Licorice intoxication or overdose is possible and has been associated with death and rhabdomyolysis (muscle breakdown due to low potassium) in case studies.[1][2][3] In one small study, 3 of 4 people who consumed 200 grams of licorice in under an hour reported feelings of nausea and fatigue which correlated with serum glycyrrhizin levels.[1]
The glycyrrhizin component of licorice in particular may raise blood pressure in individuals with hypertension.[4][5][6] However, supplements with reduced (or undetectable) glycyrrhizin content may not be associated with the same adverse effects.[7]
High doses of licorice (>500 mg of glycyrrhizin) are known to increase cortisol levels, decrease testosterone, and alter estrogen receptor activity.[8][9][10][11][12][13][14][15][16][17][18][19] Some of the hormonal effects of licorice (including increases in parathyroid hormone and decreases in DHEA) may be sex dependent.[20][21] Though licorice shows some promise for body fat reduction, these results are still conflicting, and it is possible that weight can increase through water retention.[22][4][23][24]