Introduction
Wart removers encompass a category of topical medications designed to treat cutaneous warts caused by human papillomavirus (HPV) infection. These products are available as both prescription and over-the-counter formulations, with salicylic acid being the most common active ingredient. Wart removal therapies work through chemical destruction of infected epidermal tissue and stimulation of local immune responses.
Mechanism of Action
Wart removal medications employ various mechanisms depending on their active ingredients:
Salicylic acid (17-40% concentrations): Keratolytic action that softens and breaks down hyperkeratotic tissue through dissolution of intercellular cement substance, promoting desquamation of infected epidermal cells Cryotherapy agents (dimethyl ether/propane mixtures): Produce rapid freezing (-57°C) causing cytodestruction through intracellular ice crystal formation, vascular damage, and subsequent inflammatory response Cantharidin (prescription): Blistering agent that causes acantholysis through inhibition of mitochondrial cytochrome oxidase, leading to epidermal necrosis and separation at the dermoepidermal junction Imiquimod (prescription): Immune response modifier that activates toll-like receptor 7, stimulating production of cytokines (particularly interferon-α) that enhance cell-mediated immunity against HPV-infected cellsIndications
- Common warts (verruca vulgaris)
- Plantar warts (verruca plantaris)
- Flat warts (verruca plana)
- Periungual warts
- Mosaic warts (multiple coalescing plantar warts)
Dosage and Administration
Salicylic acid preparations:- Apply once daily to wart surface after soaking area for 5 minutes
- Carefully remove loosened tissue with emery board or pumice stone
- Avoid application to surrounding healthy skin
- Treatment duration: Typically 4-12 weeks
- Apply according to manufacturer instructions (typically 10-40 seconds per wart)
- Repeat every 2-3 weeks as needed
- Maximum 4 treatments per wart
- Physician-applied: Small amount applied to wart surface, covered with tape
- Leave on for 4-6 hours, then wash thoroughly
- Repeat every 3-4 weeks
- Apply 3 times per week before bedtime
- Leave on for 6-10 hours, then wash off
- Treatment duration: Up to 16 weeks
Pharmacokinetics
Salicylic acid:- Absorption: Minimal systemic absorption with topical application (<25%)
- Distribution: Localized to application site
- Metabolism: Hepatic conjugation
- Elimination: Renal excretion
- Half-life: 2-4 hours
- Absorption: Minimal through intact skin
- Distribution: Local tissue binding
- Elimination: Renal excretion
- Absorption: <1% systemic absorption
- Metabolism: Hepatic via CYP450
- Elimination: Primarily renal
- Half-life: Approximately 30 hours
Contraindications
- Hypersensitivity to any component of the formulation
- Diabetes mellitus with peripheral neuropathy
- Peripheral vascular disease
- Application to moles, birthmarks, or unusual warts with irregular coloration
- Use on irritated, infected, or inflamed skin
- Use on genital or facial warts (unless specifically formulated for these areas)
- Pregnancy (for certain prescription formulations)
Warnings and Precautions
- Risk of damage to surrounding healthy tissue
- Possible scarring or hypopigmentation
- Use caution in immunocompromised patients (may require longer treatment)
- Diabetic patients: Increased risk of ulceration and poor healing
- Avoid application to mucous membranes or eyes
- Do not use on bleeding warts
- Monitor for signs of secondary infection
- Some formulations may be flammable (cryotherapy systems)
Drug Interactions
- Concomitant use with other topical medications may increase irritation
- Salicylic acid may enhance systemic absorption of other topically applied drugs
- Imiquimod may potentiate effects of other immunomodulators
- No clinically significant systemic drug interactions reported with topical wart therapies
Adverse Effects
Common (≥1%):- Local erythema
- Burning sensation
- Pruritus
- Pain at application site
- Skin irritation
- Blister formation (with cantharidin or cryotherapy)
- Peeling or scaling
- Severe local reactions
- Hypersensitivity reactions
- Secondary bacterial infection
- Scarring
- Permanent hypopigmentation or hyperpigmentation
- Nail damage (with periungual application)
Monitoring Parameters
- Visual inspection of treatment area for response and adverse effects
- Assessment of pain or discomfort
- Signs of secondary infection (increased redness, swelling, pus)
- Evaluation for resolution of wart
- Monitoring for recurrence after treatment
- In diabetic patients: Regular foot examinations
Patient Education
- Use precisely as directed, avoiding surrounding healthy skin
- Soak wart in warm water for 5 minutes before application
- Remove dead skin with emery board or pumice between treatments
- Wash hands thoroughly after application
- Do not share medication or application devices
- Expect mild redness and irritation; discontinue if severe pain or swelling occurs
- Protect treated area from excessive moisture
- Complete full course of treatment even if wart appears resolved
- Seek medical attention if no improvement after 12 weeks or if wart spreads
- Keep all follow-up appointments as recommended
- Store medications away from children and heat sources
References
1. Sterling JC, Gibbs S, Haque Hussain SS, et al. British Association of Dermatologists' guidelines for the management of cutaneous warts 2014. Br J Dermatol. 2014;171(4):696-712.
2. Lipke MM. An armamentarium of wart treatments. Clin Med Res. 2006;4(4):273-293.
3. Bacelieri R, Johnson SM. Cutaneous warts: an evidence-based approach to therapy. Am Fam Physician. 2005;72(4):647-652.
4. Kwok CS, Gibbs S, Bennett C, et al. Topical treatments for cutaneous warts. Cochrane Database Syst Rev. 2012;(9):CD001781.
5. FDA OTC Monograph for Topical Acne Drug Products. 21 CFR Part 333.
6. Habif TP. Clinical Dermatology: A Color Guide to Diagnosis and Therapy. 6th ed. Elsevier; 2016.
7. Wolverton SE. Comprehensive Dermatologic Drug Therapy. 4th ed. Elsevier; 2021.
8. Lexicomp Online [Internet]. Hudson, OH: Wolters Kluwer Clinical Drug Information, Inc.; 2023.