Apremilast, sold under the brand name Otezla, is an oral prescription medication used to treat moderate-to-severe plaque psoriasis and psoriatic arthritis. It works by blocking an enzyme called PDE-4, which helps reduce inflammation in the immune system. Apremilast may be a good option for people who want a pill instead of injections or biologic medications, especially when topical treatments alone are not enough. It does not usually require the same routine lab monitoring as methotrexate or some other systemic medications. Possible side effects include diarrhea, nausea, headache, upper respiratory symptoms, decreased appetite, weight loss, and mood changes or depression. Because stomach side effects can occur early, the dose is usually increased gradually when starting treatment.