Herb & supplement monograph

English Walnut Drug Interactions, Uses, Effectiveness, Safety & More

Medically reviewed by ·Updated July 2026
What is this page for?

First and foremost: how English Walnut interacts with medications. The heart of this page is the interaction list — every drug English Walnut is known to interact with, and how serious each one is.

But these pages have grown well beyond that into a full monograph — what English Walnut is, what people use it for and how strong the evidence is, its safety and side effects, and answers to the questions we’re asked most — written and reviewed by the clinical staff at HelloPharmacist. It’s educational information from our licensed clinical databases, not medical advice, and we don’t sell or endorse products. Our editorial policy

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Interaction report

Drugs that interact with English Walnut

0 medications have a known interaction with English Walnut, graded by severity. Select any drug for the full evidence-based detail.

We don’t currently list any known drug interactions for English Walnut. This doesn’t guarantee none exist — always confirm with your pharmacist before combining supplements with your medications.

Read The List Like a Pharmacist

What Severity, Likelihood & Evidence Mean

Severity — How Serious It Can Be

  • Major. Clinically significant; generally best avoided, or used only under direct professional supervision.
  • Moderate. May need monitoring, a dose adjustment, or separating the times you take each one.
  • Minor. Generally not clinically significant, but still worth noting and mentioning to your pharmacist.
  • No known interaction. Checked against our sources with nothing documented — not the same as proven safety.

Likelihood — How Well It’s Documented

  • Likely. Well-controlled human studies have demonstrated the likely existence of this interaction
  • Probable. Interaction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports.
  • Possible. Interaction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists
  • Unlikely. Interaction has been demonstrated in animal or in lab research but has been shown not to occur in humans.

Where This Data Comes From

  • Interaction records are evidence-graded and sourced from the Natural Medicines database (TRC Healthcare), the same reference used by pharmacists and hospitals.
  • Each drug listed above links to the full report for that exact English Walnut combination — clinical detail, likelihood, evidence level, and citations.
  • Content is reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.
Monograph

English Walnut: Uses, Safety & Side Effects

Medically reviewed by · Reviewed July 2026 ·
The bottom line

English walnut is a nutritious tree nut rich in plant-based omega-3 fats, fiber, and antioxidants, and eating it as part of a balanced diet may support heart health. Most concentrated supplement or leaf-extract uses have limited human evidence. If you have a tree nut allergy, avoid it, and check with your pharmacist before using supplements.

Scientific name
Juglans regia
Family
Juglandaceae
Part used
Nuts (kernels), leaves, and the green husks; sometimes the bark
Common forms
Whole nuts, walnut oil, capsules or softgels, leaf tea or extract
People commonly use it for
  • Heart and cholesterol health
  • Brain health
  • General nutrition (omega-3 source)
  • Antioxidant support
  • Traditional skin and digestive remedies (leaf/husk)

Popular and traditional uses — not proof it works. See “Uses & effectiveness” below for the evidence.

Safety at a glance
OverallUse caution

Walnuts are generally safe as food but can cause serious allergic reactions in people with tree nut allergies.

PregnancyLikely Safe

When the fruit (nut), leaf, or hull is consumed in amounts normally found in foods.

Read the full pregnancy detail
BreastfeedingLikely Safe

When the fruit (nut), leaf, or hull is consumed in amounts normally found in foods.

Read the full breastfeeding detail

Pregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center). Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Jump to a section

Overview

The English walnut comes from Juglans regia, a large deciduous tree that is native to parts of Asia and southeastern Europe but is now grown around the world. It is best known for its edible nut, which has a hard shell and a wrinkled, brain-shaped kernel inside.

People most often use the walnut as a food. The kernels are eaten raw or roasted, pressed into oil, or added to baked goods and salads. Beyond the kitchen, the leaves and green husks have a long history in traditional medicine, and the nuts are sometimes sold as capsules or oil for their nutritional value, especially their plant-based omega-3 fats.

