Last checked September 2026 against 24 sources · Editorial policy
HRT side effects
The most common HRT side effects are breast tenderness, headaches, nausea, leg cramps, bloating, mood changes and irregular bleeding or spotting. They're usually mild and settle within about 3 months. Estrogen causes most of the breast and fluid symptoms; progestogen more often causes mood changes and bleeding. Serious side effects, such as blood clots, are rare, and patches and gels don't raise clot risk.
Breast tenderness, bloating, spotting and headaches are common in the first 3 months and usually settle. Serious risks by type and age, and fixes.
HRT side effects: expectation vs reality
What people often expect
“HRT side effects are severe and mean HRT isn't right for me”
What the evidence shows
Most side effects are dose-related and temporary. In Climara trials, breast pain affected 8% of women on the 0.05 mg patch and 29% on the 0.1 mg patch, compared with 4% on placebo. The NHS advises carrying on for at least 3 months if you can, because side effects usually improve, and changing the dose, the type or the route usually fixes those that don't.
HRT side effects explained
Estrogen side effects
Estrogen side effects include headaches, breast pain or tenderness, unexpected spotting, nausea, mood changes, leg cramps, a mild rash or itching, diarrhea and hair loss. The NHS says they happen in more than 1 in 100 people and often go away after a few weeks. Breast tenderness and fluid retention reflect estrogen's effect on tissue and tend to be dose-related, so a lower dose often helps.
Learn more →Progesterone and progestogen side effects
Progestogens can cause changes in bleeding, headaches, breast tenderness, nausea, diarrhea, tiredness or dizziness, mood changes including low mood, a mild rash and acne. Micronized progesterone is taken at bedtime, at least 2 hours after food, and can make you feel tired or dizzy. If one progestogen doesn't suit you, another type, a different regimen or a hormonal IUD may be better tolerated.
Learn more →Bleeding and spotting on HRT
Irregular bleeding or spotting is common for the first 3 to 6 months of HRT and usually settles. On sequential HRT, a monthly withdrawal bleed is expected. On continuous combined HRT, irregular bleeding is common in the first 4 to 6 months. Bleeding that lasts beyond 6 months, gets heavier, or starts after you'd stopped bleeding needs checking before any change is made.
Learn more →Side effects of estrogen tablets vs patches and gels
Tablets pass through the liver, which is why nausea is more of an issue with them and why they raise the risk of blood clots and gallbladder disease. In a large UK study, tablets raised clot risk (odds ratio 1.58) while patches and gels didn't (0.93). Patches and gels can cause skin irritation where they're applied instead: 3.2% or fewer women had redness or irritation in Vivelle-Dot trials.
Learn more →Serious HRT side effects and how rare they are
Serious side effects are rare. Estrogen tablets slightly raise the risk of blood clots and stroke, especially over 60. Combined HRT adds around 5 breast cancer cases per 1,000 women taking it for 5 years. Estrogen without a progestogen raises uterine cancer risk in women with a uterus. In the WHI trial, combined HRT led to 12 excess adverse events per 10,000 women a year aged 50 to 59, and 38 at 70 to 79.
Learn more →Low-dose estrogen side effects
Lower doses mean fewer side effects. Menopause guidance recommends starting low because symptoms often respond and higher starting doses are more likely to cause side effects. The Climara trials show the pattern: headaches affected 5% on 0.025 mg and 18% on 0.05 mg, and breast pain 5% and 8%, while low-dose patches weren't linked with stroke in a large study.
Learn more →HRT side effects in perimenopause
Starting HRT while you still have periods brings the same possible side effects, plus a few specific ones. Sequential HRT causes a monthly bleed, and some women feel progestogen side effects such as low mood or breast tenderness during the progestogen days. Because your own hormones still fluctuate, side effects can overlap with perimenopause symptoms, and it can take time to find the right dose and type.
Learn more →Is it HRT or menopause?
HRT side effects can look like menopause symptoms: headaches, mood changes, breast tenderness and hair loss happen in both. The NHS points out that a side effect might not be caused by your HRT at all. Keeping a simple diary of symptoms before and after starting helps you and your doctor tell them apart, and review at 3 months is the usual point to decide on changes.
