These effects can be especially dangerous if you take digitalis, or if you have high blood pressure, heart disease, diabetes, or kidney disease. Licorice may also reduce testosterone levels in men. For this reason, men with impotence, infertility, or decreased libido may wish to avoid this herb. Licorice may also increase both the positive and negative effects of treatment with corticosteroids, such as prednisone. 10 DGL is believed to be safe, although extensive safety studies have not been performed.
Side effects are rare.
Safety for either form of licorice in young children, pregnant or nursing women, or those with severe liver or kidney disease has not been established. According to one report, licorice possesses significant estrogenic activity and, as such, shouldn't be taken by women who have had breast cancer. Newall C, et al. A guide for health-care professionals. Johnson B and McIssac R. Effect of some anti-ulcer agents on mucosal blood flow.