How it works

Walnuts are rich in alpha-linolenic acid (ALA), a plant-based omega-3 fatty acid that the body can use to support heart and cell health. They also provide fiber, protein, vitamin E, and minerals.

The nuts and leaves contain antioxidant compounds, including polyphenols and a substance called juglone (found mostly in the husks and leaves). In laboratory and animal studies, these compounds appear to fight oxidative stress and inflammation. It is important to remember that lab and animal findings do not always carry over to people.

Effectiveness

Does English Walnut work?

Here’s what the research actually shows for each use — graded by Natural Medicines and reviewed by .

Evidence overview · 3 uses evaluated
1 Possibly effective 2 Insufficient evidence
How to read these evidence grades

Natural Medicines’ 7-point scale. We show each rating’s label word-for-word.

1EffectiveStrong, consistent evidence it works.
2Likely EffectiveGood evidence, though not yet conclusive.
3Possibly EffectiveSome evidence suggests a benefit.
4Possibly IneffectiveSome evidence it may not help.
5Likely IneffectiveFairly strong evidence it doesn’t help.
6IneffectiveStrong evidence it doesn’t work.
7Insufficient Reliable Evidence to RateToo little research to say either way.
Possibly Effective Hypercholesterolemia
Rating & evidence shown verbatim from Natural Medicines

Small clinical trials show that consuming English walnuts as part of a low-fat diet seems to lower cholesterol. Total cholesterol and lipoproteins are decreased when English walnuts are substituted for other fatty foods and constitute up to 20% of the calories in the diet. When English walnuts are added to a low fat diet, total cholesterol may be decreased by 4% to 12% and low-density lipoprotein (LDL) may be decreased by 8% to 16%. Substituting English walnuts for other dietary fats as part of a diet containing 30% fat seems to improve high-density lipoprotein (HDL) cholesterol-to-total cholesterol ratios in patients with type 2 diabetes. However, there is no effect on levels of low-density lipoprotein (LDL) cholesterol when compared with a 30% fat diet without English walnuts.

Sources Ref 6431 Ref 8476 Ref 8477 Ref 13300
Also studied for 2 conditions — evidence insufficient to rate
Insufficient Reliable Evidence To Rate Coronary heart disease (CHD)
Rating & evidence shown verbatim from Natural Medicines

Epidemiological research has found that people who increase dietary consumption of nuts in general might have a lower risk of CHD and death due to coronary events. However, there is no available evidence showing that eating English walnut, specifically, reduces the risk of CHD. In 2004, the US Food and Drug Administration (FDA) determined that it would allow a qualified health claim stating that consuming 1.5 ounces of walnuts per day, as part of a diet low in saturated fat and cholesterol, may reduce the risk of CHD. The FDA has concluded that this claim is based on supporting, rather than conclusive, evidence.

Sources Ref 8478 Ref 13299 Ref 102335
Insufficient Reliable Evidence To Rate Diabetes
Rating & evidence shown verbatim from Natural Medicines

Data from preliminary clinical research on the effects of English walnuts in people with type 2 diabetes are conflicting. Some clinical research shows that taking English walnut leaf extract 100 mg twice daily for 3 months decreases fasting blood glucose by about 13% when compared with placebo. In contrast, other clinical research shows that taking English walnut leaf extract 100 mg once daily for one week and then twice daily for 7 weeks has no effect on fasting blood glucose levels. In a meta-analysis of 4 studies involving a total of 195 patients, taking English walnut leaf extracts orally, 200-750 mg daily for 8 to 12 weeks, reduces fasting blood glucose by a mean of about 18 mg/dL and increases fasting insulin levels by a mean of about 2 units/L, but does not alter post-prandial glucose levels. The majority of studies do not show a significant effect on glycated hemoglobin (HbA1c), but the meta-analysis shows a reduction when English walnut leaf extracts are taken for more than 8 weeks.

