Alnus incana

Alnus incana works primarily through its high tannin content, which provides strong astringent properties. When applied to wounds, these tannins precipitate proteins to create a protective layer over the tissue, which helps reduce bleeding, secretion, and inflammation. This action promotes faster tissue repair and provides a barrier against infection. While these mechanisms are well-understood pharmacologically, specific clinical trials confirming efficacy are limited (Evidence Level C).

Due to its significant tannin content, Alnus incana may interfere with the absorption of certain oral medications if taken simultaneously. Tannins can bind to alkaloids and iron, potentially reducing their bioavailability and therapeutic effect. To avoid this interaction, it is advisable to separate the ingestion of alder bark preparations from prescription medications by at least two to three hours. Specific interaction studies are lacking (Evidence Level D).

The standard adult dosage for Alnus incana is approximately 2 grams of dried bark per day, typically prepared as a tea or decoction. To prepare, the bark is simmered in water to extract the active tannins and flavonoids. This dosage is based on traditional use and expert consensus rather than standardized clinical trials (Evidence Level C). Users should adhere to recommended amounts to avoid potential side effects like constipation.

Alnus incana is considered unsafe during pregnancy and should be avoided. The herb's strong astringent properties and potential effects on uterine tone pose risks during gestation. Additionally, the presence of active compounds like sesquiterpenes may present theoretical risks to fetal development. Safety data is limited, but traditional usage guidelines and regulatory classifications contraindicate its use for pregnant women (Evidence Level D).

The most commonly reported side effect of Alnus incana is constipation, which occurs due to the herb's high tannin content and astringent action on the digestive tract. Excessive consumption or prolonged use can exacerbate this effect. While generally considered safe at recommended doses for short-term use, individuals should discontinue use if gastrointestinal discomfort occurs. Long-term safety data is lacking (Evidence Level C).