Estriol
Estriol (E3) is a weak estrogen used in Europe for menopausal vaginal atrophy. Not FDA-approved in the US; available only from compounding pharmacies.
How it works
Estriol is produced in large amounts during pregnancy and is the predominant estrogen in the postmenopausal period from peripheral conversion. It has weaker estrogen receptor affinity than estradiol and estriol — which contributes to its historically favorable safety profile in European practice for local vaginal use. In the US, estriol is not FDA-approved and is available only as a compounded product, meaning its potency and purity are not regulated by FDA standards the way that Vagifem or Imvexxy are. The European evidence base for vaginal estriol is substantial; comparable FDA-approved products in the US (ultra-low-dose estradiol tablets or inserts) are often preferred when regulatory oversight matters.
Vaginal estriol treats genitourinary syndrome of menopause: vaginal dryness, thinning, dyspareunia, and related urinary symptoms. Because it is weaker than estradiol, some individuals require more frequent application to maintain tissue effect. Systemic absorption from vaginal estriol is low, similar to other local vaginal estrogen products.
How to track Estriol
- Vaginal dryness and discomfort level — the primary symptom target; rate consistently from the start.
- Dyspareunia (painful intercourse) if applicable — track separately from general dryness.
- Application schedule and consistency — estriol may require more frequent application than estradiol products to maintain the same tissue effect.
- Urinary urgency, frequency, and UTI episodes — vaginal estriol has documented benefits on urinary symptoms.
- Compounding pharmacy details: formulation, lot numbers, and any changes in product — with compounded medications, batch variability is a real consideration worth documenting.
- Track symptoms from day one to establish a baseline — estriol's weaker receptor affinity means the tissue response curve may be slower than with estradiol products, and a log makes that trajectory visible.
- Note your compounding pharmacy, formulation, and any changes in the product — with unregulated compounded medications, batch-to-batch variability can affect symptom control.
- Log application frequency and any missed applications — estriol's weaker potency means adherence is particularly important.
- Rate urinary symptoms separately from vaginal symptoms — both may respond, but often on different timelines.
- If you are using estriol because you cannot use estradiol, document that clinical rationale in your log — it provides context for any physician who reviews your record.
Questions to ask your physician
- My vaginal dryness rating before starting estriol was [X]. At [N] weeks, my current rating is [Y]. Given that estriol is a weaker estrogen, is that trajectory consistent with expected response?
- I've been logging dyspareunia at [frequency and severity] — it has [improved/not improved] over [N] weeks. Does that response suggest switching to an FDA-approved estradiol product would be more effective?
- My application consistency log shows [pattern of adherence]. Does the frequency I'm applying at appear adequate for the tissue response I'm seeing?
- I'm using a compounded estriol product from [pharmacy]. Has my physician noted any quality concerns about this compounding source, and should the source be documented in my record?