The black walnut leaf has been used for medicinal purposes for centuries. Pliny, a Roman natural philosopher, mentions its use in healing as far back as the first century AD. It's botanical name, Juglans, comes from the Latin name of the god Jupiter and glans, or walnut. In the Golden Age, walnuts were considered a food fit for the gods. Nicholas Culpepper, a 17th century herbalist, prescribed black walnut leaf to draw venom from snakebite and spider bites. Native Americans used black walnut leaf as a laxative and to cure skin disorders. Black walnut jam was an early vitamin supplement due to its high content of vitamin C, beta-carotene, and minerals.
Modern herbal practitioners prescribe black walnut leaf for many reasons. Because it is a powerful astringent, it is used to shrink sweat glands and control excessive sweating. It is also used to treat and control diarrhea and the excessive loss of blood during menstruation.
It is effective against head colds and sinus infections and has been used in Germany for this purpose. As an antifungal, it is believed to be effective against yeast infections, athlete's foot, impetigo, and leprosy-like skin infections. It can also be used to treat dandruff. Black walnut leaf has astringent, antibacterial, antiseptic, and detergent properties. It is useful in the treatment of acne, psoriasis, and eczema, and has anti-itch properties as well. As a vermifuge, it has been found effective against ringworm, tapeworm and other parasites. Historically, it has been used to fight poison, venomous bites, bites by rabid dogs, gangrene, and boils. There is some evidence that it has anti-tumor properties.
Black walnut leaf can be used as a tea, infusion, or decoction. It can be applied topically or taken as a tonic. There are no known side effects or interactions, although some people may experience mild dermatitis if taken for an extended period of time. Black walnut leaf is not intended for prolonged use.