Experiences with
Anastrozole

Anastrozole is a medicine that works by lowering the level of oestrogen (a hormone) in your body.

It's mainly prescribed for women who have been through the menopause and have a type of cancer called hormone-dependent breast cancer.

Most people who take anastrozole will have had surgery, radiotherapy or sometimes chemotherapy to treat their breast cancer first. Anastrozole is an additional (adjuvant) treatment which helps stop the cancer coming back.

It can also be used:

to prevent breast cancer if you're high risk and have been through the menopause
to treat breast cancer in men
to treat breast cancer in younger women before the menopause

Anastrozole is available on prescription only. It comes as tablets.

Who can take anastrozole

Most adults aged 18 years old and over can take anastrozole.

Who may not be able to take anastrozole

Anastrozole is not suitable for some people. To make sure it's safe for you, tell your doctor before starting to take it if you:

have ever had an allergic reaction to anastrozole or any other medicine
still have periods
are pregnant, trying to get pregnant or breastfeeding
have severe kidney or liver disease
have been told you have fragile or brittle bones (osteoporosis)
have an allergy to lactose

Dosage

Anastrozole comes as 1mg tablets. The usual dose is 1 tablet, taken once a day.

Try to take your anastrozole at the same time each day, as this will make it easier to remember. You can choose a time that suits your routine.

How to take it

Swallow the tablet whole with a drink of water. Do not crush or chew it.

You can take anastrozole with or without food.

How long to take it for

You'll usually take anastrozole for 5 years. However, sometimes your doctor will advise if you need to take it for longer.

You might take just anastrozole for the whole of the 5-year course of treatment, or you might take another breast cancer medicine called tamoxifen first, for 2 to 3 years, and then change to anastrozole for the remaining time.

Anastrozole is sometimes used to treat cancer if you cannot have surgery, or to reduce the chances of the cancer coming back after surgery. In this case, your specialist will tell you how long to take it for.

Anastrozole can also be used to reduce the risk of getting breast cancer if you've been through the menopause and have a medium or high risk of breast cancer because of your family history. In this case you'll usually take it for 5 years.

If you forget to take it

If you forget to take your anastrozole, just skip the missed dose. Take your next dose at the usual time.

Do not take 2 doses to make up for a forgotten one.

If you forget doses often, it may help to set an alarm to remind you. You could also ask your pharmacist for advice on other ways to help you remember to take your medicine.

If you take too much

If you take too many anastrozole tablets, you may get symptoms like feeling sick, vomiting or diarrhoea.

you take more than your prescribed dose of anastrozole and feel unwell

Call 111 or get help from 111 online .

If you need to go to A&E, do not drive. Ask someone to drive you or call 999 and ask for an ambulance.

Bring the anastrozole packet or leaflet inside it, any remaining medicine, and any other medicines you take.

Common side effects

Anastrozole can cause symptoms similar to the menopause such as hot flushes, difficulty sleeping, tiredness and low mood, but these usually improve during the first months of taking it.

However, if the symptoms are severe or last longer than a few months, talk to your doctor or breast cancer nurse.

These common side effects of anastrozole happen in more than 1 in 100 people. There are things you can do to help cope with them:

Try cutting down on spicy food, caffeine, smoking and alcohol. It may help to keep the room cool and use a fan. Try spraying your face with cool water or sipping a cold drink.

Ask your doctor or breast cancer nurse to recommend a vaginal moisturiser for treating irritation or dryness.

Talk to your doctor if these symptoms first appear more than a few weeks after you start taking anastrozole.

Vaginal bleeding usually happens in the first few weeks after starting anastrozole. Talk to your doctor if it lasts longer than a few days.

Also talk to your doctor if you first get vaginal bleeding more than a few weeks after you start taking anastrozole.

Avoid caffeine (such as tea, coffee, cola, energy drinks and chocolate) in the afternoon and evening. Keep your bedroom dark and quiet, and try going to bed and getting up at a set time each day.

It may also help to stop watching TV, looking at your mobile phone or using other electronic devices (like tablets), at least 1 hour before bedtime.

Gentle exercise and eating healthily can help make you feel less tired. Try going to bed and getting up at a set time each day.

Do not drive, ride a bike or use tools or machinery if you feel very tired while taking anastrozole.

This will usually start to improve as your body gets used to the medicine. Speak to your doctor if it does not get better.

Stick to simple meals and do not eat rich or spicy food. It might help to take anastrozole after you've eaten.

If you're being sick, have small, frequent sips of water to avoid dehydration. Signs of dehydration include peeing less than usual or having dark strong-smelling pee.

