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.