One dated study in 21 people found that taking 25 mg of guggulsterone orally was as effective as tetracycline, an antibiotic commonly used to treat acne.
Additionally, people with notably oily skin responded significantly better to guggulsterone than the tetracycline treatment.
Thappa, D., & Dogra, J. (1994). Nodulocystic Acne: Oral Gugulipid versus Tetracycline. The Journal of Dermatology, 21. https://doi.org/10.1111/j.1346-8138.1994.tb03277.x.
Another older study found that taking guggul orally for 6 weeks helped treat acne without causing any major adverse effects
Dogra, J., Aneja, N., & Saxena, V. (1990). Oral gugulipid in acne vulgaris management. Indian Journal of Dermatology, Venereology and Leprology, 56, 381-383.
