Herbal Monograph: Black Walnut 

Botanical Name: Juglans nigra

Common Names: Black Walnut, Eastern Black Walnut

Family: Juglandaceae

 

Plant Description:

Black walnut is a large, deciduous tree native to North America, typically reaching 50–75 feet in height. It has deeply furrowed bark, compound leaves with 15–23 leaflets, and produces round, green husked fruits that contain a hard, dark brown nut. The tree prefers rich, well-drained soil and is commonly found in forests, along riverbanks, and in open woodlands.

Parts Used:

• Hulls (green/fresh and dried/black/brown)

• Bark

• Leaves

• Nuts

Active Constituents:

• Juglone (a natural antifungal and antibacterial compound)

• Tannins

• Flavonoids

• Essential fatty acids

• Vitamin C

Energetics/Taste:

• Taste: Fragrant Bitter, astringent, alterative

• Energy: Cooling, drying

Tissue States​

• Depression

• Relaxation

• Torpor

​Doctrine of Signatures:

• Suggestive of expelling/expulsion properties. 

• Protection and abundance

• Liminal or Transition Plant/Space

  • They often are found in riparian zones which are the edge spaces between streams/rivers and the land​

Traditional and Modern Uses:

• Antiparasitic: Traditionally used to expel intestinal parasites and worms.

• Antifungal: Effective against Candida and other fungal infections.

• Skin Health: Used externally for eczema, ringworm, and acne.

• Digestive Support: Aids digestion and supports liver function.

• Oral Health: Used as a mouth rinse for gum infections and sores.

• Circulatory Health: Considered a blood purifier and may support cardiovascular health.

     Parts of the Plant Used:

• Inner Bark:

  • Cathartic, fibrin solvent (potassium sulphate), muscle and nerve food (magnesium sulfate), food for hair, skin, nails, nerve sheaths, and periosteum (silica).

  • Can make a laxative tea with the bark, but bark also contains chemicals that can be poisonous/toxic if consumed in large quantities. A wineglass full can be given to start and increased to decreased to bring about a soft molded stool 2-3 times a day. 

• Leaves​

  • Internal

    • Effective against Helicobacter pylori (H. pylori)/some gastrointestinal ulcers

    • “Vasocompression is the term used [by Dr. Joseph Thurston] to describe the ability of a medicine to constrict the tissue, thereby supporting improved muscle tone, mucous membrane, and blood vessel. Compressing tissue improves blood vessel tone and ultimately blood supply to that organ.”

      • These remedies are therefore suited to inflammatory conditions of the mucosa, vessels, and skin, chronic inflammation of the throat from intestinal toxemia (tonsillitis), and dry, congested, and irritated mucosa. Juglans spp. “gently tones the intestinal wall if given over time.

    • Stimulates lower bowel clearance, this encourages the portal system to decongest. Chronic constipation, waterbrash, and flatulence. Cleanses and tones the colon, prevents uptake of toxins from constipated bowels “Leaky bowel syndrome” today, and can treat malabsorption from a closed gut, colitis, diarrhea, dysentery, hemorrhoids/bleeding hemorrhoids, relaxed and ballooned intestines, leucorrhea.

    • Canker sores (aphthous sore); tonsillitis, sore throat, relaxed uvula, diphtheria; hoarseness. 

    • Epistaxis, nasal catarrh. 

    • Tones the vascular system and helps assimilation of nutrients (fats and proteins) and reduces unhealthy fatty acids in the blood- improving the vascular system and the heart (helps with high cholesterol)/ Arteriosclerosis, fatty deposits, venous congestion (varicose veins)

    • Help to reduce excessive sweating. The high levels of astringent tannins contained in the hulls are believed to have an effect on overactive sweat glands and decrease the amount of sweat they produce.

  • External:  

    • Ulcers, tumors, cancers, abscesses, boils, acne, eczema, itch, shingles, and so forth.

    • Skin conditions: Ringworm, falling hair, eczema, itch, shingles, tumors, cancers, abscesses, boils, acne (external). 

    • Powdered Leaves can be used on moist skin disease, bleeding

• Walnut Hulls

  •  Internal

    • Conditions where there is a combination of intestinal and skin problems suggesting the participation of low forms of life.
      Low thyroid, low metabolism, “bad blood.” Swellings on the thyroid—that is, goiter. Alternative treatment for thyroid problems (goiter, hypothyroid (hull and chickweed tincture))
      Irritation of the mucosa. 

    • Jaundice; pain around the liver and right scapula. Duodenal catarrh, with torpid liver and jaundice. Congestion of the gallbladder; gallstones.

    • Diarrhea, constipation, parasites. Irritability and inflammation of the intestines; worms. Diarrhea from drinking bad water (combine with Capsicum), Valley fever.

    • Rheumatism (fibromyalgia – which is a common characteristic of hypothyroidism) and arthritis, swollen hands
      Iodine important for breast health, in which deficiency can lead to fibrous breast disease and cancer
      Keep sinuses in good health/sinusitis as many sinus infections are r/t fungal infection
      Treat an athlete’s foot.

