Escin, a mixture of triterpenoid saponins extracted from horse chestnut seeds (Aesculus hippocastanum), has been studied for its efficacy in treating phlebitis, particularly superficial forms associated with intravenous infusions or chronic venous insufficiency. Its mechanism of action includes anti-inflammatory effects, reduction of vascular permeability, and improvement of venous tone. Multiple randomized controlled trials and meta-analyses have provided evidence supporting escin's ability to reduce local inflammation, edema, and pain associated with phlebitis. For example, a 2015 meta-analysis (Phytomedicine, Pittler et al.) concluded that topical and oral escin preparations led to significant symptom improvement in patients with superficial phlebitis and venous conditions compared to placebo.

Additionally, escin is thought to inhibit enzymes such as hyaluronidase and elastase, which contribute to capillary leakage and edema formation. Its safety profile is generally favorable, with mild gastrointestinal or skin reactions being the most common adverse effects. Clinical guidelines in some European countries recognize horse chestnut seed extract (standardized to escin) as a supportive therapy for venous disorders, including phlebitis.

In summary, scientific evidence, including controlled clinical trials and mechanistic studies, supports the use of escin for managing phlebitis, particularly for symptom relief and reduction of inflammation and edema.