Guggul does not increase estrogen, but it possesses strong agonistic activity against estrogen receptor, which means, it mimics estrogen molecules and exhibits effects similar to estrogen. Guggulsterone, the key active constituent of guggul, activates estrogen receptor alpha isoform. [41] Higher estrogen levels are said to cause various health problems like irregular menstrual cycle, uterine fibroids, endometriosis, tumor growth in breasts, etc. [42][43] Therefore, individuals with higher estrogen levels in the body should avoid using guggul supplements. Healthy individuals should also be careful with dosage and must not consume more than what is recommended.