    • Additionally, the tannins present in black walnuts may help reduce excessive sweating, aid digestion, relieve heartburn, and treat skin conditions like acne and boils. 

  • External

    • Skin conditions; impetigo, eczema, herpes, shingles, cold sores, acne, pemphigus, rupia, athlete’s foot, lichen, ringworm, rashes, chronic scaly skin conditions, especially when associated with intestinal disorder. Skin eruptions red, like the flush of scarlatina or erysipelas (cf. Stellaria). Abscesses, boils. 

Preparation and Dosage:

• Tincture of Walnut Hulls: Varying doses 

  • 1-3 drops 1-3x a day

  • 2–4 mL, 2–3 times per day (1:5 in 40% alcohol)

  • Boil 1/4 teaspoon salt in 1c water and add 30drops of black walnut tincture. Let sit 25 min and run through sinus passages with a neti pot.

  • **WEEKLY MAX 10-15ml

    • Pause dosing​: 2 weeks on, 2 weeks off

• Decoction:

  • 1 teaspoon of dried hulls per cup of water, simmered for 10–15 minutes, taken up to 3 times daily.

  • ​

• Topical:

  • Infused oil or poultice applied to affected skin areas.

• Powdered Hulls:

  • 500–1000 mg in capsules, taken daily for parasitic infections (short-term use only).

  • Hull powder can be used on skin that is prone to moist/yeasty growth

Alternative Uses:

• Food/Drink Options:

  • Eat the walnuts. One the hull is removed and the walnut is cleaned, leave to cure/dry for several weeks. Can store in their shell longer. Once cracked, the high oil content will cause them to turn rancid quickly. Otherwise, you can store cracked walnut meat in a mason jar in the freezer.

  • Can make a laxative tea with the bark, but bark also contains chemicals that can be poisonous if consumed in large quantities. A wineglass full can be given to start and increased to decreased to bring about a soft molded stool 2-3 times a day. The toxin can be avoided by brewing tea with the nut-meat. Walnut tea can be brewed along with rice and dates, and is a popular drink

  • Green walnut hulls can be used to make a black walnut liquor (Nocino). This recipe is traditionally made in June or July and steeped for 6 months, then enjoyed around Christmas

  • Syrup from the sap of the tree (recommended trees with 14” diameter or greater)

  • Green black walnut Honey/syrup from the immature green walnut hulls (smaller than a ping pong ball) fermented for at least 30 days, then boiled, strained and stored. Can last years and should be refrigerated once opened.

• Walnut oil- great for cooking and sealing wood 

• Dye or ink from powder that can be used to stain wood, dye cloth/fabric/yarn, or an ink to paint/write with

Safety and Precautions:

• Not recommended for long-term use due to its strong purgative and astringent effects.

• Avoid use during pregnancy and lactation.

• May cause gastrointestinal irritation in high doses.

• Juglone can be toxic in high concentrations; use with care.

• Potential allergen—people sensitive to nuts should use caution.​

Contraindications:

• Individuals with nut allergies should avoid use.

• May interfere with certain medications, including blood thinners.

• Chronic GIT conditions

• Pregnancy/lactation.

Toxicity:

Nausea/vomiting, watery catharsis, external application may cause dermatitis (treat by washing area with soap and water). Juglone may cause allergic reaction and genetic mutation with long term use

Sustainability and Ethical Considerations:

Black walnut trees play a vital role in their ecosystems. Due to their allelopathic nature (juglone inhibits the growth of some plants), they should be planted thoughtfully. Sustainable harvesting practices should be observed, particularly with hulls and bark, to avoid damage to wild populations.

Conclusion:

Black walnut (Juglans nigra) is a potent botanical with a long history of medicinal use. Its powerful antifungal, antiparasitic, and astringent properties make it a valuable herbal ally. However, due to its strength, it should be used with care and respect.

References:

• Bergo A. Green Walnut Molasses. Forager | Chef. Published July 10, 2021. Accessed October 9, 2023. https://foragerchef.com/green-walnut-honey/#recipe 

• Black Walnut Benefits. Indigo Herbs. https://www.indigo-herbs.co.uk/natural-health-guide/benefits/black-walnut  

• O’Driscoll D. Sacred Tree Profile of Walnut (Juglans Nigra): Magical, Medicinal, and Edible Qualities. The Druids Garden. Published November 6, 2016. Accessed October 9, 2023. https://thedruidsgarden.com/2016/11/06/sacred-tree-profile-of-walnut-juglans-nigra-magical-medicinal-and-edible-qualities/ 

• Page T. 14 Uses for Black Walnuts. Homestead Honey. Published December 19, 2021. Accessed September 9, 2023. https://homestead-honey.com/uses-for-black-walnuts/ 

• Wood M. The Earthwise Herbal : A Complete Guide to New World Medicinal Plants. Berkeley, Calif. North Atlantic Books; 2009.

• Dr. Marisa Marciano, ND. Juglans nirgra/Black Walnut. Accessed February 16, 2025. https://thenaturopathicherbalist.com/herbs/i-l/juglans-nigra-black-walnut/