If you smoke, quit. People with the habit are more likely to get psoriasis. Studies have shown that most people with pustular psoriasis who smoke were smokers before they got sick. The habit may trigger the disease in certain people. People who smoke at least a pack a day may have more severe psoriasis flare-ups, too. Treatments don't work as well on smokers, and smokers are less likely to have symptom-free periods between flare-ups.