Hormone replacement therapy (HRT) is one of the most effective ways to relieve menopause symptoms like hot flushes, sleep disturbances, brain fog and low mood. By replacing the hormones that naturally decline during this time, HRT can help restore balance, comfort, and well-being.
As with any form of medication, it can come with side effects. While many women experience none, or only mild, short-term symptoms, others may find that their body needs a little time to adjust.
Understanding the potential side effects of hormone replacement therapy makes it easier to make informed decisions and recognise what’s part of the settling-in phase and what might need review. This guide covers the most common reactions, how long they tend to last, and when it’s a good idea to speak to your doctor.
Is bleeding normal on HRT?
Irregular spotting or light bleeding is common during the first three to six months of starting HRT and usually settles as your body adjusts.
- With sequential HRT, which mimics the menstrual cycle, a monthly ‘withdrawal’ bleed is expected at the end of each phase of progesterone.
- With continuous combined HRT, occasional spotting can occur in the first few months but typically eases over time [1].
If bleeding persists, becomes heavier, or occurs after a long time without periods, speak to your doctor as your regimen may need to be adjusted, or tests may be recommended to rule out other causes.
What are the most common HRT side effects?
Many women tolerate HRT well, but some may experience HRT side effects as their hormone levels begin to stabilise. These are usually mild and temporary.
Common HRT medication side effects include:
- Breast tenderness
- Headaches
- Nausea or digestive discomfort
- Bloating or stomach cramps
- Mood changes
- Light bleeding or spotting
- Skin sensitivity or rashes
These often resolve within a few weeks to three months as the body adapts, so it's recommended that if you are experiencing side effects, you carry on with treatment for at least 12 weeks to see if they improve with time [1].
Do different hormones cause different side effects?
Yes, the type of hormones you take can influence the side effects that you experience. Depending on your symptoms and medical history, you may be prescribed oestrogen alone, oestrogen combined with progesterone, or tibolone. If under a private specialist, it is also possible that you could be prescribed testosterone off-label.
Oestrogen HRT
Oestrogen is usually only prescribed on its own if you have had a hysterectomy, as unopposed oestrogen can increase the risk of endometrial hyperplasia and endometrial cancer [2]. More commonly, it is used in conjunction with progesterone to restore the body’s hormone balance to alleviate menopause symptoms.
Side effects of oestrogen include:
- Unexpected vaginal bleeding or spotting
- Nausea and vomiting
- Headache
- Mood changes
- Dry eyes
- Stomach cramps
- Bloating and fluid retention
- Weight changes
- Diarrhoea
- Breast tenderness
- Mild rash or itching
- Changes to libido
- Dizziness
- Leg cramps
- Thrush
- Hair loss [1][3]
Progesterone HRT
The type of progesterone used in HRT can vary, but a commonly prescribed option is Utrogestan, a body-identical form of micronised progesterone. It’s taken as a capsule and tends to be better tolerated than synthetic progestins, with a side effect profile that many women find easier to manage. This is because micronised progesterone is body-identical, it matches the structure of natural human progesterone, and tends to have fewer side effects than older synthetic progestins like medroxyprogesterone acetate or norethisterone, which are more likely to cause mood changes, bloating and breast tenderness.
Side effects of progesterone include:
- Spotting or irregular bleeding
- Tiredness
- Dizziness
- Headaches
- Acne or mild skin rashes
- Breast pain or tenderness
- Low mood or irritability
- Diarrhoea [1][4]
Tibolone
Tibolone is a type of HRT that contains synthetic hormones which the body breaks down to make substances that behave in a similar way to oestrogen, progesterone and testosterone [5].
Side effects of tibolone include:
- Stomach pain or pelvic pain
- Unusual hair growth
- Breast tenderness
- Vaginal irritation
- Vaginal bleeding [1][5]
Testosterone
Some women are prescribed testosterone as part of their HRT plan, especially to improve sexual desire when other causes have been ruled out [6]. HRT testosterone side effects are usually mild and reversible, and may include:
- Acne or oily skin
- Unwanted facial or body hair growth
- Weight gain [6]
Voice changes and scalp hair thinning can occur at high doses, but this is rare with the dosages prescribed as part of hormone replacement therapy [6]. In the UK, testosterone is not currently licensed for use in women. However, it may be prescribed off-label by menopause specialists in accordance with NICE guidance, especially for postmenopausal women experiencing low sexual desire after other causes have been ruled out.
HRT pills, patches and gels
Side effects of HRT pills may include more digestive symptoms (like nausea or bloating) because oral oestrogen is processed through the liver.
