HRT Side Effects: What's Normal, What Fades, What to Report
Mild or no side effects are common, and those that appear, such as breast tenderness, headaches, nausea and irregular bleeding, often fade within weeks to months; the NHS suggests giving treatment at least 3 months. A GP might suggest changing the dose, type or route. Chest pain with breathlessness or signs of stroke mean calling 911.
Starting hormone therapy comes with a strange kind of worry. You've finally got a prescription for the thing that's supposed to help, and then your breasts ache, you spot when you didn't expect to, or a headache arrives that you can't place. Is that the HRT, the menopause, or something that needs a doctor?
This guide covers the side effects the NHS lists for estrogen and for progestogen, what bleeding is expected and for how long, the weight question, what your prescriber can change, and the short list of symptoms that are not ordinary side effects at all. The serious long-term risks, like blood clots and breast cancer, are a different conversation, and our HRT guide covers them.
Are HRT side effects common, and do they go away?
Mild side effects are common, and so is having none. The NHS says it's common to have no side effects or only mild ones, that any side effects usually improve over time, and that it's a good idea to carry on with treatment for at least 3 months if possible.
There's a twist that makes the first months confusing. As the NHS puts it, "side effects of HRT can be similar to menopause symptoms, so it might not be your HRT that's causing it." Hair loss is one example: the NHS notes it is sometimes a symptom of the menopause itself. I found it helpful to note when a symptom started relative to the first dose, because that's the question a prescriber is likely to ask.
What are the side effects of estrogen?
The NHS lists headaches, breast pain or tenderness, unexpected vaginal bleeding or spotting, nausea, mood changes including low mood or depression, leg cramps, mild rash or itching, diarrhea and hair loss. It says these will often go away after a few weeks. Its page on estrogen tablets, patches, gel and spray adds practical advice for each one.
| Side effect | What the NHS says usually happens | When it suggests talking to a doctor |
|---|---|---|
| Headaches | Usually last only a few days after starting; a painkiller such as ibuprofen or acetaminophen (paracetamol) may help | If they last longer than a week or are severe |
| Breast pain or tenderness | Usually improves after a few weeks | If it bothers you or doesn't go away; contact your doctor about any lump or breast change after a few months |
| Nausea | Should wear off after a few days; taking tablets with food and keeping meals simple may help | If it lasts more than a week |
| Mood changes | May last for the first few months | If it lasts longer or becomes too difficult to cope with |
| Leg cramps | Usually only the first few weeks; regular calf stretches and gentle exercise may help | If they keep coming after the first few months |
| Mild rash or itching | If it covers a large area, usually lasts about a week; a pharmacy antihistamine may help | If it doesn't go away after about a week, or affects only the area where you apply a patch, gel or spray |
The NHS page on continuous combined HRT gives a more specific window for one of these: it says breast tenderness or pain usually improves after 4 to 6 weeks.
Two details from the same page are worth knowing. If you're also taking a progestogen, some of these side effects may come from the progestogen instead, so it suggests checking the leaflets for both medicines. And hair loss, it notes, "may not always be caused by taking oestrogen, as it's sometimes a symptom of the menopause."
What are the side effects of progestogen?
The NHS lists changes in your periods including spotting or bleeding between periods, headaches, breast pain or tenderness, nausea, diarrhea, feeling tired or dizzy, mood changes including low mood or depression, mild rash or itchy skin, and acne. As with estrogen, it says these usually go away after a few weeks.
NICE recommends combined HRT, which includes a progestogen, for people with a uterus, so for many women these apply too. The NHS page on micronised progesterone (sold as Utrogestan in the UK) adds one safety note: if you feel tired or dizzy, sit or lie down until you feel better, and don't drive, cycle or use tools or machinery until it passes.
For mood changes that don't improve, it says to talk to your doctor, because you may need a different dose or type of progestogen. If you're curious why progesterone is sometimes taken at bedtime, our guide to progesterone and sleep explains it.
Is bleeding on HRT normal?
Often, yes, at least early on. The NHS says irregular bleeding or spotting is common in the first few months after starting HRT and usually settles within 6 months. What counts as expected depends on the type of HRT you take, and bleeding outside those windows needs to be checked.
