Topical Ketotifen 0.25% for Secondary Vestibulodynia

Inclusion Criteria: * Female participants ≥18 years of age * Able to provide signed and dated informed consent * Able to read, write, understand, and complete English-language study-related forms and communicate in English * Has a stable address and is available for the duration of the study * In good general health based on medical history * Willing to comply with all study procedures * Body mass index (BMI) between 18.5 kg/m² and 32.0 kg/m² (inclusive) * Meets ISSVD/ISSWSH/IPPS criteria for secondary provoked vestibulodynia, including: 6 continuous months of vulvar symptoms (insertional dyspareunia, pain with tampon insertion, or pain to touch); moderate to severe vestibular tenderness to light touch on physical exam * No evidence of vulvovaginal atrophy * If atrophy is present, must complete ≥12 weeks of topical hormone therapy and be re-screened to confirm resolution before enrollment * Negative vaginal culture for infection at randomization (participants with positive cultures at screening may be treated and retested) Exclusion Criteria: * Pregnancy or lactation * Unable to tolerate the smallest dilator during baseline dilator assessment * Active vaginal infection (Candida, BV, trichomonas, HSV) * May re-screen after treatment and documented cure * Active cutaneous disease of the vestibule * Current presentation of other painful vulvar conditions, including: Pudendal neuralgia Lichen sclerosus Lichen planus Plasma cell vulvitis Vulvar intraepithelial neoplasia Sjögren's disease Desquamative inflammatory vaginitis * Hypoestrogenic states (e.g., vulvar atrophy due to menopause or medications) * History of significant vestibular or vaginal surgery, including: Vestibulectomy Perineoplasty Bladder neck suspension Anterior/posterior colporrhaphy Pudendal nerve neurolysis Ablative or fractional laser procedures * Initiation or planned change in any of the following within 30 days before screening or during the study: Gabapentinoids Tricyclic antidepressants SSRIs or SNRIs Hormone replacement therapy Systemic or local muscle relaxants (benzodiazepines, baclofen, botulinum toxin, cyclobenzaprine, CBD suppositories) Pelvic floor physical therapy * Use of another investigational drug or intervention within the past 3 months * Positive vaginal culture during the study requiring two or more treatments (per protocol, second infection leads to termination) * Any condition or factor that, in the opinion of the investigator, would interfere with study participation or safety