In‐vivo anti‐inflammatory activity of silymarin was tested in different acute inflammation experimental models.

In carrageenan‐induced paw oedema in rats, silymarin given orally reduced in a dose‐dependent manner the food‐pad abscesses (ED50 = 62.42 mg kg⁻¹). In xylene‐induced ear mouse inflammation, silymarin applied topically was more effective than administered intraperitoneally, with effects comparable with those of indomethacin. Silymarin also produced a dose‐dependent inhibition of leukocyte accumulation in inflammatory exudates following intraperitoneal injection of carrageenan in mice; silymarin significantly reduced the number of neutrophils. Silymarin was unable to inhibit phospholipase A₂ in an in‐vitro assay.

Besides its known anti‐oxidative properties and its ability to act as a radical scavenger, these results suggest that silymarin exerts an important anti‐inflammatory action in‐vivo by reducing oedema with the effect markedly influenced by the inhibition of neutrophil migration into the inflamed site.