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Zoledronic acid for primary breast cancer

Zoledronic acid reduces the risk of breast cancer spreading to the bones and other parts of the body. Read more about how it's given and its side effects.

1. What is zoledronic acid?

Zoledronic acid is a drug given to reduce the risk of breast cancer coming back and spreading to the bones and other parts of the body.

You may hear it called by its brand name Zometa.

Zoledronic acid belongs to a group of drugs called bisphosphonates.

You may hear bisphosphonates called bone-hardening or bone-strengthening treatment.

2. How does zoledronic acid work?

Bisphosphonates slow down or prevent bone damage.

In all our bodies, whether or not we have cancer, bone tissue breaks down over time and is replaced with new bone tissue. This is a natural process called bone remodelling.

Cancer cells seem to be drawn to areas where bone remodelling is taking place, so secondary breast cancer commonly affects the bones (as well as the lungs, liver and brain).

Bisphosphonates like zoledronic acid work by being absorbed in areas of the body where there is a lot of bone remodelling.

This interferes with the remodelling process so may reduce the risk of breast cancer spreading to the bones and elsewhere in the body.

3. When is zoledronic acid prescribed?

Primary breast cancer

Zoledronic acid is suitable for some women with . It is given to reduce the risk of breast cancer coming back.

Zoledronic acid is prescribed for women who have been through the menopause (post-menopausal women). It can be used regardless of whether the menopause happened naturally or because of breast cancer treatment.

The benefits of using zoledronic acid before the menopause are less clear.

You may be offered zoledronic acid if you are post-menopausal and have had treatment for invasive breast cancer that has spread to the under the arm.

Zoledronic acid may also be considered if your cancer has not spread to the lymph nodes but other factors increase its risk of returning.

Zoledronic acid is usually started within 3 months of final surgery.

If you are having after surgery, you’ll usually start taking zoledronic acid within 2 months of completing chemotherapy.

Other uses of zoledronic acid

Zoledronic acid is also prescribed:

4. How is zoledronic acid given?

Zoledronic acid is given as a drip into a vein in your hand or arm (intravenously).

If you had chemotherapy and you have another way of accessing your veins, such as a PICC line or central line, this can be used to give you the drug.

The infusion is usually given in the chemotherapy department of your hospital and takes about 15 minutes.

You may be given an infusion of zoledronic acid every 6 months for 3 years or every 3 months for 2 years.

5. Side effects of zoledronic acid

Like any drug, zoledronic acid can cause side effects. Everyone reacts differently to drugs and some people have more side effects than others. Side effects can usually be managed and those described here will not affect everyone.

If you’re worried about any side effects, regardless of whether they are listed here, talk to your GP or treatment team.

Common side effects

Flu-like symptoms

Zoledronic acid can cause flu-like symptoms such as joint and muscle pain.

Other flu-like effects include fatigue, shivering and fever. These can last for a few days.

Your treatment team can advise you about taking mild pain relief to help.

Feeling sick (nausea) or being sick (vomiting)

This is usually mild. Your treatment team can prescribe anti-sickness drugs to relieve it.


You may have a headache lasting for a couple of hours to a couple of days after your infusion. Let your treatment team know if you get headaches as they can advise you about taking mild pain relief.

Red or sore eyes

Your eyes may be sore or red for a few days after your treatment. Your treatment team can prescribe eyedrops to relieve this.


Having too few red blood cells is called anaemia.

If you feel particularly tired, breathless or dizzy, let your treatment team know.

You’ll have regular blood tests throughout your treatment.

Less common side effects


This is usually mild. Your treatment team can prescribe anti-diarrhoea medication to help control this. 

Contact your treatment team if you have 4 or more episodes of diarrhoea within a 24-hour period.

Drink plenty of fluids to avoid getting dehydrated. 

Low calcium levels in the blood

Zoledronic acid can cause calcium levels in the blood to drop too low. This is called hypocalcaemia. You’ll have regular blood tests to check the calcium levels.

Early symptoms of hypocalcaemia include tingling around the mouth and lips and in the hands and feet. Let your treatment team know if you experience any of these.

Your treatment team may recommend calcium and vitamin D supplements.

Allergic reaction

Zoledronic acid can sometimes cause an allergic reaction. Let your treatment team know straight away if you become breathless or start to develop an itchy rash.


Zoledronic acid can cause some of the jaw bone to lose its blood supply and die. This is called osteonecrosis of the jaw (ONJ). It’s a rare but serious side effect of zoledronic acid.

Your treatment team will recommend you see a dentist before starting zoledronic acid. If you need any dental work, it’s important to speak to your treatment team, as any problems with your teeth or gums must be completely healed before starting treatment.

If you need to have a dental procedure, such as having a tooth removed, you’ll need to wait at least 4 weeks afterwards before starting or restarting zoledronic acid.

If you don’t have a dentist or you are having difficulty registering with one, let your treatment team know.

When you are having zoledronic acid, you may be given a dental alert card to show a dentist if you develop any symptoms of ONJ. These include:

  • Lasting jaw pain
  • Loose teeth
  • Swelling, redness or ulcers on the gums

Let your treatment team and dentist know straight away if you have any of these symptoms.

ONJ is hard to treat so trying to prevent it is very important. Good dental hygiene can help reduce the risk of developing it. This includes brushing your teeth and flossing, making sure dentures fit well and having regular dental check-ups.

There is also evidence that people who smoke are more at risk of developing ONJ. Speak to your treatment team or GP if you need support with stopping smoking.

It’s not clear how long the risk of ONJ continues for once treatment is completed.

In rare cases osteonecrosis can affect the ear. If you have any ear pain, discharge from your ear or an ear infection while having zoledronic acid let your treatment team know.


Although it’s rare, zoledronic acid can cause the large bone in the upper leg (femur) to fracture. It’s not fully understood why this happens.

If you have lasting pain in your thigh, hip or groin, let your treatment team know.

Effects on the kidneys

Zoledronic acid can affect the way the kidneys work.

You will have blood tests before you start treatment and throughout treatment to monitor this.

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Quality assurance

This information was published in November 2023. We will revise it in November 2025.

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