Mumps antigen injections are a form of intralesional immunotherapy used to treat stubborn or multiple warts. A small amount of mumps antigen is injected directly into the wart to activate a targeted immune response against HPV-infected skin cells. Similar to Candida antigen therapy, this approach may also help clear untreated warts elsewhere on the body by boosting systemic immunity. Treatments are typically repeated every 3–4 weeks until improvement is seen. It is generally well tolerated, though temporary swelling or soreness at the injection site can occur, and it is most effective in patients who already have immune memory to mumps (e.g., prior vaccination or infection).