Most women older than 65 don't need to stop hormone therapy, new study finds. Here's what you need to know.

Hormone therapy (HT) has been a controversial topic with women and even some doctors after a damning and controversial early 2000s study linked the treatment for menopause symptoms to an increased risk of several cancers and heart disease. While that research is now seen as flawed, there has been a lot of hesitation for both doctors and women in menopause to use this form of therapy, especially after the age of 65.

Now, new research finds that women who use hormone therapy after age 65 are usually fine to do just that — but the dose and timing of the treatment matter. The study, which was published in Menopause, the journal of The Menopause Society, analyzed data from 10 million senior women on Medicare between 2007 and 2020. The researchers concluded that potential risks of using hormone therapy after age 65 vary by the type, route and dose women take.

As a result, the researchers concluded that there should be no general rule for women stopping hormone therapy based on age alone. They also found that continuing hormone therapy beyond age 65 can be helpful for combating symptoms of menopause. Low-dose and non-oral forms of hormone therapy can also be increasingly important as women age, the study found.

Hormone therapy is considered the most effective treatment option for managing intense symptoms linked with menopause, including hot flashes. However, it’s an underutilized treatment: Research has found that just 6.86% of women had a prescription for HT in 2020.

Here’s what you need to know about hormone therapy, including the latest findings.

What is hormone therapy?

Hormone therapy, which is also referred to as hormone replacement therapy (HRT), involves taking estrogen and in some cases also progestin to replace hormones that your body loses during menopause, according to the American College of Obstetricians and Gynecologists (ACOG).

ACOG notes that hormone therapy is the best treatment for intense symptoms of menopause, including hot flashes, night sweats, vaginal dryness and bone loss.

What is the controversy around hormone therapy?

Preliminary results published in 2003 from the Women’s Health Initiative clinical trial linked a combination of estrogen and progestin with an increased risk of heart disease, stroke, blood clots, dementia and breast cancer. As a result of this association, the study was stopped early.

However, while the medical community and many women shunned hormone therapy as a result, the findings were later discredited. As researchers later discovered, the original research studied women who were 65 and up who already had a greater risk of heart attack, stroke, blood clots and more. As a result, it skewed the data. The study also didn’t analyze important information, like how old these women were when they started taking hormone therapy.

Since then, research has found that taking estrogen with a particular form of progesterone (medroxyprogesterone acetate) may increase the risk of breast cancer, but there was no effect when women took estrogen alone. A form of progesterone called micronized progesterone can also be helpful — it’s not linked with breast cancer.

“There has been a lot of holdover from the Women's Health Initiative study — it scared everybody, but it was poorly designed,” Dr. G. Thomas Ruiz, a lead ob-gyn at MemorialCare Orange Coast Medical Center in Fountain Valley, Calif., tells Yahoo Life. “It really did a disservice to the concept of hormone replacement therapy.”

As a result, “Women have been very confused about the benefits or potential consequences of hormone therapy,” women’s health expert Dr. Jennifer Wider tells Yahoo Life.

Health benefits of hormone therapy

Again, ACOG says that hormone therapy is the most effective way to prevent or minimize uncomfortable side effects of menopause. However, it has additional perks.

A study published in 2023 found that people who started hormone therapy around the time they started menopause didn’t have an increased risk for developing tau proteins in the brain — a hallmark of Alzheimer’s disease. The researchers concluded that this suggests HT may lower the risk of developing Alzheimer’s disease with age.

The latest study in the journal Menopause found that using estrogen monotherapy — in other words, just taking estrogen alone — was linked with significant reductions in risk for mortality, breast cancer, lung cancer, colorectal cancer, congestive heart failure, venous thromboembolism (when a blood clot forms in a vein), atrial fibrillation, acute myocardial infarction (aka, a heart attack) and dementia.

People who used a combination of estrogen and progestogen therapy had an increased risk of breast cancer, but that was dampened when patients took low doses of transdermal (as in, through a patch) or vaginal progestin. Using progestin in hormone therapy also led to significant risk reductions in endometrial cancer, ovarian cancer, ischemic heart disease, congestive heart failure and venous thromboembolism, the researchers found.

What experts think about the study

Dr. Lauren Streicher, clinical professor of obstetrics and gynecology at Northwestern University Feinberg School of Medicine, calls the research "added reassurance." She tells Yahoo Life: “The data is very solid that, for the overwhelming majority of women, hormone therapy will have short-term and long-term benefits. Menopause experts have been saying for a long time that you don't stop hormone therapy at a certain age.”

Dr. Jessica Shepherd, gynecologist, menopause expert and founder of Modern Meno, agrees. “These findings are extremely important for women who have been menopausal for some time, as they have been told they cannot take hormone therapy any longer,” she tells Yahoo Life.

In general, according to the Mayo Clinic, if hormone therapy is started before the age of 60 or within 10 years of menopause, “the benefits appear to outweigh the risks.”

While research has found that hormone therapy is often helpful for women in menopause, the messaging hasn’t gotten out to many women — and doctors, Shepherd notes. “The goal is to educate and make women aware of its potential benefits in their symptom relief and prevention for long-term complications,” she says.

It’s important to point out that hormone therapy requires a prescription. If your health care provider won’t prescribe it to you because you’ve “aged out” of the treatment, Ruiz recommends seeking a second opinion from an ob-gyn or doctor who specializes in the treatment of menopause.

Streicher agrees. “Don’t try to convince your doctor,” she says. “Instead, you need to see someone who knows what they're doing.”