Hairy Arnica (Arnica mollis, closely related to Arnica montana) has a long history of traditional use among Native American populations and in various folk medicine practices for treating external ulcerations, wounds, and skin inflammations. The use of arnica preparations—typically as poultices, ointments, or infusions applied directly to the affected area—was believed to promote healing, reduce inflammation, and prevent infection.

The primary justification for Hairy Arnica’s use in external ulcerations is rooted in traditional knowledge rather than modern scientific validation. Historical ethnobotanical records document its application for skin sores, bruises, and ulcers. The plant contains sesquiterpene lactones, flavonoids, and essential oils, which are thought to contribute to its anti-inflammatory and antimicrobial properties. However, most scientific studies have focused on Arnica montana, not specifically Hairy Arnica (Arnica mollis), and even for A. montana, conclusive clinical evidence for efficacy in ulcer treatment is limited.

While some laboratory studies indicate potential anti-inflammatory and antibacterial actions, rigorous clinical trials substantiating the safety and effectiveness of Hairy Arnica for external ulcerations are lacking. Thus, its continued use for this condition is primarily based on traditional practice rather than robust scientific proof.