In this article
If you have been reading about hormone therapy, you have probably run into the phrase "the window." It refers to a simple idea backed by a lot of research: when you start hormones seems to change how the benefits and risks balance out. This guide explains where the window comes from, what the big studies actually measured, and what your options look like if you are already past it.
The short answer
The Menopause Society's 2022 position statement says that for women younger than 60, or within 10 years of menopause onset, who have no contraindications, the benefit-risk ratio is favorable for treating bothersome hot flashes and preventing bone loss [1]. For women who start more than 10 years after menopause or after 60, the ratio appears less favorable because of greater absolute risks of coronary heart disease, stroke, blood clots, and dementia [1].
The FDA lands in the same place. When it announced changes to hormone therapy labels in November 2025, it said its labeled recommendation would be to start systemic hormone therapy within 10 years of menopause onset or before age 60 [4]. It added that timing and duration are decisions made between you and your prescriber [4].
MedlinePlus, from the US National Library of Medicine, puts it plainly: hormone therapy is safest when taken before 60 or within 10 years after menopause starts, and beginning estrogen more than 10 years after menopause does increase the risk of heart disease [5].
Where the timing window came from
The story starts with the Women's Health Initiative (WHI), two large randomized trials that tested hormone pills against placebo in 27,347 women aged 50 to 79 [2]. Their average age at the start was 63 [2]. That matters, because the average age of menopause is about 52 [1]. The FDA noted that the WHI participants were over a decade past the average age of menopause [4].
The WHI also tested only one way of taking hormones: an oral pill of conjugated equine estrogens, with or without medroxyprogesterone acetate [1]. And it enrolled relatively few women under 60 with bothersome hot flashes, the very group hormone therapy is mainly used for today [1].
When researchers later broke the results down by age, a pattern appeared. Here is what an 18-year follow-up of both WHI trials, published in JAMA in 2017, found for death from any cause [2]:
| Age when starting | During the treatment years | After 18 years of follow-up |
|---|---|---|
| 50 to 59 | 0.69 (31% lower) | 0.89 (not statistically significant) |
| 60 to 69 | 1.04 (no clear difference) | 0.98 (no clear difference) |
| 70 to 79 | 1.13 (no clear difference) | 1.03 (no clear difference) |
Overall, hormone therapy taken for a median of 5.6 years (combined) or 7.2 years (estrogen alone) was not associated with a higher risk of death from any cause, heart disease, or cancer over 18 years [2]. Death from any cause was 27.1% in the hormone groups and 27.6% in the placebo groups [2]. The age differences were clearest during the years women were actually taking the pills, and they faded with long follow-up [2].
What other studies found
The WHI was not the only evidence. The Menopause Society's statement summarizes pooled analyses of randomized trials [1]:
- Started within 10 years of menopause: a 2015 Cochrane review found lower coronary heart disease and lower all-cause mortality, no increase in stroke, but a higher risk of blood clots [1].
- Started more than 10 years after menopause, or after 60: the same review found no effect on heart disease or death, but a higher risk of stroke and blood clots [1].
- A 2020 meta-analysis found similar results for older starters: no effect on heart disease or death, but higher risk of stroke and blood clots [1].
The ELITE trial: looking at the arteries
One trial was designed specifically to test timing. ELITE randomized 643 healthy postmenopausal women to oral estradiol 1 mg a day or placebo [3]. Women were grouped by time since menopause: under 6 years, or 10 years or more [3]. Women with a uterus also used a progesterone vaginal gel for part of each cycle [3].
After a median of 5 years, the researchers measured the thickness of the carotid artery wall, a marker of early hardening of the arteries [3]. In the early group, the artery wall thickened more slowly on estradiol than on placebo. In the late group, the rates were similar [3]. On heart CT scans, there was no significant difference between estradiol and placebo in either group [3].
That is an important nuance. ELITE measured artery walls, not heart attacks. It supports the idea that timing matters, but it does not show that starting early prevents heart disease. Hormone therapy is not approved for preventing heart disease [1].
What the window means if you are inside it
Being under 60 or within 10 years of menopause does not mean hormone therapy is right for you. It means the research is most reassuring for your group. The Menopause Society says the absolute added risks for women under 60 are rare, which it defines as fewer than 10 cases per 10,000 women per year [1]. It also says your personal and family risk of heart disease, stroke, blood clots, and breast cancer should be considered before starting [1].
The Menopause Society's patient guidance notes that experts agree hormone therapy helps control moderate to severe symptoms like hot flashes when started within 10 years of menopause or under 60 [6]. If you are at high risk of broken bones or had early menopause, you may be able to take hormones earlier or longer [6].
Some things to know when you start:
- Lower doses can take time. Low-dose pills or patches may take 6 to 8 weeks to bring enough relief [1].
- Dose and route are personal. The statement recommends the appropriate, often lowest, effective dose, chosen individually and reassessed over time [1].
