Warts caused by the human papillomavirus (HPV) are one of the most common skin conditions among children. The prevalence of warts in school-aged children ranges from 10 to 20 percent. Warts are more common among immunocompromised patients [1, 2]. Some studies also show that the prevalence of viral warts in the pediatric population increases with age, peaking in adolescence. HPV is a DNA virus that replicates only in fully differentiated epithelial cells. More than 80 types of HPV have been identified. Types 27, 57, 2, and 1 are the most common types of HPV in skin warts in the general population. Warts usually affect patients of different age groups and various parts of the body, causing physical and psychological complications for patients (such as pain, discomfort, and embarrassment), which in turn lead to functional impairment. Warts often affect pressure points on the soles of the feet. Although most warts are asymptomatic, plantar warts are often associated with pain while walking, causing physical and psychological stress [3].

Various treatments such as keratolytic agents, cryotherapy, laser, antimitotic treatments, contact sensitizers, and intralesional injection of antigen have been used. There is no evidence that one treatment is superior to others, and in many cases, treatment of viral warts requires a combination of treatments. Treatment selection for patients should be based on variables such as wart size, number of lesions, anatomical location, patient preference, cost, convenience, side effects, and operator experience. It is important to emphasize that good communication between the patient, parents, and dermatologist is essential for successful treatment in children [2, 4].

Despite having various treatment approaches, treating plantar warts is challenging. No single treatment is effective in most patients, treatments are often painful, and they are associated with a high recurrence rate. Although nearly 75 percent of warts can resolve spontaneously within two years, patients often seek treatment for cosmetic reasons and pain. Many studies have examined the use of vitamin D compounds (calcipotriol) and 5-fluorouracil in wart patients separately or in combination with other drugs, but only one recent case report that tested the combination of these two showed very positive efficacy results [5, 6].

To date, no clinical trial has evaluated the combination of calcipotriol and 5-fluorouracil. Additionally, given that common current treatments such as cryotherapy are painful for children, achieving an effective, pain-free intervention is necessary. This study aims to evaluate the efficacy and side effects of the combination of 5-fluorouracil and calcipotriol in children (ages 4 to 18) with palmar and plantar warts in a randomized, double-blind, placebo-controlled clinical trial.

Inclusion Criteria: The inclusion criteria include the clinical or pathological diagnosis (only for suspicious lesions confirmed pathologically) of cutaneous warts on the palmoplantar area by a dermatologist. The patients' ages range from 4 to 18 years old, and the number of warts must be a maximum of 20.

Exclusion Criteria: The exclusion criteria include pregnancy and breastfeeding, warts on the face, inguinal, and genital areas, hypersensitivity to topical vitamin D derivatives or fluorouracil, extensive warts requiring other treatments, and receiving any treatment in the past two months. Patients with confirmed immunodeficiency will also be excluded from the study.