Hydrogen Peroxide Topical Solution, 40% (w/w) for the Treatment of Seborrheic Keratoses

A Review

Emily C. Murphy, BS; Adam J. Friedman, MD


Skin Therapy Letter. 2020;25(1):1-4. 

In This Article

Adverse Effects of HP40

In the phase 3 trials, 21% of the HP40 group and 19% of the vehicle group reported adverse effects; most were mild to moderate and all were limited to local skin reactions.[20] Three events related to HP40 were considered severe: application site pain, a burn from treatment, and a burning sensation. Ten minutes after HP40 application, erythema was observed in 91% of SKs and edema in 75% of SKs. By day 106, the percentage of HP40-treated SKs with erythema decreased to 10.1% and no SKs exhibited edema. Other symptoms at day 106 included scaling (8.0%), hyperpigmentation (7.8%), crusting (5.4%), hypopigmentation (3.0%), scarring (<1%), and erosion (<1%).[20] Examining skin reactions by anatomic location, Smith et al. found that SKs on the face showed the lowest rates of hyperpigmentation (2.3% versus 10.8% trunk, 6.9% extremities), hypopigmentation (1.9% versus 3.5% trunk, 3% extremities), and scarring (0% versus 0.6% trunk, 1% extremities).[22]

While the risks of pigmentary changes and scarring at day 106 were low, especially for facial SKs, 98.8% of the study sample were FST I-IV, with only 7.3% having FST IV, so the effects on patients with FST IV or higher could not be adequately assessed.[20] A study by Kao et al. used an ex vivo model of human FST V skin to explore the toxicity of HP40 (1 and 2 μL) compared to cryotherapy (5- and 10-second cycles).[23] A colorimetric MTT assay was used to measure overall cytotoxicity and S100 stained-melanocytes were quantified to assess melanocyte toxicity. The authors found that HP40 was less cytotoxic overall and to melanocytes compared with cryotherapy, meaning that HP40 may cause less pigmentary changes in patients with dark skin.[23] However, clinical trials comparing the adverse effects of HP40 and cryotherapy are needed before conclusions can be drawn. Given hyperpigmentation was seen in 8% of HP40-treated SKs[20] and patients with darker skin are more prone to pigmentary changes,[7] HP40 should be used cautiously in FST IV-VI patients until further research is done.