Letrazole

Letrozole can be taken by adults only (aged 18 years and over). Letrozole is not suitable for some people. Tell your doctor before starting on this medicine if you:

• have had an allergic reaction to letrozole or any other medicines in the past
• still have periods
• are pregnant, trying to get pregnant or breastfeeding
• have serious kidney or liver disease
• have been told you have fragile or brittle bones (osteoporosis)

Pregnancy and breastfeeding

Letrozole is not recommended when pregnant or breastfeeding. This is because it can harm your baby. Talk to your doctor urgently if there is any chance that you could be pregnant.

Letrozole comes as 2.5mg tablets. The usual dose is 1 tablet, taken once a day. Try to take your letrozole at the same time each day. You can choose a time that suits your everyday routine. This will make it easier to remember to take your medicine.

Swallow the tablet whole with a drink of water. Do not crush or chew it. You can take letrozole with or without food.

What if I forget to take it?

If you forget a dose take it as soon as you remember, unless your next dose is due in 2 or 3 hours. In this case skip the missed dose and take your next one at the usual time. Do not take a double dose to make up for a forgotten dose.

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

What if I take too much?

If you take too many letrozole tablets by accident, you may get symptoms like feeling sick, blurred vision or a fast heartbeat.

Like all medicines, Letrozole can cause side effects, although not everyone gets them.

Common side effects

These common side effects happen in more than 1 in 100 people.

Menopause symptoms usually improve during the first few months of taking letrozole. Talk to your doctor or a pharmacist if these side effects bother you or do not go away:

• hot flushes and sweating
• dry or itchy vagina, bleeding from your vagina
• difficulty sleeping
• feeling very tired
• feeling or being sick, loss of appetite
• mild aches in your muscles and bones
• numb or tingling hands
• changes to your skin, including a mild rash
• hair loss
• low mood or depression

Letrozole may also affect your blood pressure, cholesterol and bone density. Your doctor will monitor this carefully and can recommend additional treatment if needed.

Serious side effects

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

• you get a skin rash that may include itchy, red, swollen, blistered or peeling skin
• you are wheezing
• you get tightness in the chest or throat
• you have trouble breathing or talking
• your mouth, face, lips, tongue or throat start swelling

How to cope with side effects of letrozole

Menopause symptoms such as hot flushes, difficulty sleeping, tiredness and low mood usually improve during the first months of taking letrozole. However, if they are severe or last longer than a few months, talk to your doctor 

What to do about:

• hot flushes and sweating – 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.

• dry or itchy vagina, bleeding from your vagina – ask your doctor to recommend a vaginal moisturiser for treating irritation or dryness. Vaginal bleeding usually happens in the first few weeks after starting letrozole. Talk to your doctor if it lasts longer than a few days. Also talk to your doctor if these symptoms first appear more than a few weeks after you start taking letrozole.

• difficulty sleeping – avoid caffeine (tea, coffee, cola 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. Stop watching TV and using electronic devices like mobiles or tablets at least 1 hour before bedtime.

• feeling very tired – 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 operate machinery if you feel very tired while taking letrozole. 

• feeling or being sick, loss of appetite – it might help to take letrozole after you have eaten. Choose foods you normally enjoy but avoid rich or spicy food. Try eating smaller meals but more often. If you are being sick, have small frequent sips of water to avoid dehydration. Talk to your doctor if your symptoms do not improve or get worse.

• mild aches in your muscles or bones – ask a pharmacist to recommend a suitable painkiller. If the pain lasts more than a week, ask your doctor for advice. If you have a sudden attack of pain in a joint, ask a doctor for advice urgently.

• numb or tingling hands – stop taking the medicine and ask your doctor for advice

• changes to your skin, including a rash – it may help to take an antihistamine. You can buy these at a pharmacy without a prescription. Check with a pharmacist to see what is suitable for you.
• hair loss – some people find their hair gets thinner when they start taking letrozole. This is usually mild. Ask your breast cancer nurse for advice if this is bothering you.
• low mood or depression – it is difficult to know whether this is due to the medicine, dealing with menopausal symptoms or dealing with a diagnosis of cancer. Speak to your doctor or specialist nurse. They may recommend therapies, like cognitive therapy or mindfulness, or antidepressant medicines.

Cautions with other medicines

There are very few medicines that interfere with the way letrozole works in the body. However, do not take any medicines like hormone replacement therapy that relieve menopausal symptoms. These may contain ingredients similar to the hormone oestrogen and could stop letrozole working as well as it should in treating your cancer.

Mixing letrozole with herbal remedies and supplements

Do not take any herbal remedies or supplements for menopausal symptoms while taking letrozole. These can stop letrozole working as well as it should.

How does Letrozole work?

Letrozole belongs to a group of medicines called aromatase inhibitors. Aromatase inhibitor medicines are used to treat certain types of breast cancer, where the cancer cells need oestrogen (a hormone) in order to grow.

After the menopause your ovaries stop producing oestrogen. Instead, your body makes oestrogen from an enzyme called aromatase. Aromatase inhibitors reduce the amount of aromatase in your body and this in turn stops your body producing oestrogen. This helps prevent cancer cells growing, as they no longer have anything to feed on.

What are the benefits of taking Letrozole?

Letrozole helps stop your breast cancer coming back. By taking this medicine for 5 years (or sometimes up to 10 years), you have a better chance of being alive 15 years after your breast cancer was first diagnosed.

How long does it take to work?

Letrozole will immediately start to reduce the amount of oestrogen in your body. However, it takes several weeks or months for the medicine to work fully.

During this time, you are likely to have menopause symptoms as your body gets used to having less oestrogen. These symptoms will gradually improve as your body adjusts to the medicine.

How long will I take it for?

Most people who take letrozole will have had surgery, radiotherapy or sometimes chemotherapy to treat their breast cancer first.

In this case, surgery, radiotherapy or chemotherapy is the first (“primary”) treatment and letrozole is an additional (“adjuvant”) therapy. Adjuvant therapy helps stop the cancer coming back.

Is it safe to take for a long time?

Letrozole is generally safe to take long term, however, your specialist team will monitor your health carefully.

This is because letrozole reduces levels of oestrogen that your body needs for strong and healthy bones. If you take letrozole for a long time your bones can become weaker (osteoporosis) and more likely to break.

Can I stop taking it?

If you want to stop taking it for any reason, your doctor will be able to discuss alternatives for treating your breast cancer or preventing it coming back.

Sometimes people are given a short break from letrozole. This can help if you are getting side effects such as joint pain.

Are there other medicines like Letrozole?

Medicines such as tamoxifen, anastrazole and exemestane work in a similar way to letrozole. These medicines lower your oestrogen levels and can cause similar side effects.

However, medicines affect people in different ways. If you are bothered by side effects from taking letrozole, talk to your doctor.

Can I drink alcohol with it?

There is no evidence that drinking alcohol causes any problems when taking letrozole. Some people taking letrozole may get hot flushes or redness when they drink alcohol. In this case, avoiding alcohol may help.

Is there any food or drink I need to avoid?

Most people can eat and drink normally when taking letrozole. Although some people may get hot flushes or redness when they drink alcohol.

Some people find letrozole affects their appetite. If you lose your appetite, try to make sure you have a balanced diet by eating smaller meals and more often

Will it affect my contraception or fertility?

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

However, some people find they start having periods again after taking letrozole. If this happens to you, it is important to use reliable contraception.

Can I drive or ride a bike?

Some people feel extremely tired when taking letrozole.

If you feel tired or dizzy, or if you get blurred vision, do not drive, cycle or operate machinery until you feel okay again.