Understanding Progesterone in Hormone Therapy
I want to offer some clarity about progesterone and why it’s used in hormone therapy.
Why do you take progesterone in hormone therapy?
When using hormone therapy, if you have a uterus, progestogens are prescribed alongside estrogen to protect the uterus. Estrogen alone (called unopposed estrogen) has been clearly shown over decades to increase the risk of uterine cancer or precancer through overgrowth of the uterine lining.
This risk drops significantly—and returns to the baseline risk of an untreated woman—when the correct dose of progesterone is added. So, if you have a uterus and are taking estrogen, you should also be taking progesterone or a similarly acting agent. Please speak with your health care provider about your options. It’s important to understand that this combination is a necessary pairing (Menopause Society).
What About Compounded Hormones and Progesterone Cream?
I often see people using compounded topical (usually cream-based) progesterone, often alongside estrogen.
Why do I raise this point?
Unfortunately, topical progesterone creams do not offer adequate uterine protection. Even in the few small and short-term trials conducted, the results showed that these preparations did not deliver enough progesterone to protect the uterus.
If you’re seeking a hormone similar to what your body naturally produces, it’s important to know there are prescribed, regulated options that meet that standard. One of these is micronized progesterone (Prometrium), which is structurally identical to the progesterone made by your reproductive system. This medication is taken orally and may also offer additional benefits, such as improved sleep for some women. Please speak to your health care provider about the most appropriate prescription for you.
Also, note that compounded hormone formulations often include a mix of hormones, sometimes in untested or unproven combinations and with additional ingredients that are not evidence-based. Please use caution with these products and consider regulated, evidence-based options.
Bioidentical Hormones: What Does That Really Mean?
The desire to use hormones that resemble those naturally produced by the body often leads to confusion about what “bioidentical” means.
There are government-approved bioidentical hormones, such as the aforementioned micronized progesterone. However, not all products labeled as “bioidentical” are created equal. Some compounded products claim to be bioidentical, but are not regulated or tested to the same standard.
I encourage you to talk with your health care team about your treatment goals and values. If you’re starting or currently using hormone therapy, ensure your regimen aligns with both your preferences and the best available evidence.