Starting HRT: what side effects to expect in the first few months

You finally have the prescription. You've done the reading, had the appointment, maybe even cried a little in the pharmacy parking lot from relief. Then week one arrives with sore breasts, a headache, and some surprise spotting, and a little voice asks: is this normal, or is this a sign I should stop? Let's walk through what the first few months usually look like, so you can tell the expected bumps from the things that need a call.

The short version

Early side effects are common, usually mild, and often temporary. The NHS says estrogen and progestogen side effects "will often go away after a few weeks," and recommends continuing for at least 3 months where possible, because side effects tend to improve with time. Three months is also the timeline for benefits: symptoms can start improving within days or weeks, but it can take up to 3 months for HRT to work fully.

That doesn't mean gritting your teeth through anything. If side effects are severe, or still bothering you after 3 months, that's a reason to talk to your clinician, who may change the dose, the type of hormone, or the way you take it (for example, switching from tablets to patches).

Common side effects in the first weeks

Most HRT has two parts. Estrogen does the heavy lifting on hot flashes and night sweats. If you still have a uterus, you also take a progestogen to protect its lining. Each part has its own typical side effects, and combined HRT can bring either or both.

With patches, gels and sprays, a rash or itch can show up only where you apply the estrogen. The NHS says that is worth raising with your clinician, since a different product or route may suit you better.

Is it the HRT, or is it menopause?

Here's the tricky part: many HRT side effects look a lot like menopause itself. The NHS points out that side effects can mimic menopause symptoms, so HRT may not be the cause. Headaches, mood dips and fatigue were often on your list before you started. A simple daily note for the first 12 weeks makes it much easier to see what's actually changing. And on the question everyone asks: the NHS says there is little evidence that most types of HRT cause weight gain. (More on that in perimenopause weight gain.)

Bleeding and spotting: what's normal

Bleeding is the side effect that worries people most, and what's "normal" depends on which type of combined HRT you take.

• Sequential (cyclical) combined HRT. Usually offered if you still have periods. You take estrogen every day and add progestogen for part of each cycle. A withdrawal bleed at the end of each progestogen course is expected.
• Continuous combined HRT. Usually offered after menopause. You take both hormones every day. Irregular bleeding or spotting is common for the first 4 to 6 months.

The NHS advice: mention irregular bleeding at your first review around 3 months. Contact your clinician if irregular bleeding lasts more than 6 months after starting, if bleeding becomes heavier, or if you bleed after a long stretch without any bleeding.

What about the bigger risks?

You may have heard the news. In November 2025 the FDA asked manufacturers to remove cardiovascular disease, breast cancer and probable dementia language from the boxed warning on menopausal hormone therapy, and in February 2026 it approved the first updated labels. Two details matter here: information on heart disease and breast cancer stays in the labeling outside the box, and systemic estrogen-only products keep a boxed warning about endometrial cancer, which is exactly why a progestogen is added if you have a uterus. We unpack all of it in what changed with HRT in 2025.

The NHS describes HRT as linked to a small increase in the risk of blood clots and breast cancer. The Menopause Society says that for most healthy women with symptoms who are under 60, or within 10 years of menopause, the benefits outweigh the risks, and that skin-based estrogen (patches, gels, sprays) and lower doses may lower the risk of blood clots and stroke. These are early-weeks questions worth raising with your clinician, especially if you have a personal or family history of clots.

When to call your clinician

Get help right away (call 911 or go to the emergency room) if you have:

• Chest pain or sudden shortness of breath, which can signal a clot in the lungs or a heart problem.
• Trouble speaking or moving an arm or leg, or a face that droops on one side, which can be signs of stroke.
• Sudden swelling of the lips, mouth, throat or tongue, or trouble breathing.

Call your clinician promptly if you have:

• Pain, redness or swelling in one leg, which can be a sign of a blood clot.
• Bleeding that gets heavier, lasts beyond 6 months, or starts after months with no bleeding.
• Side effects that are severe or haven't eased after about 3 months.
• Low mood that doesn't lift. If you ever have thoughts of harming yourself, call or text 988.

Questions to ask your clinician

1. Which side effects should I expect with my specific type and route of HRT?
2. Am I on sequential or continuous combined HRT, and what bleeding pattern should I expect?
3. When is my first review, and what should I track before then?
4. If side effects don't settle, would you change the dose, the progestogen, or the route?
5. Given my history, would a patch or gel make more sense for me than a pill?
6. How will we decide whether it's working?

Bring notes to that follow-up. Our doctor visit playbook shows how to turn a few weeks of observations into a clear, five-minute conversation.

Questions

What are the most common HRT side effects in the first month?

The most common early side effects are breast tenderness, headaches, nausea, spotting or irregular bleeding, mood changes and leg cramps. The NHS says these often go away after a few weeks.

How long do HRT side effects last?

Many settle within a few weeks. The NHS suggests continuing for at least 3 months where possible, and talking to your clinician if side effects are severe or last longer than that. Irregular bleeding usually settles within 6 months.

Is spotting normal when starting HRT?

Yes, irregular bleeding or spotting is common in the first months, especially on continuous combined HRT, where it can last 4 to 6 months. Contact your clinician if it lasts beyond 6 months, gets heavier, or starts after a long time without bleeding.

How long does HRT take to work?

Symptoms can start improving within days or weeks, but the NHS says it can take up to 3 months for HRT to work fully.

Should I stop HRT if I get side effects?

Talk to your clinician before stopping. They can often fix the problem by changing the dose, the type of progestogen, or the route, such as moving from tablets to a patch. Chest pain, stroke signs or one swollen painful leg need urgent care right away.

Keep reading

• Estrogen patch vs pill (and gel): how to choose for menopause
• Progesterone in perimenopause: your uterus, your sleep, and what it can and can't do
• Is vaginal estrogen safe? What the research says, including after breast cancer
• Testosterone for women in menopause: what it can (and can't) do for low libido
• Perimenopause heart palpitations: why your heart races at night, and when to worry
• Menopause joint pain: why your joints ache in perimenopause, and what helps

Education and personal experience, not medical advice. Talk with your own clinician before making health decisions.