The effects of the aqueous extract of the leaf of Euphrasia officinale on blood glucose levels in normal and alloxan-diabetic rats were investigated. The treatment of alloxan-induced diabetic rats brought down the raised glucose levels, while the extract was devoid of hypoglycemic effect in normal rats.
– Fitoterapia 2000 Sep;71(5):522-6 — Antihyperglycemic activity of Euphrasia officinale leaves. — Porchezhian E, Ansari SH, Shreedharan NK.

Not recommended for eyes due to the danger of eye infections.
– Newall CA, Anderson LA, Phillipson JD: Herbal Medicines. — A Guide for Health-care Professionals. Pharmaceutical Press, London, 1996.

Safety during pregnancy and lactation has not been proven.

May cause skin reactions in some individuals. Other possible side effects are possible.