To the Editor:

The review by Dr. Frazier and colleagues on the varied presentations of rosacea and the many treatments available is excellent.¹ I would like to mention an additional treatment for rosacea that is safe, effective, and economical. Patients with rosacea often have small intestinal bacterial overgrowth (SIBO) as a second diagnosis. SIBO occurs when there is excessive bacterial growth in the small intestine, usually defined as more than 10⁵ colony-forming units per mL in a jejunal aspirate. However, most clinicians now use a home SIBO breath test for diagnosis. In patients with SIBO, the prevalence of rosacea is approximately 10 to 12 times the prevalence in matched control patients. In 2008, Parodi and colleagues studied a series of 56 patients who had both rosacea and SIBO.² Subsequently, a randomized trial was performed in which 28 patients in the active arm were treated with rifaximin, whereas the remaining patients received placebo. The authors reported that eradication of SIBO induced an almost complete regression of cutaneous rosacea lesions. In the active arm of the trial, 78% of patients had complete clearance of their skin lesions, whereas 17.7% of patients were greatly improved. In addition, 96% of patients who achieved remission remained symptom-free for at least 9 months, and 65% remained in remission after 3 years.³

This study’s findings support screening patients who have rosacea with a home breath test for SIBO and treating those who test positive with a course of rifaximin.

In Reply:

Thank you for your letter highlighting the association between small intestinal bacterial overgrowth (SIBO) and rosacea. The relationship between gut dysbiosis and cutaneous pathology is an exciting area of research with the potential for developing new therapies to benefit patients with rosacea. However, our literature review found a lack of conclusive evidence regarding the precise role of gastrointestinal disorders in rosacea, including the potential role of SIBO.

A multitude of trials describe the implications of disruptions in the gut-skin axis, including an association with rosacea.¹ The link between gut dysbiosis and rosacea is thought to be due to disturbances of the intestinal mucosal layer.² These processes can allow pathologic substances from the gut to infiltrate the bloodstream, dysregulating systemic inflammatory and immune responses, and consequently disrupting cutaneous physiology. As discussed in our article, rosacea pathogenesis is linked to impaired and exaggerated inflammatory, immune, and vascular responses. This systemic immunity impairment caused by impaired gut permeability may contribute to the development of rosacea and the exacerbation of rosacea symptoms.

The strongest evidence of gut dysbiosis and its relationship with rosacea exists with Helicobacter pylori infection.³ We could not find high-quality evidence linking SIBO and rosacea, nor examining the impact of treating SIBO on rosacea activity. The studies mentioned in your letter have small sample sizes, and we have concerns about the methodology. The patients were enrolled from a single institution, which is problematic because there are significant geographic differences in the prevalence of SIBO.⁴ Further, the diagnosis of SIBO is nuanced, with newer data suggesting the breath tests used in these studies result in unacceptably high false-positive rates.⁵

We recommend against screening patients with rosacea for SIBO using breath tests given the inconclusive relationship between SIBO and rosacea and the diagnostic limitations of these tests. Although the rifaximin therapy appears to be promising, we cannot support its use in patients with rosacea as a primary therapy without evidence of another indication.