Like all medicines, continuous combined HRT can cause side effects, but it's common to have no side effects or only minor ones.
Side effects often improve as your body gets used to the medicine.
Common side effects
There are things you can do to help cope with these common side effects of continuous combined HRT:
Headache
Headaches usually only last for a few days after you start treatment as your body gets used to the medicine. Try taking a painkiller such as ibuprofen or paracetamol.
If headaches last longer than a week or are severe, speak to your doctor. You may need to change your dose or switch to a different type of HRT.
Breast tenderness or pain
This usually improves after 4 to 6 weeks as your body gets used to the medicine. If it lasts for longer than this or becomes too painful, speak to your doctor. Your doctor may suggest that you try a different dose or change to a different type of HRT.
If after a few months of taking HRT you notice a lump or changes in your breasts, contact your doctor for advice.
Unexpected vaginal bleeding or spotting
Irregular bleeding is common for the first few months after starting continuous combined HRT.
If you get heavy bleeding or unexpected bleeding after you've been taking it for 6 months, talk to your doctor.
Feeling sick (nausea)
Take your HRT tablets or capsules with food. Try to stick to simple foods until your body gets used to the medicine.
Feeling sick should wear off after a few days as your body gets used to the medicine. If it lasts for more than a week, speak to your doctor as you may need to try a different dose or change to a different type of HRT.
Mood changes
This may last for the first few months after you start treatment as your body gets used to the medicine. Speak to your doctor if it lasts for longer than this. You may need to try a different dose or change to a different type of HRT.
Muscle cramps
This should only last for the first few weeks after you start treatment. Stretching and gentle exercise may help prevent leg cramps. If it keeps happening after the first few months, talk to your doctor as you may need a different treatment.
Diarrhoea
This is more likely to happen with HRT tablets or capsules, not patches.
Drink lots of fluids, such as water or squash, to avoid dehydration. Signs of dehydration include peeing less than usual or having dark, strong-smelling pee.
If the diarrhoea lasts more than a week, speak to your doctor as you may need to try reducing your dose or changing to a different type of HRT. Do not take any other medicines to treat diarrhoea without speaking to a pharmacist or doctor.
Mild rash or itchy skin
If you are using patches, and the rash or itchiness is only affecting the area where you put on the patch, talk to your doctor as you may need a different treatment.
Itching or hives
If this affects a large area of skin, talk to your doctor.
Speak to a pharmacist or doctor if the advice on how to cope does not help and a side effect is still bothering you or does not go away.
Serious side effects
Serious side effects from continuous combined HRT are rare.
Call a doctor or call 111 for advice now if you have pain, redness or swelling in one of your legs, usually in your calf – this could be a sign of deep vein thrombosis (DVT).
Speak to your doctor if you have:
- a lump or changes in your breasts, especially dimpling of the skin, changes in the nipple or any lumps you can see or feel – this could be a sign of breast cancer
- any changes in vaginal bleeding after you have been taking HRT for more than a few months – this could be a sign of womb cancer
It's important to attend your breast screening (mammogram) appointments while you're taking HRT.
Immediate action required: Go to A&E or call 999 now if:
- you have pain in your chest and breathlessness – this could be a sign of a blood clot in your lungs (pulmonary embolism) or heart problems
- you have difficulty speaking or moving your arm or leg, or your face has dropped on one side – this could be a sign of a stroke
Serious allergic reaction
In rare cases, it's possible to have a serious allergic reaction (anaphylaxis) to continuous combined HRT.
Immediate action required: Call 999 now if:
- your lips, mouth, throat or tongue suddenly become swollen
- you're breathing very fast or struggling to breathe (you may become very wheezy or feel like you're choking or gasping for air)
- your throat feels tight or you're struggling to swallow
- your skin, tongue or lips turn blue, grey or pale (if you have black or brown skin, this may be easier to see on the palms of your hands or soles of your feet)
- you suddenly become very confused, drowsy or dizzy
- someone faints and cannot be woken up
- a child is limp, floppy or not responding like they normally do (their head may fall to the side, backwards or forwards, or they may find it difficult to lift their head or focus on your face)
You or the person who's unwell may also have a rash that's swollen, raised, itchy, blistered or peeling.
These can be signs of a serious allergic reaction and may need immediate treatment in hospital.
Other side effects
These are not all the side effects of continuous combined HRT. For a full list see the leaflet inside your medicines packet.
You can report any suspected side effect using the Yellow Card safety scheme.