitting backfired.
Multiple Sclerosis Responds More Clearly
The evidence for quitting smoking in multiple sclerosis is more straightforwardly encouraging. A study published in JAMA Neurology compared MS patients who quit smoking with those who continued and found that quitters converted to the progressive phase of the disease at a median age of 56, while those who kept smoking converted at a median age of 48, a gap of about eight years.8JAMA Neurology. Effect of Smoking Cessation on Multiple Sclerosis Prognosis That is a meaningful delay in what is often the most disabling stage of MS.
Animal research helps explain why the non-nicotine components of cigarette smoke may be the main culprits. In a mouse model of MS, nicotine alone actually reduced disease severity, while a condensate containing the non-nicotine components of smoke worsened it. The two had opposite effects on the brain’s immune cells: nicotine appeared protective, while the tar and combustion byproducts drove inflammation and nerve damage.9PLOS ONE. The Experimental Autoimmune Encephalomyelitis Disease Course Is Modulated by Nicotine and Other Cigarette Smoke Components This distinction matters for people considering nicotine replacement therapy during cessation. Nicotine patches or gum remove the damaging smoke components while maintaining nicotine exposure, which in the context of MS may be a net positive during the transition period.
Ulcerative Colitis Is the Major Exception
Not every autoimmune condition improves when you quit. Ulcerative colitis is the best-known exception, and the relationship is genuinely paradoxical. Current smoking appears to protect against UC: smokers are less likely to develop it, and when they do, the disease tends to be milder. Quitting, by contrast, is associated with a higher risk of developing UC and with flares in people who already have it.10PubMed Central. Effect of smoking on inflammatory bowel disease: Is it disease or organ specific? Former smokers carry an elevated risk compared with both current smokers and people who never smoked. Nicotine has been explored as a treatment for UC in some cases, particularly in recent ex-smokers experiencing moderate but treatment-resistant flares, though its therapeutic role remains unclear.11PubMed Central. Ulcerative colitis in smokers, non-smokers and ex-smokers
Crohn’s disease, the other major inflammatory bowel disease, goes the opposite direction: smoking makes it worse, and quitting helps. The two diseases involve different parts of the gut and different immune pathways, which likely explains the divergence. If you have UC and are considering quitting, this is worth a serious conversation with your gastroenterologist. It does not mean you should keep smoking, since the cardiovascular and cancer risks of smoking far outweigh the UC-specific benefit, but your treatment plan may need adjustment around the time of cessation.
Lupus, Psoriasis, and Thyroid Eye Disease
For systemic lupus erythematosus, the evidence points toward quitting being helpful. A systematic review found that tobacco use was associated with increased lupus activity and the onset of skin damage.12Seminars in Arthritis and Rheumatism. Healthy lifestyle habits for patients with systemic lupus erythematosus: A systemic review Removing that trigger can reduce flares and improve how well lupus medications work, though the evidence base is thinner than it is for RA.
Psoriasis presents yet another mixed picture. Smoking clearly undermines treatment. A prospective study found that non-smokers were roughly 14 times more likely to achieve a meaningful reduction in psoriasis severity after eight weeks of treatment than current smokers. Former smokers did better than current smokers, roughly tripling their odds of treatment response, but still lagged behind people who never smoked.13Tobacco Induced Diseases. Tobacco smoking negatively influences the achievement of greater than three-quarters reduction in psoriasis area and severity index after eight weeks of treatment among patients with psoriasis However, a separate retrospective study concluded that smoking cessation alone does not appear to result in direct clinical improvement of psoriasis.14British Journal of Dermatology. Impact of smoking on response to systemic treatment in patients with psoriasis: a retrospective case–control study The takeaway seems to be that quitting makes your treatment work better rather than independently clearing up your skin.
Thyroid eye disease, a complication of autoimmune thyroid conditions like Graves’ disease, offers perhaps the most dramatic cessation benefit. A study tracking patients with thyroid eye disease found that those who quit smoking after counseling saw their severity scores improve by an average of about 4 points, while persistent smokers’ scores worsened by roughly 1.7 points.15PubMed Central. Mitigating the risks: addressing smoking cessation in thyroid eye disease Smoking is one of the strongest modifiable risk factors for this condition, and cessation is considered a core part of treatment.
Why Your Medications May Work Better After Quitting
One of the most practical reasons to quit smoking with an autoimmune disease is that your medications, particularly biologic therapies, are more likely to work. A prospective cohort study of patients starting biologics for chronic inflammatory diseases found that smokers had about half the odds of responding to treatment compared with non-smokers. The gap was sharpest in RA, where smokers had dramatically lower response rates.16PubMed. Effects of smoking on clinical treatment outcomes amongst patients with chronic inflammatory diseases initiating biologics Smoking interferes with how biologics are metabolized and may increase the formation of antibodies against these drugs, reducing their effectiveness. So quitting does not just address the underlying disease process; it removes a barrier to your existing treatment working properly.
