Progesterone injection

Injectable progesterone, often in an oil base, is given into a large muscle such as the buttock and gives reliable blood levels. Injections can cause soreness or lumps at the site, so clinics advise rotating sides and using warmth afterwards. Some protocols combine injections with vaginal progesterone.

Also known as: intramuscular progesterone, PIO, progesterone in oil

Last reviewed: 8 September 2026. Written by the Antega Editorial Team. General information only — always follow the advice of your own clinic, doctor or pharmacist.