Learn more →HRT side effects by the numbers
From the studies on this page
had breast pain on 0.05 mg vs 0.1 mg Climara patches, compared with 4% on placebo
8% vs 29%
3 months
3 to 6 months
1.58 vs 0.93
Side effect rates come from trials of specific products and doses. Many women have no side effects, or only minor ones.
How to reduce HRT side effects
Give HRT 3 months if side effects are mild
First stepMost side effects improve as your body gets used to the hormones, so the NHS suggests carrying on for at least 3 months if possible. Headaches often last only a few days, leg cramps a few weeks, and breast tenderness usually improves within weeks. A short diary of symptoms and side effects makes your 3-month review more useful.
Lower the estrogen dose
First stepBreast tenderness, headaches and swelling are more common at higher doses: in Climara trials, breast pain rose from 8% on the 0.05 mg patch to 29% on 0.1 mg. If your symptoms are controlled but side effects persist, a lower dose may keep the benefit with fewer side effects. Dose changes are usually made no more often than every 3 months.
Switch from tablets to patches or gel
Strong evidenceChanging the route helps nausea and removes the extra clot risk of tablets, because patches, gels and sprays don't pass through the liver first. The NHS gives switching from tablets to patches as an example of how a doctor can reduce side effects. If a patch irritates your skin, a gel or spray is another transdermal option.
Related guide →Change the progestogen
First stepIf low mood, breast tenderness or irregular bleeding seem linked to the progestogen, switching type, for example to micronized progesterone or a 52 mg hormonal IUD, can help. The IUD delivers progestogen directly to the uterus, provides excellent protection of the lining and gives good bleeding control, and it can stay in for 5 years as part of HRT.
Practical fixes for common side effects
First stepTake estrogen tablets with food if they make you feel sick, and stick to simple meals. Stretch your calves regularly for leg cramps. Try ibuprofen or acetaminophen for headaches in the first days. For a rash under a patch, rotate sites and avoid irritated skin; if a rash lasts longer than about a week, ask about a different product.
When HRT side effects need a doctor
Urgent: Pain, redness or swelling in one leg
Call a doctor now. It could be a blood clot.
Urgent: Chest pain with breathlessness, or trouble speaking, arm weakness or a drooping face
Call 911. These can be signs of a clot in the lungs or a stroke.
A breast lump or changes in your breasts
See a doctor. Keep up with mammograms while on HRT.
Bleeding after 6 months of HRT, or any bleeding after a hysterectomy
See a doctor to rule out other causes before adjusting your HRT.
More →Side effects that are severe or last longer than 3 months
Talk to your doctor about changing the dose, type or route.
HRT side effects: questions women ask
What are the side effects of HRT for women?
The common ones are breast tenderness, headaches, nausea, leg cramps, bloating, mood changes and irregular bleeding or spotting. They usually settle within 3 months. Serious effects such as clots are rare and less likely with patches or gels than tablets.
What are the side effects of estrogen tablets?
The same as other estrogen, such as breast tenderness, headaches, nausea and spotting, plus a slightly higher risk of clots, stroke and gallbladder disease than patches or gels, because tablets pass through the liver. Taking them with food helps nausea.
What are the side effects of low-dose estrogen?
The same types of side effects as higher doses, but less often. In Climara trials, headaches and breast pain were less common on the lowest-dose patch than on higher doses. Low-dose patches weren't linked with stroke.
What are the side effects of estrogen and progesterone together?
Combined HRT can cause both sets: estrogen side effects such as breast tenderness and headaches, and progestogen side effects such as mood changes, tiredness and bleeding changes. Combined HRT also adds around 5 breast cancer cases per 1,000 women over 5 years.
What are the side effects of HRT in perimenopause?
The same as at any age, and on sequential HRT, a monthly bleed and sometimes progestogen side effects during part of the cycle. Side effects can be hard to separate from perimenopause symptoms, so a symptom diary helps.
Related →Does HRT cause weight gain?
No. A Cochrane review found no difference in weight gain with HRT, and the NHS says there's no good evidence estrogen makes you put on weight. Early bloating can make you feel heavier but usually settles.
Related →Can HRT cause hair loss?
