Vaginal SYSTEMIC estrogen vs vaginal LOCAL estrogen ~ what's the difference?
There are two types of estrogen therapy, local estrogen therapy and systemic estrogen therapy.
Local vaginal estrogen therapy
Local vaginal estrogen therapy is low-dose and is primarily used to target the vaginal/vulvar tissue. The vagina and vulva are loaded with estrogen receptors, and a loss of estrogen can significantly impact the health of that tissue.
Providers will prescribe a local treatment meant to stay in the vaginal/vulvar tissues that will not circulate systemically to the rest of the body.
We often refer to this as “low dose” estrogen therapy because if we were to measure levels of estrogen in the blood, this type of therapy would not significantly raise blood levels (meaning it does not reach the other tissues in the body)
Low-dose vaginal estrogen is safe even for women with active breast cancer and women with a previous history of breast cancer. It can be started any time, in any woman, even in older women.
FDA approved formulations include Estrace (Estradiol 0.01% in a cream), Imvexxy (suppository), Vagifem (vaginal tablet), Estring (there may be a small amount of systemic absorption with this one).
Vaginal estradiol and vaginal estriol can be compounded by a compounding pharmacy—an option many women prefer because it allows for customized dosing and can be made with cleaner, simpler ingredients.
Systemically delivered vaginal estrogen
The vagina is very absorptive, so applying/inserting SYSTEMIC doses of estrogen to the vagina/vulva/intralabially will get picked up by the blood, and carry the estrogen systemically to the tissues throughout the body
For many women who do not absorb estrogen through the skin, vaginal delivery of systemic estrogen can be a great option.
It will also help to support the health of the vagina/vulva.
Because systemic estrogen is often well absorbed through the vagina, many women require a lower dosage than what was previously applied to the skin
The base of the prescription matters. Many of the FDA-approved vaginal estrogen formulations contain parabens, phthalates and other additives, which can cause irritation and other issues, so it is important to ensure that the base of your prescription is vagina friendly.
I highly recommend that if you are not interested in using systemic HRT, you consider a local vaginal estrogen (and consider local testosterone as there are loads of androgen receptors in the vulva).
Nearly every woman, if not all women, will ultimately experience significant changes in their vaginal/vulvar tissue that, over time, can lead to sexual symptoms, dryness, pain, recurring UTIs, incontinence, dryness, vaginal and vulvar atrophy, labial minor resorption (the labia minora atrophies so much that it disappears). These changes often don’t show up until a woman is in her 60s or 70s at which point it can be more difficult to repair the tissue and reverse tissue changes.
I hope this helps to clarify the difference between the two.