A systemic antifungal medicine reduced intestinal Candida and was associated with improved gut health in a small study of people with inflammatory bowel disease and oral thrush, Weill Cornell Medicine researchers reported.
The findings suggest fungi may play a role in Crohn's disease and ulcerative colitis for some patients, but researchers cautioned that the study was not designed to prove the treatment works for IBD.
Two treatments produced different results
The study followed 53 people with mild-to-moderate Crohn's disease or ulcerative colitis who also had oral thrush. Participants received either nystatin mouthwash, which acts mainly in the mouth, or fluconazole, a systemic drug that circulates through the body.
Both treatments cleared oral thrush during the two-week treatment period. Only fluconazole significantly reduced Candida in the intestines, according to the study published Sept. 1 in Nature Medicine.
Patients who received fluconazole also showed greater microbial diversity, higher levels of the beneficial compound butyrate and lower measures of disease activity. Some changes persisted for several weeks after treatment ended.
Researchers said cheek-swab findings often reflected fungal activity in the gut. If confirmed in larger studies, that connection could offer a less invasive way to identify patients whose intestinal inflammation may be linked to Candida.
During eight weeks of follow-up, the fluconazole group had a lower probability of disease progression than the nystatin group. The researchers emphasized that the trial was small and lacked random assignment and a placebo group.
Larger controlled trial is planned
The team previously found in mouse studies that Candida can produce candidalysin, a toxin that damages tissue and promotes inflammation. The new human study was designed to explore whether reducing the fungus could affect the intestinal microbiome and symptoms.
Some immune-suppressing medicines used for IBD may also make it harder for the body to control fungal growth. Researchers said that relationship could help explain why a subset of patients develops persistent Candida in the mouth and intestine.
Fluconazole can cause side effects and interact with other medicines. The study does not support patients taking an antifungal drug without medical supervision or changing an existing IBD treatment plan.
The researchers are planning a multicenter, placebo-controlled trial to test the approach more rigorously. Future work may also include patients who do not have visible oral thrush but test positive for Candida on a cheek swab.
Inflammatory bowel disease has multiple causes and affects patients differently. The team said fungal testing and treatment, if validated, would likely apply only to a subgroup rather than replace established care.
Patients with Crohn's disease, ulcerative colitis or thrush should discuss symptoms and treatment options with a licensed health professional. The study's findings remain preliminary and are not individual medical advice.
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