Alder Buckthorn

The Alder Buckthorn, botanically Rhamnus frangula, also called Gemeiner Faulbaum or Schwarzdorn, belongs to the buckthorn family (Rhamnaceae). It is a deciduous shrub or small tree that is widespread in Europe, North Africa, and parts of Asia. Typical features are its smooth, gray-brown bark, which smells unpleasant when scratched – hence the German name Faulbaum –, as well as the simple, glossy green leaves. In early summer, the plant bears inconspicuous greenish-white flowers, from which black-violet stone fruits develop.

Ecologically, the Alder Buckthorn plays an important role, as it serves as food for numerous insects, including butterfly caterpillars. At the same time, it has been valued in folk medicine for centuries, especially for its bark.

What health benefits does the Alder Buckthorn offer?

In naturopathy, it is primarily the dried bark that is of importance, which is known as a mild herbal laxative. The effects are mainly based on the anthranoids it contains. Beyond this, however, studies have also revealed further potentially positive effects of the plant. Even though more research is needed to draw definitive conclusions, here are some of the findings from research so far:

  • Antimicrobial and antiviral effect: The bark of the Alder Buckthorn contains compounds that show an antimicrobial and antiviral effect in scientific studies (1).
  • Digestive support: Alder Buckthorn bark is traditionally used for occasional constipation. Rhamnus frangula contains anthraquinone glycosides, which are activated in the large intestine, where they stimulate peristalsis (muscle contractions) and draw water and electrolytes into the intestinal lumen. As a result, they make the stool softer and promote bowel activity (1,2).
  • Anticarcinogenic effect: Studies suggest that extracts from Rhamnus frangula (especially the FA and E fractions) exhibit a cytotoxic effect on carcinoma cells and could trigger apoptosis there (3).

How does the Alder Buckthorn work in the body?

The laxative effect of the bark is based on anthranoids (especially frangulins and glucofrangulins). These compounds are broken down by bacteria in the large intestine and stimulate intestinal peristalsis. In addition, they increase the water content of the stool, which facilitates bowel movements. The Alder Buckthorn and its main active compound emodin show a marked anticancer activity by reducing the cell viability of cancer cells, triggering cell cycle arrest, promoting apoptosis, and causing genotoxic effects. Here too, further research is needed to fully understand the effect in all respects.

Are there any risks or side effects?

  • Do not use fresh: Fresh bark has a strong laxative effect and can cause vomiting. It must be stored for at least one year or treated by heating before it may be used medicinally.
  • Short-term use only: Longer-term intake is not recommended.
  • Not during pregnancy and breastfeeding: Caution is advised here.
  • Side effects: In rare cases, abdominal cramps may occur.
  • Only under medical supervision: Use should only take place under medical supervision

Conclusion

The Alder Buckthorn (Rhamnus frangula) is an inconspicuous but tradition-rich shrub that is both ecologically and medicinally significant. While it provides habitat and a food source for many animals, its bark holds a firm place in European phytotherapy as a mild laxative. However, proper use always remains important, as fresh or incorrectly prepared bark can produce unwanted effects. Furthermore, more studies must be conducted to understand the effect of the plant in its entirety. Until then, use should take place only under medical supervision.

Sources:

  1. Tebrencu, E., Cretu, R., Mitroi, G., Iacob, E., & Ionescu, E. (2015). Phytochemical evaluation and HPTLC investigation of bark and extracts of Rhamnus frangula Linn. Phytochemistry Reviews, 14, 10.1007/s11101-015-9410-8.
  2. European Medicines Agency (EMA). (n.d.). Frangulae cortex. European Medicines Agency. Retrieved August 19, 2025, from https://www.ema.europa.eu/en/medicines/herbal/frangulae-cortex
  3. Vuletić, S., Bekić, M., Tomić, S., Nikolić, B., Cvetković, S., Ganić, T., & Mitić-Ćulafić, D. (2023). Could alder buckthorn (