Glycolic Acid as a Treatment for Warts?

Genital warts, plantar warts, flat warts, common warts... these skin warts are small benign growths that come in various shapes, colours, and sizes. They appear when the epithelial cells of the basal layer are infected by one of the many viruses from the Papillomavirus human (HPV) family. Although they can develop anywhere on the body, they are more likely to appear on the face, hands or feet.

Whilst the majority of warts typically undergo spontaneous remission within a few months or even years without any treatment, patients may seek treatment due to discomfort, aesthetic concerns, social rejection, spread, persistence, recurrence, or worries about transmission. Among the destructive chemical (trichloroacetic acid peeling, sulphur, retinoids, etc.) and physical (electrocautery, cryotherapy, etc.) wart therapies, this includes the topical application of glycolic acid where some have shown it to be capable of accelerating their resorption.

• In a study from 2000, 15 children aged between 5 and 11 years old, who had flat warts in the facial region, were treated by daily application of a 15% glycolic acid gel over the entire area where the warts were located for two months. The warts disappeared in 14 patients, in less than 4 weeks in 5 patients (33%) and before 8 weeks in 9 patients (60%).

• A further study from 2011 assessed the effectiveness of a topical gel containing 15% glycolic acid and 2% ofsalicylic acid on 20 participants aged between 7 to 16 years old suffering from flat warts on the face. The study demonstrated that the gel worked extremely well, resulting in complete remission in all 20 patients after four to eight weeks of treatment.

• A 2012 study tested the efficacy of a 15% glycolic acid lotion in 31 HIV-positive children suffering from flat warts, primarily on the face and the back of the hands. After 16 weeks, the results indicated that the treatment managed to flatten and normalise the colour of the warts, but it only completely eliminated them in 3 participants (10%).

• In a 2017 study, MOCHIZUKI T. & co. reported the complete disappearance of plantar warts in six patients aged between 7 and 34 years following the application of a 25, 35 or 50% glycolic acid solution one to three times a day for several weeks. However, for four of these cases, an additional treatment (cryotherapy, powdered coix seeds) was administered, which could potentially compromise the results.

• A 2017 study reported the case of a 30-year-old man suffering from widespread flat warts on the face, treated with a 35% aqueous solution of glycolic acid. The wart-like lesions almost completely disappeared after six peeling sessions every two weeks.

• In a clinical trial, the effectiveness of a 35% glycolic acid chemical peel was evaluated in 30 patients with flat warts on the face. After three peels applied every fortnight, 50% of the patients (15 out of 30) achieved a 70% reduction in lesions, whereas the other side of the face treated daily with an adapalene gel (control) showed an improvement in facial warts in eight patients (27%).

• A comparative therapeutic trial was conducted on 60 patients suffering from flat warts, with the aim to evaluate the effectiveness of 30% salicylic acid chemical peels compared to a 70% glycolic acid solution. After the completion of six peel sessions every two weeks, a significant reduction in the number of warts was observed in patients treated with a 30% salicylic acid solution compared to those who received a 70% glycolic acid solution. The use of 30% salicylic acid proved to be more effective and with a quicker response, compared to the 70% glycolic acid solution.

Glycolic acid chemical peeling could thus be an effective option for treating warts. However, although the results are promising, these seven studies were conducted on small samples. Therefore, additional research is necessary to confirm these findings.

While there are many types of warts, glycolic acid has particularly demonstrated its effectiveness on flat warts according to the various scientific evidence available to date.

By what mechanism?

It has been suggested that at high concentrations (>20%), glycolic acid would act by damaging and destroying the infected epithelium due to its keratolytic abilities. Indeed, it reduces the cohesion between keratinocytes by interfering with ionic bonds, thus leading to the detachment of epidermal cells. However, further work and studies are necessary to establish the mechanism of action of glycolic acid peeling in the treatment of warts.