Borage seed oil contains the omega-6 fatty acid known as gamma-linolenic acid. GLA is also produced naturally in the body and thought to have anti-inflammatory activity. Borage also contains mucilage, a sticky mixture of plant sugars that can act as an expectorant to produce phlegm in patients with coughs. Borage has been promoted for rheumatoid arthritis, skin inflammation, diabetic nerve pain, menopausal symptoms, and gastrointestinal issues, but research shows only moderate support for its use to relieve rheumatoid arthritis symptoms.
Although it has been suggested as an alternative source of GLA to evening primrose oil, borage seed oil can have toxic effects on the liver. Its chronic use should be avoided, especially by patients with liver disease or women who are pregnant or breastfeeding.