Silymarin, Doxycycline Combination Therapy Outperforms Silymarin Monotherapy for Treatment of Acne Vulgaris

According to study data published in Dermatologic Therapy, silymarin monotherapy was a less effective acne treatment than silymarin combined with doxycycline or doxycycline monotherapy. However, silymarin was well-tolerated and may remain a therapeutic option for some patients with acne.

This randomized controlled trial enrolled 60 patients aged 14 to 45 years with acne vulgaris at 2 hospitals in Tehran, Iran. Patients were randomly assigned to the following study arms: (1) 140-mg silymarin tablet once daily (n=17); (2) 140-mg silymarin tablet and 100-mg doxycycline capsule once daily (n=17); or (3) 100-mg doxycycline capsule once daily (n=16). The treatment period was 2 months, with study assessments conducted at baseline and monthly thereafter. The Global Acne Grading System (GAGS) and Acne Severity Index (ASI) were used to capture improvements in acne symptoms.

Of 60 initial enrollees, 50 patients completed treatment (80% women). Baseline disease severity was higher among patients with a family history of acne (P =.05). The greatest numerical reduction in GAGS score was observed in the combination therapy group, though between-group differences were not statistically significant. At 2 months, combination therapy was associated with greater mean (± standard deviation [SD]) ASI score reduction compared with silymarin monotherapy (−38.58 ± 21.20 vs −24.47 ± 21.3; P =.016) but not doxycycline monotherapy (−38.58 ± 21.20 vs −35.34 ± 16.56; P =.9). Doxycycline monotherapy was also more effective than silymarin monotherapy (−35.34 ± 16.56 vs −24.47 ± 21.39; P =.02).

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No major adverse events were observed in any treatment group, although 2 patients reported digestive issues while taking doxycycline.

Greatest improvement per the ASI was seen with doxycycline, whether as monotherapy or in combination with silymarin. In the GAGS index, however, silymarin performed similarly with doxycycline treatment modalities.

The small sample size and short treatment period may limit data generalizability.

Further study in a larger cohort size is necessary to identify the full therapeutic effect of silymarin. “The results of our study suggest that, although the silymarin monotherapy is not as effective as doxycycline for the treatment of acne vulgaris, it can be a therapeutic option,” investigators wrote.  

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Shie Morteza M, Hayati Z, Namazi N, Abdollahimajd F. Efficacy and safety of oral silymarin in comparison with oral doxycycline and their combination therapy in the treatment of acne vulgaris [published online October 3, 2019]. Dermatol Ther. doi:10.1111/dth.13095