Borage is a diuretic, demulcent, diaphoretic and a aperient. The leaves and seeds of the plant are reputed to promote milk production in nursing mothers, and poultices of the leaves are often used to treat irregularities of the skin. An infusion of borage applied topically is an effective astringent due to the presence of tannin. The tannin content is also responsible for the mild constipating action produced when taken as a tea.
The mucilage found in borage gives it a mild expectorant action, and has been prescribed for many years to ease bronchial infections. In many parts of England today, borage is still referred to as “cool-tankard”, since the most popular method of administering borage was to partake of wine in which the leaves and flowers had been steeped, particularly if a dose of courage was the desired result.