Psoriasis tends to worsen with weight gain. Flare-ups also can be triggered by certain common medications, like beta blockers used to control high blood pressure or heart rate, or lithium used to treat bipolar disorder. Other triggers include strep throat, injury to the skin, and respiratory infection. Once psoriasis has cleared up, it can stay away for months or even years, and then reappear. "You can minimize the risk for recurring flare-ups, but you cannot 100% avoid them, even if you do everything right," says Dr. Smith. Still, you should try to manage and avoid triggers, or at least keep them to a minimum. For instance, lose excess weight, and review your medications with your doctor to see if you should use an alternative or a different dose.