Sources Ref 97750 Ref 97749 Ref 113406

Source & disclaimer. Effectiveness ratings and evidence summaries are provided by Natural Medicines (Therapeutic Research Center) and shown as licensed. Where Natural Medicines hasn’t rated a use, HelloPharmacist’s pharmacists may add their own reviewed rating and evidence (each such entry is labeled). This is educational information, not medical advice — talk with your pharmacist or doctor before starting, stopping, or changing a supplement.

Safety & precautions

Walnuts eaten as food are generally safe for most people. The biggest concern is tree nut allergy, which can cause severe and even life-threatening reactions. Anyone with a known nut allergy should avoid walnuts and walnut-containing products.

Concentrated supplements made from walnut leaves or husks have not been well studied for safety. The husks and leaves contain juglone, which can be irritating in large amounts. People with kidney problems or those prone to oxalate kidney stones may want to be cautious, since walnuts contain oxalates.

For pregnancy and breastfeeding, eating walnuts as a normal part of the diet is generally considered fine. However, there is not enough information on concentrated walnut leaf or husk extracts, so these should be avoided to be safe. Always talk to your pharmacist or doctor before starting any supplement.

Side effects

For most people, eating walnuts causes few problems. Possible side effects include stomach upset or bloating, especially if eaten in large amounts because of the fat and fiber content.

The most serious risk is an allergic reaction in people sensitive to tree nuts. Symptoms can include itching, swelling, hives, trouble breathing, or anaphylaxis, which is a medical emergency. Walnut husks and concentrated leaf products may also cause skin or mouth irritation in some people.

English Walnut: Reported Adverse Effects

Documented safety reports on English Walnut from the evidence-graded Natural Medicines (TRC Healthcare) database, shown word-for-word from the licensed record.

Orally, the fruit (nut) of English walnut is well tolerated; however, it can cause softening of stools and mild bloating. Oral allergy syndrome may occur in people who are allergic to English walnuts. This is characterized by itching of the oral cavity immediately after consumption. Rarely this syndrome may cause swelling of the lips and tongue (angioedema). English walnut leaf extract has been reported to cause gastrointestinal adverse events, especially mild diarrhea. Daily use of English walnut bark is associated with increased risk of tongue cancer and lip leukoplakia due to its juglone content.

Topically, English walnut hull preparations can lead to yellow or brown discoloration of skin and mucous membranes due to its juglone content. It can also cause contact dermatitis.

  1. Chisholm A, Mann J, Skeaff M, et al. A diet rich in walnuts favourably influences plasma fatty acid profile in moderately hyperlipidaemic subjects. Eur J Clin Nutr 1998;52:12-6.
  2. Sabate J, Fraser GE, Burke K, et al. Effects of walnuts on serum lipid levels and blood pressure in normal men. N Engl J Med 1993;328:603-7.
  3. Zambon D, Sabate J, Munoz S, et al. Substituting walnuts for monounsaturated fat improves the serum lipid profile of hypercholesterolemic men and women. A randomized crossover trial. Ann Intern Med 2000;132:538-46.
  4. Asero R. Detection and clinical characterization of patients with oral allergy syndrome caused by stable allergens in Rosaceae and nuts. Ann Allergy Asthma Immunol 1999;83:377-83.
  5. Hosseini S, Jamshidi L, Mehrzadi S, et al. Effects of Juglans regia L. leaf extract on hyperglycemia and lipid profiles in type two diabetic patients: a randomized double-blind, placebo-controlled clinical trial. J Ethnopharmacol. 2014;152(3):451-6.
  6. Blumenthal M, ed. The Complete German Commission E Monographs: Therapeutic Guide to Herbal Medicines. Trans. S. Klein. Boston, MA: American Botanical Council, 1998.
  7. McGuffin M, Hobbs C, Upton R, Goldberg A, eds. American Herbal Products Association's Botanical Safety Handbook. Boca Raton, FL: CRC Press, LLC 1997.
  8. Bonamonte D, Foti C, Angelini G. Hyperpigmentation and contact dermatitis due to Juglans regia. Contact Dermatitis 2001;44:101-2.
Reports by condition
Allergic rhinitis (hay fever) Immunologic

Tree nuts, which include English walnuts, can cause allergic reactions in sensitive individuals. Due to the prevalence of this allergy in the general population, tree nuts are classified as a major food allergen in the United States.