- Sequential combined HRT (estrogen daily, progestogen for part of the month): the NHS says it's normal to have a withdrawal bleed at the end of each course of progestogen.
- Continuous combined HRT (both hormones every day): the NHS says irregular bleeding or spotting is common in the first 4 to 6 months.
- After a hysterectomy: the NHS says to talk to your doctor if you get any vaginal bleeding.
The NHS gives three reasons to speak to a GP: irregular bleeding for more than 6 months after starting HRT, bleeding that becomes heavier, or bleeding after you haven't had periods for a while. It says to mention irregular bleeding at your first review after 3 months, and that if it doesn't go away, the GP might suggest changing your dose of progestogen.
Bleeding that falls outside these patterns is covered in our guide to postmenopausal bleeding.
Does HRT make you gain weight?
Probably not, according to the NHS. It says there's little evidence that most types of HRT make you put on weight, and that weight gain during menopause and with age often happens whether you take HRT or not. It suggests regular exercise and a balanced diet to help manage weight.
What actually drives midlife weight change is covered in our menopause weight gain guide.
What can your prescriber change?
Quite a lot. The NHS says a GP might suggest changing your dose, the type of HRT you take, or how you take it, for example switching from tablets to patches. NICE recommends reviewing treatment at 3 months to assess how well it works and is tolerated, then yearly unless problems such as side effects call for an earlier review.
NICE also recommends referral to a healthcare professional with expertise in menopause if treatments don't improve symptoms or side effects continue. In my reading, that's useful to know if you've been told to just put up with it. The difference between tablets and patches is explained in our estrogen patch guide.
Don't stop on your own. In my reading, if a side effect is bothering you, the NHS route is a conversation with your GP about the dose, type or route, not quietly stopping. NICE notes that stopping HRT can be done gradually or all at once, and that gradually reducing may limit symptoms coming back in the short term, which is another reason to plan it with your prescriber.
Which symptoms are not ordinary side effects?
A few symptoms need attention right away rather than a wait-and-see approach. The NHS pages on estrogen and on micronised progesterone both describe serious side effects as rare, and both sort them into the same levels of urgency. The emergency signs point to a possible blood clot or stroke.
Call 999 (911 in the US) or go to the emergency department now, according to the NHS, if you have pain in your chest and breathlessness, which could be a sign of a blood clot in the lungs or heart problems, or difficulty speaking or moving your arm or leg, or your face has dropped on one side, which could be a sign of a stroke. Don't drive yourself.
Call a doctor or the NHS 111 advice line now for pain, redness or swelling in one of your legs, usually in the calf, which could be a sign of deep vein thrombosis. The micronised progesterone page adds yellowing of the whites of the eyes or the skin, which could be a sign of liver problems.
The NHS also lists signs of a serious allergic reaction that mean calling 999 (911 in the US), including sudden swelling of the lips, mouth, throat or tongue, or struggling to breathe.
Two more items are on the NHS list of reasons to speak to a GP: a lump or change in your breasts, such as dimpling of the skin or a change in the nipple, and any change in vaginal bleeding after you've been taking HRT for more than a few months. The NHS explains that these could be signs of breast cancer and womb cancer, and says it's important to keep going to breast screening appointments while you take HRT.
Where to go from here
If you're still deciding whether HRT is right for you, start with our HRT guide, which covers the benefits and the long-term risks. If vaginal symptoms are your main concern, a much lower dose may be enough, and our vaginal estrogen guide explains how little of it reaches the blood. And if you've been offered compounded hormones instead, read our bioidentical hormone guide first.
For how all of this connects to rest and recovery at night, start at the complete perimenopause and menopause sleep guide.
Key takeaways
- Mild is the norm: the NHS says it's common to have no side effects or only mild ones, and suggests giving treatment at least 3 months.
- It might not be the HRT: side effects can look like menopause symptoms, so timing relative to your first dose matters.
- Early bleeding is common: NICE says bleeding is a common side effect in the first 6 months of systemic HRT, or within 3 months of a change; unscheduled bleeding beyond that needs prompt medical help.
- Weight gain is not well supported: the NHS says there's little evidence most types of HRT cause it.
- The fix is usually a change, not stopping: dose, type or route can all be adjusted, and NICE recommends a review at 3 months.
