Is sex hormone therapy safe for your heart?

The two main sex hormones — estrogen and testosterone — have wide-ranging effects in the body, including on the cardiovascular system. Produced primarily by the ovaries (estrogen) and testes (testosterone), these hormones affect not just your sexual function but also blood pressure, cholesterol, and other factors that influence heart health.

As people age, the natural decline in sex hormone levels sometimes causes undesirable symptoms, such as hot flashes or a flagging sex drive. Doctors can prescribe pills, patches, gels, and creams containing estrogen or testosterone to ease those symptoms. But are these products safe for your heart?

Some studies have suggested protective effects, while others have reported dangers to the cardiovascular system. But there's been far more research on estrogen, which is often given in combination with progesterone, another sex hormone. In fact, there were no long-term findings on testosterone therapy in men until this year. Here's a quick review of the current evidence on this topic.

Testosterone therapy

When men reach their mid-20s, their testosterone levels start to gradually fall. The term andropause, which refers to this age-related hormone drop, was coined back in the 1930s. But the push to treat the phenomenon is far more recent. In the early 2000s, direct-to-consumer advertisements suggested that low testosterone could make men feel tired, dull, and depressed and that testosterone therapy could restore their energy, alertness, and sexual function. This marketing trend, along with the release of an easy-to-use gel formulation of the drug, led to a sharp rise in testosterone prescriptions.

According to the American Urological Association (AUA), testosterone therapy is recommended only for men with low blood levels of testosterone (defined as less than 300 ng/dL) and symptoms, which might include a loss of muscle mass, sleep problems, and a reduced sex drive. Yet up to a quarter of men don't have their testosterone levels checked before starting treatment. And of those who do, nearly half don't get rechecked once they do start, according to the AUA, which recommends stopping the therapy if symptoms don't improve.

Several observational studies found a possible increased risk of heart-related problems from testosterone therapy in older men. As a result, in 2014, the FDA issued a warning cautioning against the practice. But the latest research offers some reassurance about testosterone's cardiovascular safety, according to Harvard Medical School professor Dr. Aria Olumi, chief of urologic surgery at Beth Israel Deaconess Medical Center.

Published July 13, 2023, in The New England Journal of Medicine, the study included more than 5,200 men who were at high risk for cardiovascular problems and had low testosterone levels. Over a follow-up period averaging nearly two years, men using testosterone were no more likely to have serious heart-related problems than those using a placebo.

Still, it's worth noting that about two-thirds of the men in both groups dropped out of the study. Plus, the report did not include information about whether testosterone therapy improved any symptoms related to low testosterone, Dr. Olumi notes.

"I see men who have been prescribed testosterone by another physician and have continued taking it for years. But they admit that they're not really sure it's doing anything for them," he says. What's more, many men have low testosterone levels and feel perfectly fine, he adds. For men with low testosterone and related symptoms, it's now considered safe to try testosterone. "But if you don't feel better after six months, there's no reason to keep taking it," says Dr. Olumi.

Estrogen therapy

In contrast to the gradual decline in hormone levels men experience, hormone levels drop rather abruptly when women reach their late 40s and early 50s. About 75% of women say they experience symptoms such as hot flashes and night sweats around the time of menopause. Some have only mild, occasional symptoms. But others are so uncomfortable and debilitated that the experience impairs their sleep, mood, and day-to-day function.

 Hormone therapy can ease menopausal symptoms, but lingering concern about possible heart-related risks — documented in a major trial published in 2002 — has left some doctors reluctant to prescribe the therapy.

"It's a conundrum that comes up fairly often, because all women go through menopause," says Dr. Emily Lau, a cardiologist at Massachusetts General Hospital who specializes in women's cardiovascular health. Research over the past two decades has painted a clearer picture of the cardiovascular risk, which depends on the timing and type of hormone therapy a woman takes, as well as her own underlying risk of heart disease, she says. (To assess your 10-year risk, see /heartrisk).

First, women shouldn't start taking systemic hormone therapy (that is, in pill or patch form) after age 60 or more than 10 years after menopause begins. Second, women should use the lowest possible dose of hormones to ease their bothersome symptoms and ideally re-evaluate the need for the therapy every year, according to Dr. Lau, who co-authored an in-depth article about menopausal hormone therapy in the Feb. 14, 2023, issue of Circulation.

For healthy women with a low 10-year heart disease risk (less than 5%), all forms of hormone therapy are acceptable. But for those with a risk of 5% to 10%, experts recommend transdermal patches, which are less likely to trigger blood clots than hormones taken in pill form. Women at high risk (greater than 10%) should avoid systemic hormone therapy if possible.

A new, nonhormonal drug called fezolinetant (Veozah) for treating hot flashes and night sweats could be a good alternative, says Dr Lau. Finally, it's worth noting that vaginal estrogen products (creams, suppositories, and rings), which can relieve vaginal dryness and discomfort during sex, do not appear to be linked to any increased heart risks.

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