Licorice products that include glycyrrhizin may increase blood pressure and cause water retention and potassium deficiency.¹⁰ Some people are more sensitive to this effect than others. Long-term intake (more than two to three weeks) of products containing more than 1 gram of glycyrrhizin (the amount in approximately 10 grams of root) daily is the usual amount required to cause these effects. Consumption of 7 grams licorice (containing 500 mg glycyrrhizin) per day for seven days has been shown to decrease serum testosterone levels in healthy men by blocking the enzymes needed to synthesize testosterone.¹¹ However, in another study, a similar amount of licorice had only a small and statistically insignificant effect on testosterone levels.¹² As a result of these possible side effects, long-term intake of high levels of glycyrrhizin is discouraged and should only be undertaken if prescribed by a qualified healthcare professional. Consumption of plenty of fresh fruits and vegetables to increase potassium intake is recommended to help decrease the chance of potassium deficiency. According to the German Commission E monograph, licorice is inadvisable for pregnant women as well as for people with liver and kidney disorders.¹³

De-glycyrrhizinated licorice extracts usually do not cause these side effects since 97% of the glycyrrhizin has been removed.