Is Bilberry Good for Diarrhea? Traditional Use and Modern Evidence

November 26, 2025 •

4 min read

For centuries, European folk medicine has relied on dried bilberry fruit to address mild diarrhea and other gastrointestinal complaints. These tiny, dark berries contain compounds that are traditionally believed to have astringent and anti-inflammatory effects, leading many to question: is bilberry good for diarrhea based on modern evidence?

Quick Summary

The dried fruit of the bilberry contains tannins, which are thought to alleviate mild diarrhea by reducing intestinal inflammation and fluid secretion. Evidence is largely traditional, but some studies point to potential benefits for gut health.

Key Points

Dried bilberry is key: The antidiarrheal effects are attributed to dried fruit, not fresh, which can have a laxative effect.
Tannins are the active compound: The astringent properties of tannins in dried bilberry may help reduce intestinal inflammation and fluid secretion.
Evidence is largely traditional: Centuries of use in European folk medicine support bilberry's role for mild diarrhea, though modern clinical trials are limited.
Consult a healthcare provider: Due to potential interactions with medications, especially blood thinners and diabetes drugs, medical advice is essential.
Not for long-term use: If diarrhea persists beyond 3-4 days, it is important to seek medical attention, as it may indicate a more serious issue.
Bilberry leaves can be toxic: The leaves should not be consumed in high or prolonged doses, as they can cause serious side effects.

Traditional Wisdom on Bilberry for Diarrhea

For hundreds of years, bilberry (specifically the dried fruit of Vaccinium myrtillus) has been a staple in European herbal medicine for treating acute, non-specific diarrhea. This practice is built on the understanding of the berries' natural compounds, particularly tannins. Tannins are polyphenolic compounds with astringent properties, meaning they can contract or tighten body tissues, which was believed to help reduce inflammation in the gastrointestinal tract and decrease the amount of fluid secreted into the intestines. The key distinction, as emphasized in traditional texts, is that only the dried fruit possesses this effect; fresh bilberries are often cited as having a mild laxative effect, likely due to their pectin content and overall high moisture.

The Science Behind Bilberry's Potential

While the bulk of bilberry's antidiarrheal reputation is historical and anecdotal, some modern research has begun to explore its mechanisms. Scientific studies point to the potential role of bilberry's compounds, including tannins and anthocyanins, in supporting gut health. Anthocyanins, the pigments that give bilberries their dark color, are potent antioxidants and anti-inflammatory agents. Animal studies have shown that bilberry extracts can ameliorate experimentally induced colitis, reducing disease severity and inflammation in the gut. This suggests that the anti-inflammatory effects of bilberry's components could play a role in calming an irritated or inflamed digestive tract. However, experts note that rigorous clinical trials to validate bilberry's efficacy specifically for diarrhea in humans are still limited.

How to Use Bilberry for Mild Diarrhea

If you choose to use bilberry for mild, short-term diarrhea, the traditional method involves using the dried fruit. It is crucial to note the difference between fresh and dried berries to avoid a counterproductive effect. Consult a healthcare provider before starting any new herbal supplement, especially if you take other medications or have underlying health conditions.

Here are some common preparation methods:

Bilberry Tea: Boil one tablespoon of crushed dried bilberries in water for about ten minutes, then strain and drink.
Chewed Dried Berries: Chew and swallow whole dried bilberries, typically around three tablespoons per day.
Extracts and Capsules: Standardized extracts are also available. Dosage can vary, so follow the product's instructions or a healthcare professional's advice.

Regardless of the form, bilberry tea should not be used as an herbal medicine for more than three or four days. If diarrhea persists, you should seek medical attention.

Important Considerations and Safety

While bilberry fruit and its extracts are generally considered safe for most people when consumed in typical food amounts or for short-term use, there are important safety considerations.

Medication Interactions: Bilberry fruit can interact with certain medications. For instance, it can increase the effects of blood-thinning medications like aspirin, raising the risk of bleeding. It can also lower blood sugar levels, which is a concern for individuals with diabetes.
Leaf vs. Fruit: Bilberry leaves should not be consumed in high doses or for extended periods due to potential toxicity. The fruit is the primary part used for diarrhea treatment.
Underlying Conditions: Diarrhea can be a symptom of a more serious medical condition. It is important to consult a doctor if diarrhea is severe, persistent, or accompanied by other symptoms.

Comparison: Bilberry vs. Other Traditional Remedies


Feature	Bilberry (Dried Fruit)	Blackberry (Leaves/Root Bark)	Red Raspberry (Leaves)
Primary Mechanism	Tannins provide astringent effect, reducing fluid secretion.	High tannin content provides astringent action.	Also high in tannins, acting as an astringent.
Key Benefit	Primarily known for its antidiarrheal properties.	Known for relieving acute diarrhea.	Can help relieve acute diarrhea.
Form Used	Dried fruit is most effective; fresh fruit is not.	Leaves and root bark are traditionally used.	Leaves are primarily used.
Traditional Origin	European herbal medicine.	Widely used in traditional herbal medicine.	Traditional herbal remedy.
Effectiveness	Traditional use is strong, but modern clinical evidence is limited.	Relies heavily on traditional and anecdotal evidence.	Primarily based on traditional use.
Fresh vs. Dried	Fresh may have laxative effect; dried has antidiarrheal.	Fresh fruit does not have the same astringent effect.	Not typically used fresh for this purpose.

Conclusion: The Role of Bilberry in Diarrhea Management

While a long history of traditional use supports the idea that is bilberry good for diarrhea, it's crucial to approach this herbal remedy with a balanced perspective. The evidence, primarily based on anecdotal accounts and preliminary research into its compounds like tannins and anthocyanins, suggests it may help alleviate mild, short-term diarrhea. The astringent action of dried bilberry fruit is the core of its therapeutic potential, helping to calm an inflamed gut and reduce fluid output. However, robust modern clinical trials are lacking, and it is important to distinguish between the dried fruit and fresh berries, which can have an opposite effect. For persistent or severe diarrhea, or if you are taking other medications, always consult a healthcare professional. For more information on complementary and integrative health, visit the National Center for Complementary and Integrative Health.

Frequently Asked Questions

No, it is important to use dried bilberry fruit for its antidiarrheal effects. Fresh bilberries contain pectin and can have a mild laxative effect.

Bilberry contains tannins, which have astringent properties. These tannins can reduce inflammation in the gastrointestinal tract and decrease fluid secretion, helping to firm up stools.

It is not recommended to use bilberry leaves, especially in high or prolonged doses, as they can cause toxic side effects. The dried fruit is the part traditionally used for diarrhea.

Bilberry can interact with certain medications, including blood-thinners and diabetes drugs. You should consult a healthcare provider before using bilberry if you are taking any other medications.

The most common preparations are a tea made from boiled, crushed dried bilberries or by chewing and swallowing the dried berries whole.

Bilberry tea or supplements for diarrhea should not be used for more than three or four days. If symptoms persist beyond this time, it is important to see a doctor.

While anecdotal and traditional evidence is strong, modern clinical evidence is limited. Some animal and lab studies suggest potential anti-inflammatory benefits, but robust human trials are lacking.