Anastrozole for breast cancer

  • Take one tablet each day.
  • You can take the tablets before or after meals.
Type of medicine An aromatase inhibitor hormone antagonist
Used for Treatment of some types of breast cancer in women who have had their menopause
Also called Arimidex®
Available as Tablets

Some breast cancers need the hormone oestrogen to grow. In women who have had their menopause, the main source of oestrogen is through the change of the sex hormone androgen into oestrogen. Anastrozole works by preventing this change by blocking an enzyme in your body called 'aromatase'. This reduces the amount of oestrogen in your body, which slows the growth of the cancer cells.

Some medicines are not suitable for people with certain conditions, and sometimes a medicine may only be used if extra care is taken. For these reasons, before you start taking anastrozole it is important that your doctor or pharmacist knows:

  • If you have not gone through the menopause.
  • If you have liver or kidney problems.
  • If you have osteoporosis or any other condition that affects the strength of your bones.
  • If you are taking other medicines, including those available to buy without a prescription, herbal and complementary medicines. It is particularly important that your doctor knows if you are taking tamoxifen or any oestrogen-containing medicines, such as hormone replacement therapy.
  • If you have ever had an allergic reaction to this or to any other medicine.
  • Before starting this treatment, read the manufacturer's printed information leaflet from inside the pack. The leaflet will give you more information about anastrozole. It will also list the unwanted side-effects from taking it.
  • Take one 1 mg tablet of anastrozole each day, exactly as your doctor has told you. Your dose will also be on the label of the tablet pack.
  • You may take anastrozole at whatever time of day you find easiest to remember, but try to take your doses at the same time each day. This will help you to avoid missing any doses.
  • You can take the tablets before, during or after your meals.
  • If you forget to take a dose, take it as soon as you remember. If you do not remember until the following day, skip the missed dose. Do not take two doses together to make up for a forgotten dose.
  • Try to keep your regular appointments with your doctor or clinic. This is so your doctor can check on your progress. Anastrozole lowers the levels of female hormones in your body, which can reduce the strength of your bones. You may need to have bone density tests before and during your treatment to check for this.
  • Anastrozole is a long-term treatment and you may need to take it for several years.
  • If you are having an operation or dental treatment, tell the person carrying out the treatment that you are taking anastrozole.
  • If you buy any medicines, check with a pharmacist that they are safe to take with your other medicines.

Along with their useful effects, most medicines can cause unwanted side-effects although not everyone experiences them. These usually improve as your body adjusts to the new medicine, but speak with your doctor or pharmacist if any of the following side-effects continue or become troublesome.

Common anastrozole side-effects What can I do if I experience this?
Hot flushes Try to keep cool by wearing light, airy clothes
Feeling or being sick, loss of appetite Try eating smaller meals, but more often. Stick to simple foods and avoid rich or spicy foods
Feeling tired or sleepy If this happens, do not drive or use tools or machines
Headache This is usually mild and does not last long. Ask your pharmacist to recommend a suitable painkiller
Diarrhoea Drink plenty of water to replace the lost fluids
Skin rash, joint aches and pains, vaginal dryness, hair thinning, carpal tunnel syndrome If any of these become troublesome, speak with your doctor

Important: if you experience any of the following less common but more serious adverse effects, contact your doctor for advice:

  • A severe skin rash with blisters.
  • Vaginal bleeding.

If you experience any other symptoms which you think may be due to this medicine, discuss them with your doctor or pharmacist.

  • Keep all medicines out of the reach and sight of children.
  • Store in a cool, dry place, away from direct heat and light.
  • Never take more than the prescribed dose. If you suspect that someone has taken an overdose of this medicine go to the accident and emergency department of your local hospital. Take the container with you, even if it is empty.
  • This medicine is for you. Never give it to other people even if their condition appears to be the same as yours.
  • Never keep out-of-date or unwanted medicines. Take them to your local pharmacy which will dispose of them for you.
  • If you have any questions about this medicine ask your pharmacist.

Further reading & references

  • British National Formulary; 62nd Edition (Sep 2011) British Medical Association and Royal Pharmaceutical Society of Great Britain, London
  • Manufacturer's PIL, Arimidex®; Manufacturer's PIL, Arimidex®, AstraZeneca UK Limited, electronic Medicines Compendium. Dated June 2011.
  • Manufacturer's PIL, Nastrosa® 1 mg film-coated tablets; Manufacturer's PIL, Nastrosa® 1 mg film-coated tablets, Discovery Pharmaceuticals Ltd, electronic Medicines Compendium. Dated December 2010.

Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. EMIS has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.

Original Author:
Helen Allen
Current Version:
Peer Reviewer:
Prof Cathy Jackson
Document ID:
3784 (v25)
Last Checked:
Next Review:
The Information Standard - certified member