The Role of Gut and Skin Microbiota in Alopecia Areata

The goal of this clinical trial is to learn if fecal microbiota transplantation (FMT) works to treat alopecia areata in adults. It will also learn about the safety of FMT. The main questions it aims to answer are: * Can FMT cause hair regrowth? * Can FMT modulate immune response? Researchers will compare FMT to a placebo (a look-alike substance that contains no drug) to see if FMT works to treat alopecia areata. Participants will: * Take FMT or a placebo for three consecutive days * Follow-up evaluations will be performed at weeks 12, 24, and 48, with repeat clinical scoring, photodocumentation, microbiome analyses, laboratory testing, and quality-of-life assessment.