- Know the emergency signs: chest pain with breathlessness or signs of stroke mean calling 911; pain, redness or swelling in one leg (usually the calf) means calling a doctor now.
Frequently asked questions
How long do HRT side effects last?
The NHS says side effects usually improve over time and often go away after a few weeks, so it suggests carrying on with treatment for at least 3 months if possible. It advises speaking to a GP if side effects are severe or continue for longer than 3 months.
Is bleeding on HRT normal?
Often, yes. The NHS says irregular bleeding or spotting is common in the first few months and usually settles within 6 months. NICE says bleeding is a common side effect in the first 6 months of systemic HRT, or within 3 months of a dose change, and to seek medical help promptly if unscheduled bleeding happens beyond those timeframes.
Does HRT cause weight gain?
The NHS says there is little evidence that most types of HRT make you put on weight. It notes that weight gain during menopause and with age often happens whether you take HRT or not.
Could my symptoms be menopause rather than HRT?
Possibly. The NHS points out that side effects of HRT can be similar to menopause symptoms, so it might not be your HRT that is causing them. Hair loss is one example it gives: it is sometimes a symptom of the menopause rather than of estrogen.
What can I do if HRT side effects don't go away?
Talk to your prescriber. The NHS says a GP might suggest changing your dose, the type of HRT or how you take it, for example switching from tablets to patches. NICE recommends reviewing treatment at 3 months to check how well it works and how well it is tolerated.
Which HRT side effects are an emergency?
The NHS pages on estrogen and on micronised progesterone both say to call 999 (911 in the US) or go to the emergency department for chest pain with breathlessness, or signs of stroke such as difficulty speaking or moving an arm or leg, or a face that has dropped on one side. They say to call a doctor or the NHS 111 advice line now for pain, redness or swelling in one leg.
Sources cited
- NHS. Side effects of hormone replacement therapy (HRT). Page last reviewed January 3, 2023. www.nhs.uk/medicines/hormone-replacement-therapy-hrt/side-effects-of-hormone-replacement-therapy-hrt
- NHS. Side effects of oestrogen tablets, patches, gel and spray. Page last reviewed January 5, 2023. www.nhs.uk/medicines/hormone-replacement-therapy-hrt/oestrogen-tablets-patches-gel-and-spray/side-effects-of-oestrogen-tablets-patches-gel-and-spray
- NHS. Side effects of Utrogestan (micronised progesterone). Page last reviewed January 5, 2023. www.nhs.uk/medicines/hormone-replacement-therapy-hrt/utrogestan-micronised-progesterone/side-effects-of-utrogestan
- NHS. Side effects of continuous combined HRT. Page last reviewed January 18, 2023. www.nhs.uk/medicines/hormone-replacement-therapy-hrt/continuous-combined-hormone-replacement-therapy-hrt-tablets-capsules-and-patches/side-effects-of-continuous-combined-hrt
- National Institute for Health and Care Excellence. Menopause: identification and management (NG23). Recommendations 1.8 and 1.9. www.nice.org.uk/guidance/ng23/chapter/Recommendations
How this article was checked
The NHS pages on HRT side effects, estrogen, micronised progesterone and continuous combined HRT, and NICE guideline NG23, were read in full, and every quote from them appears as written. The NHS uses UK emergency numbers (999 for emergencies, 111 for urgent advice); where it says 999, this article adds the US equivalent, 911.
An independent fact-check found no serious errors; it led to small corrections in an earlier draft, mostly to keep timing and levels of urgency exactly as the sources state them.
It has not been reviewed by a clinician. Ellen Hayes is a researcher and writer, not a doctor, and nothing here is a diagnosis or a substitute for being seen by one.
Ellen Hayes
Health & Wellness Writer and Researcher
Hi — I'm Ellen. The first few months on HRT are when most women give up on it, often over side effects that would have settled. I hope this helps you tell the ordinary ones from the few that need a call today.
I'm not a doctor. I'm not an expert — and I'm never going to talk down to you like one. I'm a woman in the middle of perimenopause who got tired of vague answers, started reading the actual research, and writes it down here in plain English, the way I'd explain it to a friend over coffee. More about Ellen →