Smoking significantly increases the risk of developing psoriasis. Current smokers are roughly 63% more likely to develop the condition compared to people who have never smoked, based on a large meta-analysis pooling data across multiple studies. The relationship is dose-dependent: the more you smoke and the longer you smoke, the higher your risk and the more severe your symptoms tend to be.
How Much Smoking Raises Your Risk
A meta-analysis published in The Journal of International Medical Research calculated the odds for different smoking categories. Current smokers had a 63% higher risk of psoriasis than never-smokers. Former smokers still carried a 36% elevated risk. And when researchers grouped everyone who had ever smoked, the overall risk increase was 60%. These numbers tell a clear story: smoking doesn’t just trigger flares in people who already have psoriasis. It raises the likelihood of developing the disease in the first place.
The relationship follows a dose-response pattern. A study in JAMA Dermatology found that people who smoked more than a pack a day (over 20 cigarettes) had twice the risk of severe psoriasis compared to those who smoked 10 or fewer cigarettes daily. Over a lifetime, accumulating the equivalent of 20 cigarettes a day for 30 years was associated with a 30% increased risk of more severe disease. In short, heavier and longer smoking correlates with worse outcomes.
How Smoking Triggers Psoriasis at a Cellular Level
Psoriasis is driven by an overactive immune system that attacks healthy skin cells, causing them to reproduce too quickly and pile up into thick, inflamed patches. Smoking feeds directly into this process through several pathways.
Tobacco smoke generates oxidative stress, flooding the body with unstable molecules called free radicals. These free radicals interfere with key signaling pathways that regulate inflammation and skin cell growth. At the same time, nicotine ramps up the production of inflammatory signaling molecules, including some of the most important drivers of psoriasis: tumor necrosis factor (TNF), interleukin-12, and interleukin-2. These are the same molecules that biologic medications for psoriasis are designed to block. Lab studies on human skin cells have confirmed that cigarette smoke extract directly increases TNF production by activating a specific protein that turns on inflammatory genes.
Essentially, smoking pours fuel on the exact immune pathways that cause psoriasis to develop and worsen.
Genetics Can Multiply the Risk
Some people carry a gene variant called HLA-Cw6, one of the strongest known genetic risk factors for psoriasis. A hospital-based study in China found that carrying this gene alone increased psoriasis risk nearly tenfold. But when researchers looked at smokers who also carried HLA-Cw6, the risk jumped to about 11 times that of non-smokers without the gene. Adding stressful life events on top of the genetic variant pushed the risk to roughly 20-fold.
This means smoking doesn’t act in isolation. If you have a family history of psoriasis (which often signals the presence of high-risk gene variants), smoking may be an especially dangerous trigger. The combination of genetic susceptibility and tobacco exposure creates a compounding effect far greater than either factor alone.
Palmoplantar Pustulosis and Smoking
One specific subtype of psoriasis has an unusually strong link to smoking: palmoplantar pustulosis, which causes painful, pus-filled blisters on the palms and soles. A multicentre case-control study comparing 216 patients with this condition to 626 controls found a considerably higher prevalence of smoking among the pustulosis group. This was one of the earliest indications that smoking may directly alter inflammatory responses in the skin, and the connection has been confirmed repeatedly since.
Secondhand Smoke Affects Children Too
The risk isn’t limited to people who smoke themselves. A case-control study on childhood psoriasis found that children exposed to secondhand smoke at home had more than double the risk of developing the disease (a 123% increase), even after researchers accounted for family history of psoriasis and obesity. Interestingly, exposure to tobacco during pregnancy alone did not show a statistically significant link. It was the ongoing environmental exposure after birth that mattered most. This makes household smoking an important and preventable risk factor for psoriasis in children.
Does Smoking Affect Treatment?
If you already have psoriasis and smoke, you might wonder whether smoking will make your treatment less effective. The evidence here is somewhat reassuring. A study of psoriasis patients on biologic therapies (the injectable medications used for moderate to severe cases) found that smokers and non-smokers had nearly identical response rates. About 50% of patients in both groups achieved complete skin clearance after one year, and the average improvement in disease severity scores was virtually the same. A separate retrospective study of 350 patients in Italy reached the same conclusion for several different biologic medications.
That said, these findings don’t mean smoking is harmless for people with psoriasis. Smoking still worsens disease severity overall and increases the burden of cardiovascular disease, which is already elevated in people with psoriasis.
What Happens When You Quit
Quitting smoking lowers your risk, though it doesn’t erase it entirely. The meta-analysis data shows former smokers carry a 36% elevated risk of psoriasis compared to never-smokers, while current smokers sit at 63%. That gap represents a meaningful reduction, suggesting that some of the inflammatory damage from smoking is reversible over time, but that years of tobacco exposure leave a lasting imprint on immune function.
For people who already have psoriasis, quitting removes an ongoing source of oxidative stress and inflammatory signaling that directly fuels the disease. While no study has established a precise timeline for skin improvement after quitting, reducing the inflammatory load on your immune system works in the same direction as every psoriasis treatment available.