Black Walnut

Reviewed on 6/11/2021
Other Name(s):

Carya, Carya basilike, Carya persica, Green Black Walnut, Green Walnut, Juglans nigra, Jupiter's Nuts, Nogal Americano, Nogal Negro, Nogueira-preta, Noix, Noix de Jupiter, Noix de Perse, Noix Verte, Noyer d’Amérique, Noyer Noir, Noyer Noir Américain, Nux persica, Nux regia, Schwarze Walnuss, Walnoot, Walnut.


Black walnut is a tree. People use the outer covering of the nut (the hull) to make medicine.

Black walnut is used to treat parasitic worm infections and certain other infections including diphtheria and syphilis. It is also used for leukemia.

Some people use black walnut as a gargle, apply it to the scalp as hair dye, or put it on the skin to treat wounds.

How does it work?

Black walnut contains high concentrations of chemicals called tannins, which can reduce pain and swelling and dry up body fluids such as mucous.


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Uses & Effectiveness

Insufficient Evidence to Rate Effectiveness for...

  • Leukemia.
  • Diphtheria.
  • Syphilis.
  • Intestinal worms.
  • Use as a gargle.
  • Skin wounds.
  • Other conditions.
More evidence is needed to rate the effectiveness of black walnut for these uses.

Natural Medicines Comprehensive Database rates effectiveness based on scientific evidence according to the following scale: Effective, Likely Effective, Possibly Effective, Possibly Ineffective, Likely Ineffective, and Insufficient Evidence to Rate (detailed description of each of the ratings).

Side Effects

Black walnut is POSSIBLY SAFE for most people when taken by mouth short-term. It is not known what the possible side effects from short-term use might be.

Black walnut is POSSIBLY UNSAFE when applied directly to the skin. It contains a chemical called juglone that might cause tongue or lip cancer, especially if applied daily.

Special Precautions & Warnings:

Pregnancy and breast-feeding: Don’t apply black walnut to the skin if you are pregnant or breast-feeding. This topical use is POSSIBLY UNSAFE. There is not enough reliable information about the safety of black walnut taken by mouth if you are pregnant or breast-feeding. Stay on the safe side and avoid use.


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Medications taken by mouth (Oral drugs)Interaction Rating: Moderate Be cautious with this combination.Talk with your health provider.

Black walnut hulls contain a large amount of chemicals called tannins. Tannins absorb substances in the stomach and intestines. Taking black walnut along with medications taken by mouth can decrease how much medicine your body absorbs, and decrease the effectiveness of your medicine. To prevent this interaction, take black walnut at least one hour after medications you take by mouth.


The appropriate dose of black walnut depends on several factors such as the user’s age, health, and several other conditions. At this time there is not enough scientific information to determine an appropriate range of doses for black walnut. Keep in mind that natural products are not always necessarily safe and dosages can be important. Be sure to follow relevant directions on product labels and consult your pharmacist or physician or other healthcare professional before using.

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