- A uterus needs protecting. If you have one, systemic estrogen is paired with a progestogen [1].
Still having periods? Starting in perimenopause raises a few extra questions about bleeding and birth control. See HRT for perimenopause.
What if you are starting later?
The window is not a hard cutoff. The Menopause Society says starting after 60, or more than 10 years after menopause, has complex risks and needs careful consideration, and it recognizes that some well-counseled women over 60 choose to start or restart hormone therapy [1]. In the WHI, starting after 70 carried the highest risk [1]. The statement describes risks as appearing greater for women 70 and older, or more than 20 years past menopause [1].
If hot flashes appear for the first time many years after menopause, the statement says they need further evaluation [1]. They can come from estrogen loss, but also from other conditions, such as sleep apnea or an overactive thyroid, or from medications [1]. That is worth ruling out before treating them with hormones.
Vaginal symptoms are a different story. For dryness and related symptoms, low-dose vaginal estrogen may be considered at any age [1]. Read more in our vaginal estrogen cream guide.
And if you started inside the window and are wondering how long you can stay on hormones, that is a separate question. See how long can you take HRT.
Early or premature menopause is different
If your periods stopped before 40, or earlier than average, the timing research above was not about you. The WHI did not include women with early or premature menopause, and its results in older women do not apply to them [1]. For these women, The Menopause Society recommends hormone therapy, unless there is a reason not to, at least until the average age of menopause, around 52 [1]. Talk with a clinician who knows your history.
Talking about timing with WarriorBabe Health
When you complete an intake, a WarriorBabe Health clinician looks at your age, how long it has been since your last period, your symptoms, and your personal and family history before deciding whether hormone therapy makes sense. Options include oral estradiol, an estradiol patch, estradiol cream, and a progesterone capsule. Our hormone products are compounded by a licensed pharmacy and are not FDA-approved; FDA-approved versions also exist.
Want to see if hormone therapy could be an option? Take the 2-minute quiz. For the full safety picture, read is HRT safe?
Frequently asked questions
Is it too late to start HRT at 60?
Not automatically. The Menopause Society says starting after 60 or more than 10 years after menopause needs careful consideration of your own benefits and risks, and some well-counseled women over 60 do choose to start [1]. The absolute risks of heart disease, stroke, blood clots, and dementia are higher in that group [1].
What is the 10-year rule for HRT?
It is shorthand for the finding that the benefit-risk balance looks most favorable when hormone therapy starts within 10 years of menopause or before 60 [1]. The FDA's labeled recommendation for systemic hormone therapy uses the same window [4]. It is a guide for weighing risk, not a hard deadline.
Does starting HRT early protect your heart?
That has not been shown. Some studies found lower heart disease in women who started early [1], and the ELITE trial found slower artery-wall thickening on estradiol in recent starters [3]. But ELITE found no difference on heart CT scans [3], and hormone therapy is not approved to prevent heart disease [1].
Can I start HRT before my periods stop?
Often, yes. Hot flashes may begin during perimenopause, and hormone therapy is the gold standard for relieving them [1]. A few things differ, like bleeding and the need for birth control. Our guide to HRT for perimenopause explains them.
I had early menopause. Do the age rules apply to me?
Not in the same way. The WHI did not include women with early or premature menopause, and its findings in older women do not apply to them [1]. The Menopause Society recommends hormone therapy for these women, unless there is a reason not to, at least until about age 52 [1].
References
- The 2022 hormone therapy position statement of The North American Menopause Society. Menopause. 2022;29(7):767-794. menopause.org/wp-content/uploads/professional/nams-2022-hormone-therapy-position-statement.pdf
- Manson JE, Aragaki AK, Rossouw JE, et al. Menopausal hormone therapy and long-term all-cause and cause-specific mortality: the Women's Health Initiative randomized trials. JAMA. 2017;318(10):927-938. pmc.ncbi.nlm.nih.gov/articles/PMC5728370/
- Hodis HN, Mack WJ, Henderson VW, et al. Vascular effects of early versus late postmenopausal treatment with estradiol. N Engl J Med. 2016;374(13):1221-1231. pmc.ncbi.nlm.nih.gov/articles/PMC4921205/
- US Food and Drug Administration. HHS advances women's health, removes misleading FDA warnings on hormone replacement therapy. News release, November 10, 2025. www.fda.gov/news-events/press-announcements/hhs-advances-womens-health-removes-misleading-fda-warnings-hormone-replacement-therapy
- MedlinePlus Medical Encyclopedia. Deciding about hormone therapy. US National Library of Medicine. Reviewed 3/17/2026. medlineplus.gov/ency/patientinstructions/000694.htm
- The Menopause Society. Hormone therapy. Menopause Topics, patient education. menopause.org/patient-education/menopause-topics/hormone-therapy
This article is for general information. It is not medical advice and does not replace a visit with a licensed clinician who knows your history. Do not start, stop or change a medication without talking to your clinician. If you think you are having a medical emergency, call 911.
