Like all medicines, oestrogen tablets, patches, gel and spray 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.
If you're also taking a progestogen medicine, some side effects may be caused by the progestogen. Check the leaflets that come with both your medicines.
Common side effects
These common side effects of oestrogen tablets, patches, gel and spray happen in more than 1 in 100 people. There are things you can do to help cope with them:
Headaches
Headaches usually only last for a few days after you start taking oestrogen 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 pain or tenderness
This usually improves after a few weeks as your body gets used to the medicine. Speak to a doctor if it bothers you or does not go away.
If you notice a lump or changes in your breasts after a few months of taking oestrogen, contact your doctor for advice.
Unexpected vaginal bleeding or spotting
Unless you've had a hysterectomy to remove your womb, vaginal bleeding or spotting is common for the first 3 to 6 months after starting HRT, but usually settles down.
If you get heavy bleeding or unexpected bleeding after you've been taking HRT for 6 months, talk to your doctor.
Talk to your doctor if you've had a hysterectomy and you get any vaginal bleeding.
Feeling sick (nausea)
If you're taking oestrogen tablets, try taking them with food. Stick to simple meals and do not eat rich or spicy foods.
This side effect should wear off after a few days as your body gets used to the medicine. If it lasts more than a week, speak to your doctor. You may need to change your dose or switch to a different type of HRT.
Mood changes, including low mood or depression
This may last for the first few months as your body gets used to the medicine.
If it lasts longer than this or becomes too difficult to cope with, speak to your doctor. You may need to change your dose or switch to a different type of HRT.
Leg cramps
Leg cramps usually only last for the first few weeks after you start taking oestrogen. Stretching your calf muscles regularly and gentle exercise may help prevent it.
If you keep getting leg cramps after the first few months of taking oestrogen, talk to your doctor as you may need a different treatment.
Mild rash or itching
If this covers a large area of skin it will usually only last for about a week as your body gets used to the medicine.
It may help to take an antihistamine which you can buy from a pharmacy. Check with the pharmacist to see what type is suitable for you.
If it does not go away after about a week, talk to your doctor, as you may need a different treatment.
If you're using patches, gel or spray and the rash or itchiness is only affecting the area where you're putting the oestrogen, talk to your doctor as you may need a different treatment.
Diarrhoea
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. 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.
Hair loss
If you have hair loss this may not always be caused by taking oestrogen, as it's sometimes a symptom of the menopause. If it worries you, speak 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 oestrogen 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 a GP 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 oestrogen 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: Call 999 or go to A&E 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 oestrogen.
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 oestrogen tablets, patches, gel and spray. For a full list see the leaflet inside your medicines packet.
You can report any suspected side effect using the Yellow Card safety scheme.