Background

Black walnut (Juglans nigra) is a tree native to the US that's harvested for its wood and edible nuts. The tree bark has been used in traditional medicine.

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

People use black walnut to lower the risk of heart disease, for skin wounds, and for other conditions, but there is no good scientific evidence to support these uses.

Tree nuts, including black walnut, are considered major food allergens in the US. Don't confuse black walnut with English walnut. There are not the same.

Safety Safety definitions

When taken by mouth: The fruit (nut) of black walnut is commonly consumed in foods. But the bark is possibly unsafe. Taking the bark daily might increase the risk for tongue or lip cancer. There isn't enough reliable information to know if the leaf or the shell of the nut (hull) are safe to use as medicine. These parts of the plant contain chemicals called tannins. Taking too much tannin can cause stomach upset and kidney and liver damage.

When applied to the skin: Black walnut is possibly unsafe. It contains a chemical called juglone that can irritate the skin.

Special Precautions & Warnings:

Pregnancy and breast-feeding: The fruit (nut) of black walnut is commonly consumed in foods. But the bark is possibly unsafe. Don't take black walnut bark by mouth or apply it to the skin. There isn't enough reliable information to know if black walnut leaf or shell is safe to use when pregnant or breast-feeding. Stay on the safe side and avoid use.

Allergies to peanuts and tree nuts: People with peanut allergies are more likely to be allergic to nuts called "tree nuts." Black walnut is a tree nut. People who are allergic to one tree nut are also more likely to have an allergy to at least one other tree nut.

Effectiveness

Dosing & administration

Black walnuts are commonly consumed in foods. As medicine, there isn't enough reliable information to know what an appropriate dose of black walnut might be. 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 a healthcare professional before using.

Interactions with pharmaceuticals

It is not known if Black Walnut interacts with any medicines. Before taking Black Walnut, talk with your healthcare professional if you take any medications.

Interactions with herbs & supplements

There are no known interactions with herbs and supplements.

Interactions with foods

Black walnut contains tannins. Tannins can reduce the absorption of nutrients from foods, but it's not clear if this is a big concern.