Hormone therapy: what you need to know

Few topics in women's health have generated as much confusion as hormone therapy. For over twenty years, women have received contradictory messages: that hormones are dangerous, that hormones are safe, that they should be avoided at all costs, or that they are the best thing available. The truth lies somewhere in between, and it has become much clearer in recent years. Here is what you need to know to make informed decisions together with your doctor.

What is hormone therapy?

Hormone therapy, also called menopausal hormone therapy, involves supplying the body with the hormones that the ovaries gradually stop producing. Oestrogen is the main ingredient, because it is the drop in oestrogen that causes most menopause symptoms. Women who still have their uterus also need a progestogen to protect the uterine lining. Women who have had a hysterectomy can use oestrogen alone.

The treatment comes in several forms. Tablets are the most traditional option, but today patches or gel applied to the skin are often recommended. The reason is that oestrogen taken orally passes through the liver first, which can affect the blood's clotting ability. Oestrogen through the skin bypasses this and, according to research, carries no increased risk of blood clots compared with not using hormones at all. For vaginal symptoms, there are also local preparations such as creams or pessaries, which work exactly where they are needed and are barely absorbed into the rest of the body.

What happened in 2002?

To understand the current situation, we need to rewind to the study that changed everything. In 2002, the Women's Health Initiative, a large American study, published results showing that combined hormone therapy increased the risk of breast cancer and heart disease. The study was stopped early, and the headlines were dramatic. Millions of women worldwide stopped taking hormones almost overnight, and doctors became unsure of what to recommend.

But when researchers began to look more closely at the numbers, the picture looked different. The participants in the study had an average age of 63, many were overweight, and most had started hormone therapy more than ten years after menopause. These women were simply not representative of the woman visiting her doctor with hot flushes in her late forties.

The actual increase in breast cancer risk was 8 extra cases per 10,000 women per year. That is a real risk, but far from the catastrophe the headlines suggested. And in the part of the study where women received only oestrogen without a progestogen, 20 years of follow-up showed no increased risk of breast cancer at all.

What do we know today?

Knowledge has advanced enormously since 2002. In December 2025, the American FDA removed the strong warning that had appeared on all hormone preparations since the WHI study. This was not an impulsive decision but the result of over two decades of new research. Norwegian medical professionals have pointed out that this aligns with the practice already followed in Norway.

One of the most important concepts today is the so-called timing hypothesis. Research shows that hormone therapy started within ten years of menopause, or before the age of 60, produces entirely different results from therapy started late. Early initiation is associated with reduced risk of heart disease and lower overall mortality. Late initiation, on the other hand, may increase the risk of cardiovascular disease because atherosclerotic processes have already begun.

In Norway, the trend has been clear. The number of Norwegian women over 40 using systemic hormone therapy rose from roughly 198,000 in 2019 to around 295,000 in 2024. That means prescriptions nearly doubled in five years, reflecting growing confidence among both doctors and patients.

Benefits and risks

Hormone therapy is the most effective treatment for hot flushes and night sweats, with a documented reduction of about 77 per cent in a large review of studies. It also improves sleep, can stabilise mood, and reduces the risk of osteoporosis by 20 to 40 per cent at all skeletal sites.

But the treatment is not without risk, and it is important to be honest about that. Combined hormone therapy with daily progestogen carries a certain increase in breast cancer risk with long-term use. Over a 20-year period, the risk rises from roughly 63 to 83 per 1,000 women, meaning about 20 extra cases per 1,000. With intermittent progestogen the increase is somewhat lower, and with oestrogen alone it is very small. For most women who start treatment close to menopause and use it for a limited period, the absolute risk is low.

Regarding blood clots, the picture is clear: patches and gel carry no increased risk compared with women who do not use hormones. Tablets carry a certain increase. If you have risk factors for blood clots, your doctor will recommend oestrogen through the skin.

Who can use it, and who should not?

Most women with bothersome menopausal symptoms can use hormone therapy safely, especially if they start within ten years of menopause. Women with premature menopause, meaning their last period before the age of 40, are recommended hormone therapy regardless of symptoms because they need protection against osteoporosis and heart disease.

The treatment is not recommended for women with hormone-dependent breast cancer, uterine cancer, active blood clots, severe liver disease, or unexplained vaginal bleeding. The list of precautions used to be much longer, but today's guidelines are more nuanced and allow for individual assessment in most cases.

How long can you use it?

Current guidelines have moved away from setting a fixed time limit. The principle is the lowest effective dose for as long as it is needed, with an annual review by your doctor. For some women that is a few years, for others it is longer. Local oestrogen treatment for vaginal dryness can be used as long as there is a need, with no upper limit.

The key takeaway

Hormone therapy is neither a universal miracle cure nor something to fear. It is a well-documented tool that helps many women enjoy a better quality of life through menopause. The decision should be made together with your doctor, based on your symptoms, your medical history, and your values. The most important thing is that you have access to up-to-date information, so that the choice you make is an informed one.