Rheumatoid arthritis (RA) is characterized by chronic synovitis with pannus formation and progressive joint destruction. Pannus growth relies on angiogenesis, and nitric oxide (NO) contributes to vascular and inflammatory signaling. Although Pelargonium sidoides (PS) has not been evaluated in experimental arthritis, prior work suggests that PS can modulate NO production in activated macrophages. Arthritis was induced with comp...