What are the side effects of mulberries?

November 4, 2025 •

3 min read

While celebrated for their sweet flavor and nutritional value, mulberries can cause adverse effects if not consumed with caution. Rich in antioxidants, vitamins, and minerals, these berries offer several health benefits, but understanding the potential side effects of mulberries is crucial for avoiding complications, especially for those with pre-existing health conditions or taking specific medications.

Quick Summary

This guide details the various health risks associated with mulberries, including their impact on blood sugar levels, potential digestive upset, allergic reactions, and interactions with common medications. It outlines who should be cautious when consuming mulberries and provides guidance on safe consumption.

Key Points

Hypoglycemia Risk: Mulberries, especially extracts, can significantly lower blood sugar, posing a risk for individuals with diabetes or those on antidiabetic medication.
Digestive Distress: Overconsuming mulberries can cause bloating, gas, diarrhea, or nausea due to their high fiber content.
Allergic Reactions: Though rare, mulberries can trigger allergic responses, particularly in those with sensitivities to birch pollen or other Moraceae family fruits.
Medication Interference: Mulberries can interact with drugs for diabetes, cholesterol, and blood thinners, potentially causing dangerous fluctuations in their effects.
High Potassium Levels: Individuals with kidney problems should limit their mulberry intake due to the fruit's high potassium content, which can strain kidney function.
Moderation is Key: To avoid potential side effects, mulberries should be consumed in moderation as part of a balanced diet.
Toxicity of Unripe Fruit: The consumption of unripe mulberries and specific parts of the mulberry tree can be toxic.

Mulberries, derived from the Morus tree, are consumed worldwide for their delicious taste and health-promoting compounds. However, their bioactive properties can sometimes lead to unexpected and undesirable side effects, particularly with excessive consumption or in sensitive individuals. This article explores the potential health risks associated with mulberries.

Hypoglycemia and Blood Sugar Regulation

One of the most significant concerns for certain individuals is mulberry's impact on blood sugar levels. The fruit and, more notably, extracts from the mulberry leaf, contain a compound called 1-deoxynojirimycin (DNJ), which inhibits enzymes that break down carbohydrates into glucose. This action can lead to a considerable drop in blood glucose levels, particularly in individuals with type 2 diabetes.

Symptoms of hypoglycemia, or low blood sugar, include:

Dizziness
Sweating
Blurry vision
Tremors
Weakness

Patients on diabetes medication, such as insulin or oral antidiabetic drugs, must exercise caution and consult a healthcare provider before incorporating mulberries or their supplements into their diet. The combined effect could cause dangerously low blood sugar levels.

Digestive Issues

Overconsumption of mulberries can lead to gastrointestinal discomfort due to their high fiber content. While dietary fiber generally aids digestion, a sudden increase in intake can trigger adverse reactions in sensitive individuals.

Common digestive side effects include:

Diarrhea
Bloating
Gas
Nausea and indigestion
Constipation, paradoxically, can also occur with excessive intake, despite the high fiber

Comparing Digestive Effects of Fresh vs. Dried Mulberries


Aspect	Fresh Mulberries	Dried Mulberries
Fiber Concentration	High water content dilutes fiber content.	Higher fiber concentration by weight.
Digestive Impact	Less likely to cause significant issues unless consumed in large quantities.	More potent effects on digestion due to concentrated fiber. Overconsumption can easily lead to bloating and gas.
Portion Control	Easier to moderate intake due to natural water content.	Requires more careful portion control as they are smaller and more calorie-dense.

Allergic Reactions

Though relatively rare, allergic reactions to mulberries can occur, especially in individuals with a known sensitivity to other members of the Moraceae family, such as figs or breadfruit. Cross-reactivity with birch pollen is also possible, leading to Oral Allergy Syndrome (OAS).

Allergy symptoms can range from mild to severe and include:

Itching or swelling of the mouth, lips, and throat
Skin rashes or hives
Breathing difficulties or wheezing in severe cases
Anaphylaxis, though uncommon, has been reported

Medication Interactions

Mulberries can interact with several types of medication, potentially altering their effectiveness or amplifying side effects.

Diabetes Medications: As mentioned, mulberries can lower blood sugar, and combining them with insulin or oral antidiabetic drugs may cause hypoglycemia.
Blood Thinners (Anticoagulants): Mulberries may enhance the effect of blood-thinning medications like warfarin, increasing the risk of bleeding.
Cholesterol Medications: White mulberry in particular might lower cholesterol, which can increase the effects of cholesterol-lowering drugs like atorvastatin (Lipitor).
Immunosuppressants: Mulberry has been shown to interact with the immunosuppressant cyclosporine, decreasing its bioavailability.

Kidney Concerns

Mulberries contain high levels of potassium, a mineral vital for body function. However, individuals with kidney disease need to monitor their potassium intake carefully. Excessive potassium can be problematic for those with impaired kidney function, potentially straining the kidneys and causing issues.

Conclusion

While mulberries are a nutritious fruit with many health benefits, it is important to be mindful of their potential side effects. These risks are generally associated with excessive intake, specific pre-existing health conditions like diabetes or kidney disease, and interactions with certain medications. Moderate consumption as part of a balanced diet is generally considered safe for most people, but anyone with underlying medical issues or concerns about drug interactions should consult a healthcare professional. Unripe mulberries and other parts of the plant, such as the wood of the white mulberry tree, can contain toxic compounds and should be avoided. By understanding these potential downsides, you can safely enjoy the benefits of this flavorful fruit.

Visit the NIH website for more detailed research on mulberry and drug interactions.

Frequently Asked Questions

Yes, mulberries, particularly the leaf extract, contain compounds that can lower blood sugar levels. This is a risk for individuals with diabetes or those taking medication to regulate blood glucose.

Yes, excessive consumption of mulberries can lead to digestive discomfort, including bloating, gas, diarrhea, or nausea, due to their high fiber content.

People with diabetes on medication, individuals with kidney disease due to the high potassium content, pregnant and breastfeeding women due to insufficient safety research, and those with known allergies to mulberries or related plants should avoid or limit intake.

Yes, mulberries can interact with medications for diabetes, blood thinners, and cholesterol. Consult a healthcare provider if you are on any medication before consuming mulberries or their supplements.

Yes, allergic reactions to mulberries have been reported, although they are uncommon. People allergic to birch pollen or figs may also experience cross-reactivity.

A recommended intake of around 40 grams of mulberries per day is often cited for healthy individuals. However, this can vary, and portion control is vital to avoid digestive issues.

Yes, the unripe fruit and the wood of the white mulberry tree can contain toxic compounds and should be avoided. Only ripe mulberries should be consumed.