The goals of pharmacotherapy are to reduce morbidity and prevent complications. In addition to the medications listed below, propolis is a brownish resinous waxy material collected by honeybees from the buds of trees and used as a cement and used at 500 mg/day until warts resolve or until 3 mo, whichever occurs first.
Dibutyl squaric acid/diphencyclopropenone has also been used. Contact sensitizers induce allergic contact dermatitis, causing a localized inflammation and immune response. Apply solution in light-shielded accessible location (eg, arm) to achieve initial sensitization; repeat until reaction occurs; apply to warts q1-2weeks.
Immunomodulators have been used 
The British Association of Dermatologists has treatment guidelines for cutaneous warts. See British Association of Dermatologists' Guidelines for the Management of Cutaneous Warts 2014 for more information. 
Keratolytic agents cause cornified epithelium to swell, soften, macerate, and then desquamate.
Salicylic acid topical (Compound W, Compound W for Kids, Dr. Scholl's Advanced Pain Relief Corn Removers)
Salicylic acid is available over the counter in 5-40% concentration and in a variety of vehicles, including creams, paints, gels, karaya gum, impregnated plasters, collodion, or sodium carboxycellulose tape. Lactic acid may be a second ingredient in some wart varnishes. By dissolving the intercellular cement substance, salicylic acid desquamates the horny layer of skin. Therapeutic effect may be enhanced by removal of surface keratin prior to application. Apply topically once or twice daily for several weeks.
Podofilox is a purified ingredient of podophyllin and, therefore, is less irritating. It is available by prescription and can be applied by the patient at home. A 0.5% purified solution may be applied topically twice daily for 3 consecutive days, repeated weekly, not exceed 4 weeks.
Podophyllum resin is an extract derived from the May Apple plant that contains several cytotoxic compounds. It has a powerful irritant effect and must be used with caution. It works better on mucosal surfaces than keratinized surfaces and is therefore more commonly used for genital warts. Trained personnel must apply it topically because of adverse effects; it may be left on the skin for 1-6 hours before washing.
Cantharidin is the dried extract of the blister beetle (also termed Spanish fly). It causes epidermal necrosis and blistering. Apply the 0.7% solution sparingly with the wooden end of cotton-tipped applicator in the physician's office, and allow it to completely dry; do not cover the area with a bandage after application; repeat the application at 3- to 4-week intervals may be required.
Trichloroacetic acid is a caustic compound that causes immediate superficial tissue necrosis. It is available as 80% solution that is painted onto lesions in the physician's office; apply after excess keratotic debris is pared; repeat therapy weekly as necessary until the wart is cured.
Immunomodulators stimulate the release of key factors that regulate the immune system.
Imiquimod induces secretion of interferon alpha and other cytokines; it is FDA approved for the treatment of genital warts in adults; reports indicate success in the treatment of common warts in children. It is a 5% gel that is applied daily for 3 d/wk; it may be applied before bedtime and washed off after 6-10 hours; twice-daily administration for nongenital warts has been reported, but irritation may be increased.
Interferon alfa 2b is a naturally occurring cytokine with antiviral, antitumor, and immunomodulatory actions; intralesional administration is more effective than systemic administration and is associated only with mild flulike symptoms. Treatments may be required for several weeks to months before beneficial results are seen. Consider this treatment as third line, and reserve it for warts resistant to standard treatments.
PEG-IFN alfa-2a consists of IFN alfa-2a attached to a 40-kd branched PEG molecule. It is predominantly metabolized by the liver. It has immunomodulatory actions; intralesional administration is more effective than systemic administration and is associated only with mild flulike symptoms. Treatments may be required for several weeks to months before beneficial results are seen. Consider this treatment as third line, and reserve it for warts resistant to standard treatments.
5-Fluorouracil is a topical chemotherapeutic agent that is approved to treat actinic keratoses and superficial basal cell carcinoma; it has been found to be more successful in the treatment of flat warts than plantar and common warts. Apply a 5% solution or cream daily for up to 1 month; it may be used under occlusion, but the risk of irritation increases.
Antibiotic antineoplastics inhibit cell growth and proliferation.
Bleomycin is a cytotoxic polypeptide that inhibits DNA synthesis in cells and viruses. It has affinity for HPV-infected tissue and induces vascular changes that result in epidermal necrosis. Bleomycin has been beneficial in treating resistant warts. Reserve this as a third-line treatment when standard therapies have failed. Inject 0.5-1 U/mL solution directly into the wart, not to exceed 1.5 U/treatment; less painful administration involves placing 1 mg/mL gtt onto wart and pricking it into the wart with a needle.
Histamine H2 receptor antagonists
These type 2 histamine receptor antagonists are commonly used to treat peptic ulcer disease; owing to their immunomodulatory effects at higher doses, they have been used as treatment for warts. Results have been variable, and double-blinded, placebo-controlled studies have shown no benefit.
Cimetidine is believed to have immunomodulatory effects at higher doses. It may be administered at 20-40 mg/kg PO qd divided q6h, not to exceed 2400 mg/day.
Retinoidlike agents may be helpful in immunocompromised patients with extensive disabling hyperkeratotic warts. They may help alleviate pain and facilitate the use of other treatments. In addition, retinoids have helped reduce the number of lesions in immunosuppressed renal transplant patients. Topical retinoids may be useful in treating flat warts.
Isotretinoin is a synthetic 13-cis isomer of the naturally occurring tretinoin (trans -retinoic acid); it is structurally related to vitamin A. It is approved for severe nodular acne but has also been helpful in certain keratinization disorders.
A US Food and Drug Administration–mandated registry is now in place for all individuals prescribing, dispensing, or taking isotretinoin. For more information on this registry, see iPLEDGE. This registry aims to further decrease the risk of pregnancy and other unwanted and potentially dangerous adverse effects during a course of isotretinoin therapy. It may be administered at 0.5-2 mg/kg/d PO divided bid with food.
Topical Skin Products
Products that become cytotoxic following exposure to light may be beneficial.
5-Aminolevulinic acid topical 20% solution is a topical porphyrin available as Levulan Kerastick. It is to be applied topically to warts and kept under occlusion for 5 hours and then exposed to red light-emitting diodes or another suitable red or blue light source.
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