What is Arnica Blue? A Cooling and soothing topical herbal gel to aid relief of aches, pains and stiffness of muscles and joints associated with sprains & strains. How does Arnica Blue work? Arnica Blue has 4 main ingredients that work together to help provide relief: Arnica oil – A Popular herbal remedy for both bruising and soft tissue injury. Camphor – Traditionally used as an aid to mobility. Menthol – Stimulates the sensory nerves, inducing a feeling of coolness and is also known to relive itching. Witch hazel – Used mainly to promote the natural healing of bruises.