Wound Care After Cantharidin Treatment
After cantharidin application, keep the treated area clean and dry with a clean, dry bandage covering the blister site, monitor daily for signs of infection, and expect temporary pain, burning, or tenderness for 2-4 days that resolves without intervention. 1, 2, 3
Immediate Post-Treatment Care (First 24-48 Hours)
- Cover the treated area with a clean, dry bandage immediately after application to protect the developing blister and minimize infection risk. 1, 4
- Keep the wound completely dry during the first 24-48 hours to allow proper blister formation and initial healing. 4
- Avoid submerging the treated area in water; brief showers may be acceptable after 24 hours if the area can be kept dry. 4
- Maintain strict hand hygiene with soap and water or alcohol-based hand sanitizer before and after touching the treated area or changing dressings. 1, 4
Expected Blister Formation and Pain Management
- Blistering occurs at the application site in approximately 92% of patients and is the intended therapeutic effect. 3
- Temporary burning, pain, erythema, or pruritus occurs in 6-37% of patients and typically lasts 2-4 days. 2, 3
- Pain can be avoided or minimized by careful, precise application limited only to the lesion itself. 2
- No specific pain medication is typically required, as discomfort is self-limited and mild in most cases. 3
Daily Wound Monitoring Protocol
- Inspect the treated area daily for signs of infection: increasing pain (beyond the expected 2-4 day period), expanding redness, swelling, warmth, purulent discharge, or foul odor. 1, 4, 5
- Change dressings daily while performing inspection to maintain cleanliness and assess healing progress. 1, 4
- Monitor for wound edge separation or opening, which would require immediate medical attention. 4, 6
- Watch for red streaks extending from the treated site, which indicates spreading infection requiring urgent evaluation. 1, 4
Activity Restrictions
- Avoid activities that place tension on the treated area or cause excessive sweating for at least the first week. 4, 6
- Elevate the treated body part if swelling occurs to accelerate healing. 4, 6
- Avoid reusing or sharing personal items (towels, clothing) that have contacted the treated area. 1, 4
Management of New Warts at Blister Edge
- Occasionally new warts appear at the edge of the cantharidin blister as a recognized complication. 2
- These edge lesions are best treated by curettage and desiccation rather than repeat cantharidin application. 2
Warning Signs Requiring Immediate Medical Attention
- Fever or chills suggesting systemic infection. 4
- Red streaks extending from the wound indicating lymphangitis. 1, 4
- Pus or cloudy drainage from the blister site. 4
- Wound edges separating or opening beyond expected blister formation. 4, 6
- Pain that increases after the first 2-4 days or is disproportionate to the expected discomfort. 4, 2
- Foul odor from the treated area suggesting bacterial superinfection. 4
Critical Pitfalls to Avoid
- Do not apply ointments, creams, or lotions over the treated area, as these interfere with proper blister formation and healing of the lesion. 4
- Do not leave the treated area uncovered, as this increases infection risk and delays healing. 4
- Do not attempt to drain or puncture the blister, as this is part of the therapeutic mechanism. 3
Expected Treatment Course
- Most lesions clear after a single application (56% of digital warts, 33% of periungual warts in one study). 2
- Re-treatment at weekly intervals may be needed until clinical cure is achieved, with few requiring more than three treatments. 2
- Overall clearance rate is approximately 90% with an average of 2.1 treatment visits. 3
- No cases of secondary bacterial infection have been reported with proper application technique in large pediatric series. 3
- No scarring occurs with proper use by a physician, making this particularly advantageous compared to other destructive modalities. 2, 7