Talk to your doctor if your symptoms do not improve or get worse.

It might help to take anastrozole after you've eaten.

Eat when you would usually expect to be hungry. If it helps, eat smaller meals throughout the day rather than big meals. Snack when you're hungry. Have nutritious snacks that are high in calories and protein, such as dried fruit and nuts.

Ask a pharmacist to recommend a suitable painkiller. If the pain does not go away ask your doctor for advice.

If you have a sudden attack of pain in a joint ask a doctor for advice urgently. Anastrozole can make your bones weaker and there is an increased risk of osteoporosis or bone injuries.

Ask your doctor for advice if you get this side effect.

Your doctor may suggest using a steroid cream or taking an antihistamine. You can buy these at a pharmacy without a prescription. Check with a pharmacist to see what type is suitable for you.

Some people find that their hair gets thinner when they start taking anastrozole. This is usually mild. Ask your breast cancer nurse for advice if this is bothering you.

It's difficult to know whether this is due to the medicine, dealing with menopause symptoms or dealing with being diagnosed with cancer.

Speak to your doctor or specialist nurse. They may recommend therapies, like cognitive behavioural therapy or mindfulness, or antidepressant medicines.

Talk to your doctor or a pharmacist if this advice on how to cope does not help and these side effects bother you or do not go away.

Serious side effects

Serious side effects are rare and happen in less than 1 in 100 people.

Call a doctor or call 111 now if:

your muscles feel weak, or the joints or tendons in your ankles, legs, shoulders or arms feel weak, painful or swollen
the whites of your eyes turn yellow, or your skin turns yellow although this may be less obvious on brown or black skin – this can be a sign of liver problems
you're feeling thirsty and peeing a lot, feeling sick and have lost your appetite – you may need a blood test to check your calcium levels
you get red or purple spots (if you have light skin) or dark spots (if you have brown or black skin), painful joints, stomach ache, or pain in your side (below your ribs), lower back or around your genitals – these can be signs of Henoch-Schönlein purpura, a condition causing inflammation of your blood vessels

you have sudden weakness or if you lose feeling in any part of your body, if your face drops on 1 side or you have difficulty speaking – these can be signs of a stroke
you have very sudden chest pain – this can be a sign of a heart attack

Meds - serious side effects A&E safety messaging

In rare cases, it's possible to have a serious allergic reaction (anaphylaxis) to anastrozole.

Meds New IA (H4) - serious allergic reaction

Anastrozole is generally safe to take for a long time. However, it can make your bones weaker and more likely to break (osteoporosis).

You may have bone density (DEXA) scans to check how strong your bones are, before you start taking anastrozole, 1 or 2 years into treatment, and again after you finish your treatment.

Your doctor may recommend a type of medicine called a bisphosphonate to help make your bones stronger. They can also give you advice on exercise and diet to help keep your bones strong.

Anastrozole can also increase your cholesterol levels. Your doctor will monitor this during your regular check-ups and recommend treatment if you need it.

Other side effects

These are not all the side effects of anastrozole. For a full list, see the leaflet inside your medicines packet.

Anastrozole and pregnancy

Anastrozole is not recommended when pregnant.

This is because it affects hormone levels in you and your baby. There's not enough information available to say if it's safe.

Talk to your doctor straight away if there's any chance that you could be pregnant.

Anastrozole and breastfeeding

Anastrozole is not recommended while you're breastfeeding.

There's no information about how much anastrozole passes into breast milk but it's likely to be a fairly high amount compared to most other medicines.

Anastrozole affects hormones, which may affect how your baby develops.

Anastrozole and fertility

Anastrozole is generally only given to you if you have gone through the menopause.

However, some people find that they start having periods again after taking anastrozole. If this happens to you, it's important to use reliable contraception.

Talk to your doctor if your periods start again, or if there's any chance you could be pregnant.

Meds New IA (H2) - Pregnancy non-urgent care card

Cautions with other medicines

There are very few medicines that affect the way anastrozole works in the body.

However, do not take hormone replacement therapy (HRT) or any other medicines that relieve menopause symptoms. These may contain ingredients similar to the hormone oestrogen and could stop anastrozole working as well as it should.

Mixing anastrozole with herbal remedies and supplements

Do not take any herbal remedies or supplements for menopause symptoms while taking anastrozole. These may stop anastrozole working as well as it should.

There's not enough information to say that other complementary medicines, herbal remedies and supplements are safe to take with anastrozole. They're not tested in the same way as pharmacy and prescription medicines. They're generally not tested for the effect they have on other medicines.

Meds New IA (H2) - Cautions with other medicines alert