This has practical implications for timing. If you are about to start a new biologic, quitting beforehand may give that drug its best chance. If you have been on a biologic and it seems to be losing effectiveness, smoking could be a contributing factor worth addressing before switching medications.
How Quickly Does Inflammation Come Down
C-reactive protein, a standard blood marker of inflammation, gives some sense of the timeline. A large prospective study found that CRP levels in former smokers decreased with increasing years since cessation, but the benefit was not detectable in the short term. It took more than eight years of abstinence before the reduction was statistically clear.17PubMed Central. Effect of Tobacco Smoking Cessation on C-Reactive Protein Levels in A Cohort of Low-Dose Computed Tomography Screening Participants A smaller pilot study of women going through a cessation program found that IL-6 and CRP both drifted downward during the program, but the changes did not reach statistical significance over that short period.18PubMed Central. A Pilot Study To Examine the Effects of Smoking Cessation on Serum Markers of Inflammation in Women at Risk for Cardiovascular Disease
This slow timeline matches what the epigenetic data tells us. If the DNA methylation changes underlying immune dysregulation take years to partially reverse, it makes sense that downstream markers like CRP would also be slow to normalize. The gap between quitting and measurable immune recovery is one of the least discussed but most important aspects of this topic. It means the benefits of cessation are partly invisible for years, which can make it hard to stay motivated if you are watching your lab work for proof that quitting helped.
E-Cigarettes and Alternative Nicotine Products
Switching from cigarettes to e-cigarettes is not the same as quitting, and the immune effects of this switch are poorly understood. Intriguing research has suggested that something about traditional cigarette smoke, possibly carbon monoxide or other combustion byproducts, may actually suppress the formation of antinuclear antibodies (ANA), which are markers of autoimmune activity. A study examining trends in ANA prevalence in the US population found that as cigarette smoking declined, ANA rates went up, and that e-cigarette users had higher ANA rates than traditional cigarette smokers.19Frontiers in Immunology. Decreased cigarette smoking may partially explain the increased prevalence of antinuclear antibodies in the United States
This does not mean cigarettes are “better” than e-cigarettes for autoimmune disease. ANA positivity alone does not equal autoimmune disease, and the overwhelming harms of combustible tobacco dwarf any hypothetical benefit from carbon monoxide exposure. But the finding underscores that nicotine delivery systems are not interchangeable when it comes to immune effects, and that the immunology of smoking involves far more than just nicotine. If you switch to vaping rather than quitting entirely, you are changing the chemical mixture your immune system sees, not simply getting a cleaner version of the same exposure.
Sex Differences in Immune Recovery
There is emerging evidence that the immune effects of smoking and the recovery from them differ between men and women. A population-based study examining cytokines and immunoglobulins found that IgM responses to smoking differed by sex.20PubMed Central. Immune Signatures of Smoking: Cytokine and Immunoglobulin Dysregulation and Partial Reversibility in a Population-Based Study Given that autoimmune diseases already affect women at much higher rates than men, sex-specific differences in how the immune system rebounds after cessation could have real clinical significance. This is still an underdeveloped area of research, but it may eventually help explain why some patients see faster immune recovery than others.
Secondhand Smoke and Autoimmune Risk in Children
The effects of smoking on autoimmune disease extend beyond the smoker. A study of pediatric multiple sclerosis found that children whose fathers were current smokers had roughly double the risk of developing MS. When both parents smoked, the risk was about twice that of children with non-smoking parents. Most strikingly, when both parents smoked in the three months before pregnancy, the risk jumped dramatically, though that estimate carried wide uncertainty due to small numbers.21Neurology and Therapy. Reducing Early-Life Smoke Exposure as a Preventive Strategy for Pediatric Multiple Sclerosis: Results from the PEDIGREE Study Smoking may also disrupt the microbiome in the lungs and gut, which can further influence the development of autoimmunity, making early-life avoidance of smoke exposure important as a preventive strategy.22JMA Journal. Cigarette Smoking: A Modifiable Environmental Factor in the Pathogenesis of Rheumatoid Arthritis
For parents with autoimmune conditions who worry about their children inheriting the same susceptibility, eliminating household smoke exposure is one of the few environmental interventions with supporting evidence. The benefits extend well before birth: the pediatric MS data suggest that even pre-conception smoking by either parent may matter, potentially through epigenetic effects on germ cells or through the chemical environment during the earliest stages of fetal development.