Hair loss is listed as a possible side effect of estrogen, but it's also a symptom of menopause, so HRT may not be the cause. If it worries you, talk to your doctor. Estrogen may also help hair in some women, so the effect varies from person to person.
Related →How long do HRT side effects last?
Most settle within 3 months. Headaches often last only a few days and leg cramps a few weeks. Spotting can last 3 to 6 months. If side effects are severe or last longer than 3 months, see your doctor.
What are the side effects of a progesterone patch?
Progestogen in a patch, as in CombiPatch or Climara Pro, can cause the usual progestogen effects such as bleeding changes, breast tenderness and mood changes, plus skin irritation where the patch sits. If irritation or bleeding persists beyond the first months, a separate progestogen or a hormonal IUD may suit you better.
Sources
- NHS. Side effects of hormone replacement therapy (HRT).
- NHS. About hormone replacement therapy (HRT).
- Prescribing information: Estradiol tablets USP. Teva Pharmaceuticals, 2024. DailyMed, US National Library of Medicine.
- Vinogradova Y, Coupland C, Hippisley-Cox J. Use of hormone replacement therapy and risk of venous thromboembolism: nested case-control studies using the QResearch and CPRD databases. BMJ. 2019;364:k4810.
- Prescribing information: Climara (estradiol transdermal system). Bayer HealthCare, 2026. DailyMed, US National Library of Medicine.
- NHS. Oestrogen tablets, patches, gel and spray: side effects.
- NHS. Utrogestan (micronised progesterone): side effects.
- NHS. Utrogestan (micronised progesterone): how and when to take.
- British Menopause Society. Tool for clinicians: HRT preparations and equivalent alternatives. 2024.
- NHS. Continuous combined HRT: side effects.
- Liu B, Beral V, Balkwill A, et al. Gallbladder disease and use of transdermal versus oral hormone replacement therapy in postmenopausal women: prospective cohort study. BMJ. 2008;337:a386.
- Prescribing information: Vivelle-Dot (estradiol transdermal system). Sandoz, 2023. DailyMed, US National Library of Medicine.
- NHS. Benefits and risks of hormone replacement therapy (HRT).
- Prescribing information: Divigel (estradiol gel 0.1%). Vertical Pharmaceuticals, 2026. DailyMed, US National Library of Medicine.
- Manson JE, Chlebowski RT, Stefanick ML, et al. Menopausal hormone therapy and health outcomes during the intervention and extended poststopping phases of the Women's Health Initiative randomized trials. JAMA. 2013;310(13):1353-68.
- Women's Health Concern / British Menopause Society. Fact sheet: HRT types, doses and regimens.
- Renoux C, Dell'aniello S, Garbe E, et al. Transdermal and oral hormone replacement therapy and the risk of stroke: a nested case-control study. BMJ. 2010;340:c2519.
- NHS. Sequential combined HRT: side effects.
- National 911 Program. 911.gov.
- Norman RJ, Flight IH, Rees MC. Oestrogen and progestogen hormone replacement therapy for peri-menopausal and post-menopausal women: weight and body fat distribution. Cochrane Database Syst Rev. 2000;1999(2):CD001018.
- NHS. Oestrogen tablets, patches, gel and spray: common questions.
- Gupta AK, Economopoulos V, Mann A, et al. Menopause and hair loss in women: Exploring the hormonal transition. Maturitas. 2025;198:108378.
- Prescribing information: CombiPatch (estradiol/norethindrone acetate transdermal system). Noven, 2024. DailyMed, US National Library of Medicine.
- Prescribing information: Climara Pro (estradiol and levonorgestrel transdermal system). Bayer HealthCare, 2026. DailyMed, US National Library of Medicine.
See our editorial policy.
Related guides
Estradiol side effects
Breast tenderness, nausea, bloating, headaches and spotting are the most common estradiol side effects. Which …
HRT benefits and risks
HRT relieves hot flashes, sleep and mood symptoms and protects bone. Breast cancer, clot and stroke risk depen…
Progesterone side effects
Drowsiness, dizziness, bloating, breast tenderness and mood changes are the most common. Pill and cream side e…
Does HRT cause weight gain?
Studies don't show that HRT causes weight gain. Why low estrogen shifts fat to the waist, what HRT does to bod…