Medically reviewed by Dr Rachel Hines, MBChB, MRCGP, DFSRH, DRCOG – Updated 8 August 2024
Like all medications, HRT can have side effects. These vary from person to person, and can depend on the dose and type of HRT used.
Read on to find out more about the side effects of HRT, and what can be done to minimise them.
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What are side effects?
All medications have some side effects. These are unwanted symptoms that you could experience when taking a new medicine. It’s difficult to predict who will experience side effects and who won’t. This means it’s important that you always read the label of any medication you start to make sure that you are aware of the possible side effects.
Often, side effects will stop after a short time as your body adjusts to the new medication. If you do get side effects, and they’re relatively mild, track them to make sure they don’t get worse. If you experience severe or persistent side effects on a new medication, speak to a healthcare professional.
The side effects of HRT
HRT, like other medications, does have some side effects and these are thought to be quite common. One study of just under 5000 HRT users found that 43% were affected.
Side effects from HRT depend on a number of factors:
- Hormones taken – oestrogen or progesterone
- Dose
- Route – systemic, transdermal or vaginal
- Your own body’s response
Side effects are least common with vaginal HRT because the hormones used are absorbed only into the vagina and nearest tissues, rather than into the bloodstream as with systemic HRT. But vaginal HRT only treats vaginal symptoms of menopause and will not help with more general symptoms like hot flushes, sleep problems and mood changes.
Learn more about vaginal HRT here.
What are the side effects of oestrogen?
Oestrogen is a key component of HRT and most of the symptoms of menopause are caused by decreased levels of this hormone. HRT supplies the oestrogen that your body no longer makes for itself, and therefore helps to improve your symptoms.
Oestrogen can be taken:
- Systemically – distributed throughout the body
- Vaginally – hormones are applied to and stay in the genital area, resulting in fewer side effects
Common side effects of systemic oestrogen (pills, patches, sprays and gels) include:
- Bloating
- Swelling
- Breast tenderness or swelling and nipple sensitivity
- Feeling sick
- Leg cramps
- Headaches
- Indigestion
- Vaginal bleeding
Irregular bleeding is common in the first 4-6 months of starting HRT, affecting up to 40% of women. If you are having frequent or heavy bleeding, see your doctor.
What are the side effects of progesterone?
You need to take progesterone as part of your HRT regimen if you still have your womb. Progesterone is important as it protects the womb’s lining (endometrium) from the effects of oestrogen. If oestrogen is taken alone, it can cause abnormal thickening and even cancer of the womb lining. Taking progesterone alongside it reduces this risk. If you do not have your womb, you don’t usually need to take progesterone. However, if you have had a hysterectomy (womb removal) due to endometriosis, you may be advised to take progesterone as well.
Common side effects of progesterone HRT include:
- Breast tenderness
- Swelling in parts of the body
- Mood swings and feelings of low mood
- Abdominal pain
- Vaginal bleeding
- Acne
What are the side effects of vaginal HRT?
Of all the different types of HRT, vaginal HRT has the lowest number of side effects. This is because the hormones used stay in and around the vaginal and genital areas, rather than being distributed throughout the body as with systemic HRT.
Vaginal HRT is useful and effective for treating symptoms of menopause which affect the vagina and urinary tract, including pain, itch, dryness, painful sex and recurrent UTIs. These are collectively known as the genitourinary syndrome of menopause (GSM) although you might also hear them referred to as vaginal atrophy or atrophic vaginitis.
Side effects are most common in the first few weeks of use as some of the hormones are absorbed into the bloodstream through the dry and damaged vaginal wall. However, this stops as soon as the vaginal HRT starts working and the vaginal tissues become healthier.
Some side effects include:
- Breast tenderness
- Increased vaginal discharge, bleeding or spotting
- Irritation or itching of the skin in or around your vagina when you start to use vaginal estrogen. This usually gets better after a few weeks.
- Headaches
- Stomach pain or feeling sick
- Flu-like symptoms
How long do HRT side effects last?
HRT side effects generally get better within three months of starting the medication. This happens as your body adjusts to the hormones contained in your HRT.
Some lucky people will have few or no side effects, and many find that side effects actually settle within a few days or weeks. However, if you’re still having side effects by the three-month mark, let your doctor know in case they can suggest other treatments.
How can you reduce HRT side effects?
If you have side effects that are bothering you, there are a few different approaches you can take to improve them.
If you take your HRT as a pill, try:
- Taking it alongside food to reduce any nausea or digestive side effects
- Taking it at a different time of day (like just before bed). For example, Utrogestan, a type of oral progesterone tablet, should be taken in the evening, either one hour before food or two hours after
General measures include:
- Exercising regularly and gentle stretching if leg cramping is an issue
- Putting your feet up if you’ve noticed leg swelling
- Eating a healthy, balanced diet
If you’re still struggling, your doctor may recommend a change to your HRT prescription. They may consider:
- Switching the way your HRT is delivered e.g. from a pill to a patch
- Reducing your oestrogen dose
- Changing the type of hormone in your HRT e.g switching from a synthetic form of progesterone to micronised progesterone
- If you’re on cyclical HRT (which gives you regular period-like bleeds), changing how much progesterone you take in each cycle
- Changing the way you take progesterone e.g. cyclical to continuous. Read more about cyclical and continuous HRT
Read more about the different types of HRT.
Start your free online menopause assessment to see if HRT is right for you
When should you see a doctor?
It can sometimes be tricky to decide whether your symptoms are side effects of HRT or signs of another medical problem. If you’re unsure, worried or suffering from severe symptoms, see your GP.
See a doctor urgently if you have any:
- Vaginal bleeding if it has been over 1 year since your last period (known as postmenopausal bleeding)
- Bleeding after sex
- Breast lumps or other changes (how to check your breasts)
- Any severe pain
- Any new or severe headaches, headaches which wake you from sleep, or headaches with any other associated symptoms – including vision changes, balance problems and weakness)
- Leg swelling, tenderness or redness – these could be signs of deep vein thrombosis, known as DVT
- Chest pain or breathlessness – these could be signs of a pulmonary embolism, known as PE
- Depression with thoughts about harming yourself or others
- Any other persistent, severe or worrying symptoms
For a full list of what to look out for, check the patient information leaflet in your HRT pack.
Final word
While side effects of HRT are common initially, it’s worth persevering. For most people, these side effects pass within a few weeks or months. If you’re struggling, see your doctor for further advice.
Find out more about menopause on our blog or in our symptoms library.
NHS, ‘Hormone Replacement Therapy (HRT) – Side Effects‘
Mayoclinic.org, Estrogen (Vaginal Route) Side Effects – Mayo Clinic
Kjersti Bakken, Anne Elise Eggen & Eiliv Lund, 2004, Side-effects of hormone replacement therapy and influence on pattern of use among women aged 45-64 years, The Norwegian Women and Cancer (NOWAC) study 1997, Acta Obstetricia et Gynecologica Scandinavica, vol. 83, no.9, pp. 850-856
Hillard, T. et al (2017). Management of the Menopause. ed. London: British Menopause Society, pp. 59-62, 73-76 and 88
The British Menopause Society, ‘Progestogens and endometrial protection’
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