Oral allergy syndrome may occur in people who are allergic to English walnuts. This is characterized by itching of the oral cavity immediately after consumption. Rarely this syndrome may cause swelling of the lips and tongue (angioedema).

  1. Food and Drug Administration. Food Allergen Labeling and Consumer Protection Act of 2004 (FALCPA); Public Law 108-282, Title II. Accessed on May 19, 2021. Available at: https://www.fda.gov/food/food-allergensgluten-free-guidance-documents-regulatory-infor
  2. Asero R. Detection and clinical characterization of patients with oral allergy syndrome caused by stable allergens in Rosaceae and nuts. Ann Allergy Asthma Immunol 1999;83:377-83.
Allergic rhinitis (hay fever) Gastrointestinal

Orally, the fruit (nut) of English walnut might cause softening of stools and mild bloating. Oral allergy syndrome may occur in people who are allergic to English walnuts. This is characterized by itching of the oral cavity immediately after consumption. Rarely this syndrome may cause swelling of the lips and tongue (angioedema). Walnut leaf extract has been reported to cause gastrointestinal adverse events, especially mild diarrhea, in 39% of adults in one study. Daily use of walnut bark is associated with increased risk of tongue cancer and lip leukoplakia due to its juglone content.

  1. Zambon D, Sabate J, Munoz S, et al. Substituting walnuts for monounsaturated fat improves the serum lipid profile of hypercholesterolemic men and women. A randomized crossover trial. Ann Intern Med 2000;132:538-46.
  2. Asero R. Detection and clinical characterization of patients with oral allergy syndrome caused by stable allergens in Rosaceae and nuts. Ann Allergy Asthma Immunol 1999;83:377-83.
  3. Hosseini S, Jamshidi L, Mehrzadi S, et al. Effects of Juglans regia L. leaf extract on hyperglycemia and lipid profiles in type two diabetic patients: a randomized double-blind, placebo-controlled clinical trial. J Ethnopharmacol. 2014;152(3):451-6.
  4. Blumenthal M, ed. The Complete German Commission E Monographs: Therapeutic Guide to Herbal Medicines. Trans. S. Klein. Boston, MA: American Botanical Council, 1998.
  5. McGuffin M, Hobbs C, Upton R, Goldberg A, eds. American Herbal Products Association's Botanical Safety Handbook. Boca Raton, FL: CRC Press, LLC 1997.
Dermatitis Dermatologic

Topically, English walnut hull preparations, which contain juglone, can cause a temporary yellow or brown discoloration of skin and mucous membranes. It can also cause contact dermatitis.

  1. McGuffin M, Hobbs C, Upton R, Goldberg A, eds. American Herbal Products Association's Botanical Safety Handbook. Boca Raton, FL: CRC Press, LLC 1997.
  2. Bonamonte D, Foti C, Angelini G. Hyperpigmentation and contact dermatitis due to Juglans regia. Contact Dermatitis 2001;44:101-2.
DISCLAIMER: This tool is intended for informational purposes only, and should not be interpreted as specific medical advice. Patients should consult with a qualified healthcare provider before making decisions about therapies and/or health conditions.

Adverse-effects data: Natural Medicines, Therapeutic Research Center

Dosing

There is no official standardized medicinal dose for English walnut. As a food, a small handful of walnuts is a common everyday serving and fits into most healthy diets.

For capsules, walnut oil, or leaf extracts, a proven therapeutic dose has not been established. The best advice is to follow the directions on the product label and to check with your pharmacist or doctor, especially if you take other medicines or have health conditions.

Pregnancy & Breastfeeding

English Walnut & Pregnancy

Likely Safe

When the fruit (nut), leaf, or hull is consumed in amounts normally found in foods.

