Bimekizumab, sold under the brand name Bimzelx, is an injectable biologic medication used to treat moderate-to-severe plaque psoriasis in adults who may need systemic therapy or phototherapy. It works by blocking two inflammatory proteins, interleukin-17A and interleukin-17F, which are involved in the inflammation that drives psoriasis. Bimekizumab may be a good option for people with widespread, stubborn, or severe psoriasis that has not been controlled well enough with topical treatments or light therapy. It is given as a subcutaneous injection, usually with more frequent doses at the beginning and then maintenance dosing over time. Because it affects the immune system, clinicians usually screen for infections such as tuberculosis before starting treatment and monitor for side effects. Possible side effects include upper respiratory infections, oral thrush or other fungal infections, injection-site reactions, diarrhea, liver test abnormalities, and possible worsening of inflammatory bowel disease.