Osthol is a natural coumarin compound primarily isolated from the plant Cnidium monnieri. Scientific interest in osthol’s potential for psoriasis stems from preclinical studies demonstrating its anti-inflammatory, immunomodulatory, and antiproliferative effects. In the context of psoriasis—a chronic inflammatory skin disorder characterized by hyperproliferation of keratinocytes and immune dysregulation—these properties are considered relevant therapeutic targets.

Several in vitro and animal model studies have shown that osthol can inhibit inflammatory mediators such as TNF-α, IL-6, and IL-1β, all of which are implicated in the pathogenesis of psoriasis. For example, a 2020 study in Phytomedicine reported that osthol suppressed the proliferation of human keratinocytes and reduced skin inflammation in a mouse model of psoriasis-like dermatitis. Osthol has also been shown to modulate signaling pathways involved in psoriasis, including the NF-κB and MAPK pathways.

Despite these promising findings, there is a lack of robust clinical trials evaluating osthol’s efficacy and safety in human patients with psoriasis. As such, the scientific evidence is currently limited to preclinical studies, and its use for psoriasis cannot yet be endorsed by high-level clinical data.