  1. Electronic Code of Federal Regulations. Title 21. Part 182 -- Substances Generally Recognized As Safe. Available at: https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?CFRPart=182
Possibly Unsafe

When the bark is used orally or topically; avoid using. There is insufficient reliable information available about the safety of the fruit, leaf, or hull when used orally in medicinal amounts during pregnancy and lactation; avoid using.

  1. McGuffin M, Hobbs C, Upton R, Goldberg A, eds. American Herbal Products Association's Botanical Safety Handbook. Boca Raton, FL: CRC Press, LLC 1997.

English Walnut & Breastfeeding

Likely Safe

When the fruit (nut), leaf, or hull is consumed in amounts normally found in foods.

  1. Electronic Code of Federal Regulations. Title 21. Part 182 -- Substances Generally Recognized As Safe. Available at: https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?CFRPart=182
Possibly Unsafe

When the bark is used orally or topically; avoid using. There is insufficient reliable information available about the safety of the fruit, leaf, or hull when used orally in medicinal amounts during pregnancy and lactation; avoid using.

  1. McGuffin M, Hobbs C, Upton R, Goldberg A, eds. American Herbal Products Association's Botanical Safety Handbook. Boca Raton, FL: CRC Press, LLC 1997.
DISCLAIMER: This tool is intended for informational purposes only, and should not be interpreted as specific medical advice. Patients should consult with a qualified healthcare provider before making decisions about therapies and/or health conditions.

© 2026 Therapeutic Research Center

Pregnancy & lactation ratings: Natural Medicines, Therapeutic Research Center

References & further reading

The 16 references that drive our English Walnut monograph and interaction data, from the evidence-graded Natural Medicines (TRC Healthcare) database. Citations with a link open the study on PubMed or the publisher’s site.

  1. Blumenthal M, ed. The Complete German Commission E Monographs: Therapeutic Guide to Herbal Medicines. Trans. S. Klein. Boston, MA: American Botanical Council, 1998.
  2. McGuffin M, Hobbs C, Upton R, Goldberg A, eds. American Herbal Products Association's Botanical Safety Handbook. Boca Raton, FL: CRC Press, LLC 1997.
  3. Electronic Code of Federal Regulations. Title 21. Part 182 -- Substances Generally Recognized As Safe. Available at: https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?CFRPart=182
  4. Zambon D, Sabate J, Munoz S, et al. Substituting walnuts for monounsaturated fat improves the serum lipid profile of hypercholesterolemic men and women. A randomized crossover trial. Ann Intern Med 2000;132:538-46. PubMed
  5. Chisholm A, Mann J, Skeaff M, et al. A diet rich in walnuts favourably influences plasma fatty acid profile in moderately hyperlipidaemic subjects. Eur J Clin Nutr 1998;52:12-6. PubMed
  6. Sabate J, Fraser GE, Burke K, et al. Effects of walnuts on serum lipid levels and blood pressure in normal men. N Engl J Med 1993;328:603-7. PubMed
  7. Feldman EB. The scientific evidence for a beneficial health relationship between walnuts and coronary heart disease. J Nutr 2002;132:1062S-101S. PubMed
  8. Asero R. Detection and clinical characterization of patients with oral allergy syndrome caused by stable allergens in Rosaceae and nuts. Ann Allergy Asthma Immunol 1999;83:377-83. PubMed
  9. Bonamonte D, Foti C, Angelini G. Hyperpigmentation and contact dermatitis due to Juglans regia. Contact Dermatitis 2001;44:101-2. PubMed
  10. Hu FB, Stampfer MJ. Nut consumption and risk of coronary heart disease: a review of epidemiologic evidence. Curr Atheroscler Rep 1999;1:204-9. PubMed
  11. Tapsell LC, Gillen LJ, Patch CS, et al. Including walnuts in a low-fat/modified-fat diet improves HDL cholesterol-to-total cholesterol ratios in patients with type 2 diabetes. Diabetes Care 2004;27:2777-83. PubMed
  12. Rabiei K, Ebrahimzadeh MA, Saeedi M, et al. Effects of a hydroalcoholic extract of Juglans regia (walnut) leaves on blood glucose and major cardiovascular risk factors in type 2 diabetic patients: a double-blind, placebo-controlled clinical trial. BMC Com PubMed
  13. Hosseini S, Jamshidi L, Mehrzadi S, et al. Effects of Juglans regia L. leaf extract on hyperglycemia and lipid profiles in type two diabetic patients: a randomized double-blind, placebo-controlled clinical trial. J Ethnopharmacol. 2014;152(3):451-6. PubMed
  14. FDA. Qualified Health Claims: Letter of Enforcement Discretion - Walnuts and Coronary Heart Disease (Docket No 02P-0292). March 2004. Available at: http://wayback.archive-it.org/7993/20171114183649/https:/www.fda.gov/Food/IngredientsPackagingLabeling/Labe
  15. Food and Drug Administration. Food Allergen Labeling and Consumer Protection Act of 2004 (FALCPA); Public Law 108-282, Title II. Accessed on May 19, 2021. Available at: https://www.fda.gov/food/food-allergensgluten-free-guidance-documents-regulatory-infor
Keep reading

