Educational Content: This article is for informational purposes only and does not constitute medical advice. Always consult a healthcare provider for diagnosis and treatment.
Definition of THG
Medically reviewed by Dr. Otari Nergadze, Neurosurgeon | Updated: January 2026
THG: Tetrahydrogestrinone. A "designer steroid." THG first surfaced in October 2003 with reports of its illicit use by athletes. A very potent androgenic steroid, with side effects such as hirsutism, acne and infertility. Considered a controlled substance in the United States. (CIII)