Hormone replacement therapy (HRT) is a treatment that supplements hormones your body has stopped making in sufficient quantities. It is most commonly used to relieve menopause symptoms by replacing estrogen and, when needed, progesterone, but it also includes testosterone therapy for men with low levels and hormone therapy as part of gender-affirming care. The specifics of treatment vary widely depending on why you need it, what form you take, and your personal health history.
How HRT Works in the Body
When hormone levels drop, whether from menopause, a medical condition, or surgical removal of the ovaries or testes, the body loses signals it depends on for dozens of functions. Estrogen, for example, helps blood vessels relax by triggering the production of nitric oxide, a molecule that widens arteries. This effect begins within minutes of estrogen entering the bloodstream. Over hours and days, estrogen also drives longer-term changes in gene expression that protect the cardiovascular system, maintain bone density, and regulate temperature.
HRT delivers these hormones from an outside source, essentially picking up where the body left off. The replacement hormones bind to the same receptors your natural hormones used, restoring the chemical signals that keep those systems functioning.
Menopause: The Most Common Use
Most people searching for HRT are thinking about menopause. As estrogen production declines, typically in your late 40s to early 50s, symptoms like hot flashes, night sweats, vaginal dryness, sleep disruption, and mood changes can range from mild to debilitating. HRT is the most effective treatment for moderate to severe hot flashes, and experts generally agree it works best when started within 10 years of menopause onset or before age 60.
The type of HRT you receive depends on whether you still have a uterus. Estrogen taken alone stimulates the uterine lining, which raises the risk of endometrial cancer over time. Adding a progestogen (a synthetic form of progesterone) counteracts that risk, bringing it back down to roughly the level seen in women not taking any hormones. If you’ve had a hysterectomy, you can take estrogen by itself.
Diagnosis is usually straightforward. Blood tests aren’t always necessary because menopause is often diagnosed based on age and symptoms alone. When there’s uncertainty, a provider may check levels of follicle-stimulating hormone (FSH), which rises during menopause, and estradiol, which falls. Thyroid-stimulating hormone is sometimes tested too, since an overactive thyroid can mimic menopause symptoms.
Forms of Estrogen Therapy
HRT comes in several delivery methods, and the choice matters for more than convenience. Oral tablets are the most traditional option, but they pass through the liver before reaching the rest of the body. This “first-pass” effect can increase the production of clotting factors, which is one reason oral estrogen carries a higher risk of blood clots than other forms.
Transdermal options, including patches applied once or twice weekly, daily gels, and sprays, deliver estrogen directly through the skin into the bloodstream, bypassing the liver entirely. Studies show better adherence with transdermal preparations compared to oral ones, likely because of the simpler routine and fewer side effects. For women concerned about clot risk, transdermal estrogen is generally the preferred route.
Local estrogen is a third category, designed specifically for vaginal dryness and urinary symptoms. Vaginal creams, pessaries, and rings deliver very small doses of estrogen directly to the tissue that needs it, with minimal absorption into the rest of the body. These are sometimes used alongside systemic therapy or on their own for women whose primary complaint is vaginal or urinary discomfort.
How Quickly Symptoms Improve
Most women notice improvement in hot flashes and night sweats within a few weeks of starting HRT, though it can take up to three months to feel the full benefit. Vaginal dryness tends to respond more slowly, often requiring several weeks of consistent use before the tissue rebuilds moisture and elasticity. Your provider will typically reassess your symptoms and dosage after about three months to fine-tune the treatment.
Risks and Safety Profile
The risks of HRT are real but often smaller than people assume. The increased risk of breast cancer is less than one additional case per 1,000 women per year of use. That’s comparable to the added risk from drinking two alcoholic beverages daily, being obese, or having a sedentary lifestyle. The risk is higher with combination therapy (estrogen plus a progestogen) than with estrogen alone. With combination therapy, the risk begins to rise after about 3 to 5 years. With estrogen alone, the increase doesn’t appear until around 7 years of use.
Both estrogen-only and combination therapy slightly increase the risk of stroke, though this risk reverses soon after stopping treatment. Blood clot risk is also elevated, particularly with oral formulations. Transdermal estrogen appears to carry less clot risk, which is why it’s often recommended for women with additional risk factors like obesity or a family history of clots.
For healthy women under 60, or within 10 years of menopause, the benefits of HRT on heart disease risk and overall mortality generally outweigh the small increases in breast cancer, blood clots, and stroke risk.
Who Should Not Take HRT
Systemic hormone therapy is generally not recommended for women who have had breast or endometrial cancer, a stroke, a heart attack, blood clots, or liver disease. Women who are pregnant or may become pregnant should not use it. Those with a history of hormone-sensitive breast cancer are advised to try nonhormonal alternatives for menopause symptoms first. Low-dose vaginal estrogen, because it delivers so little hormone systemically, is sometimes still an option for some of these women, but that’s a conversation to have with a provider who knows your full history.
Testosterone Therapy for Men
HRT isn’t only for menopause. Men whose bodies don’t produce enough testosterone, a condition called hypogonadism, may benefit from testosterone replacement. Diagnosis requires both symptoms (fatigue, low libido, reduced muscle mass, depressed mood) and consistently low blood levels. The Endocrine Society defines the lower limit of normal testosterone at 264 ng/dL in healthy, nonobese young men. Treatment aims to bring levels into the mid-normal range using gels, patches, or injections.
Testosterone naturally declines with age, but age-related decline alone doesn’t automatically warrant treatment. The threshold for therapy is a combination of measurable deficiency and symptoms that meaningfully affect quality of life.
Gender-Affirming Hormone Therapy
Hormone therapy is also a core part of medical care for transgender and gender-diverse individuals. Feminizing therapy typically involves estrogen (sometimes combined with medications that suppress testosterone), while masculinizing therapy uses testosterone. The goal is to bring hormone levels in line with a person’s gender identity, producing physical changes such as breast development, fat redistribution, voice deepening, or facial hair growth depending on the direction of treatment.
Monitoring during gender-affirming care includes regular blood work to track hormone levels and screen for side effects. Transgender individuals on estrogen therapy receive the same breast cancer screening recommendations as cisgender women. Anyone with a cervix continues to need cervical cancer screening regardless of gender identity. Bone density can be lower in some transgender individuals even before starting hormones, so physical activity and vitamin D supplementation are often encouraged alongside therapy.
Deciding Whether HRT Is Right for You
The decision to start hormone therapy is personal and depends on the severity of your symptoms, your age, how recently menopause began, and your individual risk factors for heart disease, stroke, blood clots, and breast cancer. For many women, the relief from disruptive symptoms and the protective effects on bone and cardiovascular health make it worthwhile. For others, the risk profile tips the balance toward nonhormonal alternatives. The key variables are timing (closer to menopause onset is safer), delivery method (transdermal carries fewer clot risks than oral), and the specific hormone regimen (estrogen alone versus combination therapy). These aren’t one-size-fits-all decisions, and they benefit from periodic reassessment as your health and symptoms evolve over time.