Progesterone
Progesterone is a female sex hormone, responsible for managing parts of the menstrual cycle. In feminizing gender-affirming hormone therapy, it has been claimed to help with breast size, sexual desire, and mood, but there is a lack of scientific evidence for these claims. Oral progesterone also has bioavailability problems, and in order to derive any possible benefit from progesterone, you need to take it rectally (it is an oral medication but it's fine to take rectally). Common regimens are 100mg daily; 200 mg two weeks on/two weeks off; or one week on, three weeks off. Progesterone should not be started until Tanner 3 while on GAHT due to the fact that taking it too early can inhibit breast development.
Medical establishment
The mainstream medical establishment does not recommend progesterone, citing lack of evidence and unknown risks (the usual escuses)[2]. However, many medical systems do prescribe prog anyways, going against the guidelines.
References
- Aly. “Oral Progesterone Achieves Very Low Levels of Progesterone and Has Only Weak Progestogenic Effects.” Transfeminine Science, 4 Aug. 2018, transfemscience.org/articles/oral-p4-low-levels/. Accessed 1 Feb. 2026.
- Coleman, E., et al. “Standards of Care for the Health of Transgender and Gender Diverse People, Version 8.” International Journal of Transgender Health, vol. 23, no. S1, 19 Aug. 2022, pp. S1–S259, https://doi.org/10.1080/26895269.2022.2100644.