This information is for education only and is not a substitute for professional medical advice. Always check with your pharmacist or doctor before starting, stopping, or combining supplements and medications.

Parts of this content are provided by the Therapeutic Research Center, LLC.

DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.

© 2021 Therapeutic Research Center, LLC

Brand directory

Brands that make products with English Walnut

13 brands in our database make a supplement containing English Walnut.

Product directory

Supplement products with English Walnut

34 products in our database contain English Walnut. Open any to see its full ingredient list and every drug interaction we check.

Pharmacist Counseling Corner

English Walnut: Common Questions

What is English Walnut used for, and does it work?
People use English Walnut for many reasons, but the evidence varies by use. According to the Natural Medicines database, there is at least some clinical evidence supporting English Walnut for Hypercholesterolemia. For most other uses it has been studied for, the evidence is currently insufficient to rate. See the graded list on this page, and always confirm with your pharmacist or doctor.
Does English Walnut interact with prescription medications?
We do not currently list any known drug interactions for English Walnut. This does not guarantee that none exist, so always confirm with your pharmacist before combining it with your medications.
How are English Walnut interactions rated?
Each interaction is graded major, moderate, or minor based on how clinically significant it is and the strength of the evidence behind it. Major interactions are the most serious and are best avoided, or used only under close professional supervision.
Is it safe to take English Walnut with my medications?
It depends on the specific medication. Some combinations are fine, while others call for monitoring, timing changes, or should be avoided. Check your exact drug above and confirm with your pharmacist or doctor before starting, stopping, or changing anything.
Where does this English Walnut interaction information come from?
Our interaction data is built on the Natural Medicines database — an evidence-graded reference for vitamins, herbs, and supplements — and is reviewed by licensed HelloPharmacist pharmacists, who may add clinical context.
Are English Walnuts good for your heart?
Eating walnuts as part of a balanced diet may help support healthy cholesterol levels and heart health, largely because of their plant-based omega-3 fats and fiber. They are not a cure or a replacement for prescribed heart treatments.
Can I be allergic to English Walnuts?
Yes. Walnuts are tree nuts and can cause serious allergic reactions, including anaphylaxis. If you have a known tree nut allergy, you should avoid walnuts entirely.
Is it safe to eat walnuts during pregnancy?
Eating walnuts as a normal food is generally considered safe during pregnancy unless you have a nut allergy. Concentrated walnut leaf or husk supplements have not been studied, so it is best to avoid them while pregnant or breastfeeding.
How many walnuts should I eat a day?
A small handful is a common daily serving that fits into a healthy diet. Because walnuts are high in calories and fat, it is best to enjoy them in moderation rather than large amounts.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

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