In contrast, transdermal HRT, such as patches, gels, sprays or creams, delivers hormones through the skin and tends to produce fewer systemic side effects. It also carries a lower risk of blood clots and stroke, making it a preferred option for many women, particularly those with cardiovascular risk factors.
Are there serious risks with HRT?
Most women will not experience serious complications from HRT. However, it’s important to be aware of the rare but potential risks.
Breast cancer
Combined HRT slightly increases the risk of breast cancer, particularly with long-term use. There are approximately five extra breast cancer cases in every 1000 women who take combined HRT for five years. However, the risk decreases once HRT is stopped. Oestrogen-only HRT (usually prescribed after hysterectomy) carries little to no increased risk [7].
Ovarian cancer
Both oestrogen-only and combined HRT may slightly increase ovarian cancer risk. The increase is small and reduces after stopping treatment [8].
Stroke and blood clots
HRT pills may increase the risk of stroke or blood clots, although the risk is still very low. Transdermal HRT (patches, gel, spray) does not carry this same risk, making it a safer option in many cases [7].
These long-term hormone replacement therapy side effects are rare, but worth discussing if you have personal or family risk factors.
How long do HRT side effects usually last?
Most HRT replacement side effects settle within a few weeks to three months. This is considered a normal adjustment period as your hormone levels reach a new balance.
If side effects continue beyond three months or become difficult to manage, speak to your doctor. In many instances, a small tweak in your dose, type of HRT, or method of delivery will help reduce the side effects.
Is there any way to reduce or avoid HRT side effects?
While it’s not always possible to avoid side effects of hormone replacement therapy, there are steps you can take to minimise them:
- Start with the lowest effective dose.
- Choose transdermal options (such as patches, gel, or spray) if you're sensitive to oral HRT.
- Stick to one formulation for at least three months before switching.
- Keep regular follow-ups with your doctor to fine-tune your treatment.
Personalised care is key; what works for one woman may not suit another.
Quick Tip: What to expect in the first 3 months
It’s completely normal to experience side effects when starting HRT as your hormone levels settle. These usually improve within 6 to 12 weeks. Keeping a symptom diary and having a review after three months can help make sure your treatment is working as well as possible.
When should I speak to my doctor about the side effects of HRT?
It’s worth booking an appointment to talk about your HRT regimen if:
- You’re experiencing persistent side effects after three months
- You notice heavy or unusual bleeding
- Your symptoms are affecting your quality of life
- You’re unsure whether your current HRT is still the right fit
Menopause care is not one-size-fits-all. There are many options available, and side effects should never be something you simply put up with.
Side effects of HRT therapy are often mild, temporary, and manageable, and for most women, the benefits of symptom relief and long-term health protection outweigh the risks.
Staying informed and having regular conversations with your doctor can help you get the best out of your treatment, whether you’re just starting HRT or considering a change.
At Voy, our menopause specialists are here to support you at every stage. You’ll have a dedicated care team that is there to help you decide on the right HRT regimen, manage side effects and address any lingering issues. To get started, book an appointment with Voy.
¹Side effects of hormone replacement therapy (HRT) - NHS (January 2023) https://www.nhs.uk/medicines/hormone-replacement-therapy-hrt/side-effects-of-hormone-replacement-therapy-hrt/
²Progestogens and endometrial protection (April 2023) https://thebms.org.uk/wp-content/uploads/2023/04/14-BMS-TfC-Progestogens-and-endometrial-protection-APR2023-A.pdf
³Oestrogen HRT. Hormone replacement therapy side effects - Patient (January 2025) https://patient.info/medicine/oestrogen-hrt-estradiol-conjugated-oestrogens
⁴Side effects of Utrogestan - NHS (January 2023) https://www.nhs.uk/medicines/hormone-replacement-therapy-hrt/utrogestan-micronised-progesterone/side-effects-of-utrogestan/
⁵About tibolone - NHS (January 2023) https://www.nhs.uk/medicines/hormone-replacement-therapy-hrt/tibolone/about-tibolone/
⁶Testosterone replacement in menopause (December 2022) https://thebms.org.uk/wp-content/uploads/2022/12/08-BMS-TfC-Testosterone-replacement-in-menopause-DEC2022-A.pdf
⁷Benefits and risks of hormone replacement therapy (HRT) - NHS (February 2023) https://www.nhs.uk/medicines/hormone-replacement-therapy-hrt/benefits-and-risks-of-hormone-replacement-therapy-hrt/
⁸Does hormone replacement therapy (HRT) increase the risk of cancer? (March 2023) https://www.cancerresearchuk.org/about-cancer/causes-of-cancer/hormones-and-cancer/does-hormone-replacement-therapy-increase-cancer-risk
