What is clodronate?

Clodronate belongs to a group of drugs called bisphosphonates. It can be used to treat:

  • high levels of calcium in the blood caused by cancer that has spread to the bones
  • bone weakness or pain caused by myeloma or breast cancer that has spread to the bones.

Cancer that has spread to the bones is called secondary bone cancer. It happens when cells from the original (primary) cancer spread to form a new tumour (secondary cancer or metastasis) in the bone.

Myeloma is a cancer of a type of blood cell called plasma cells. The abnormal plasma cells build up inside bones causing pain and weakness.

Clodronate can be given with other cancer treatments.

The effect of cancer on the bones

In normal bones, two types of cell work together to keep your bones healthy. They are:

  • osteoclasts, which destroy old bone
  • osteoblasts, which build new bone.

Myeloma and some secondary bone cancers make chemicals that cause osteoclasts to work harder. This means that more bone is destroyed than rebuilt. The affected bone becomes weak and painful and can break more easily.

Bones contain calcium, which gives them strength. A bone affected by secondary cancer or myeloma may lose calcium into the blood. A raised level of calcium in the blood is called hypercalcaemia. This may cause you to have symptoms including:

  • feeling sick (nausea)
  • vomiting
  • tiredness
  • irritability
  • confusion.

How clodronate works

Clodronate reduces the activity of osteoclasts. This can help reduce pain and strengthen the bone.

Clodronate also reduces the amount of calcium that is lost from the bones. This helps calcium levels in the blood return to normal.

How clodronate is given

You usually take clodronate by mouth as capsules or tablets. You usually take them once or twice a day.

Clodronate should be swallowed whole with a full glass of plain tap water. Never take it with milk because this reduces the amount of clodronate your body can absorb.

You need to drink plenty of fluids, such as water, while you are taking clodronate treatment.

Always take clodronate tablets exactly as explained. This is important to make sure they work as well as possible for you. Check with your doctor or pharmacist if you are not sure.

If you take clodronate once a day

Take your tablets in the morning on an empty stomach, with a full glass of plain tap water. After taking clodronate, do not eat, drink anything (other than tap water) or take any other medicines by mouth for 1 hour.

If you take clodronate twice a day

Take the first dose as recommended above. Take the second dose between meals, at least 2 hours after and 1 hour before eating, drinking anything (other than tap water) or taking any other medicines by mouth.

It is important to follow these instructions or your body will not absorb the drug properly.

How long clodronate is given for

How long clodronate is given for depends on why you are having the treatment:

  • If you are having clodronate to lower calcium levels in your blood, you may have tablets or capsules to maintain your calcium at a normal level.
  • If the calcium level in your blood is very high, you may have a single dose of another bisphosphonate into a vein to bring it down faster.
  • If you are having clodronate to reduce pain or strengthen your bones, your doctor will talk to you about how long you may need to take it for. You may need to take it for as long as it seems to be working.

About side effects

Serious and life-threatening side effects

Some cancer treatments can cause severe side effects. Rarely, these may be life-threatening. Your cancer doctor or nurse can explain the risk of these side effects to you.

More information about this drug

We are not able to list every side effect for this treatment here, particularly the rarer ones. For more detailed information you can visit the electronic Medicines Compendium (eMC).

Common side effects

Some people have very few side effects while others may have more. The side effects described below do not affect everyone taking clodronate. If you are taking other drugs, you may have some side effects that we do not list here.

We explain the most common side effects here, but have not included those that are rare and therefore unlikely to affect you. If you notice any effects that are not listed below, tell your cancer doctor or specialist nurse.

Feeling sick (nausea)

You may feel sick or be sick (vomit) during treatment for clodronate. This is usually mild. Your doctor can prescribe anti-sickness drugs to help.

Take the drugs exactly as your nurse or pharmacist tells you to. It is easier to prevent sickness than treat it after it has started.

Abdominal (tummy) pain

Tell your doctor if you have abdominal (tummy) pain that is severe, or continues.


Tell your doctor if you have diarrhoea or constipation. They can give you medicine to help with this. Remember to drink at least 2 litres (3½ pints) of fluids a day.

Less common side effects

Numbness or tingling

You may notice numbness or tingling around the mouth or in the fingers and toes. This may be caused by low levels of calcium in your blood. You will have regular blood tests to check your calcium levels. Contact your doctor straight away if you have these symptoms.

Your doctor may ask you to take calcium and vitamin D supplements, unless you are having this treatment to lower the levels of calcium in your blood.

Effect on the kidneys

Clodronate can affect how your kidneys work. Drinking plenty of fluids will help your kidneys work well. Your doctor will check how well your kidneys are working with regular blood tests.

Tell your doctor if:

  • you feel generally unwell
  • have any swelling of your face, arms, legs or tummy
  • you notice a change in how often you pass urine (pee).

Effects on the liver

Clodronate can affect the liver. This is usually mild and does not cause any symptoms. It goes back to normal after treatment. You will have blood tests to check how well your liver is working.

Pain in the thigh, hip or groin

Rarely, people having this treatment develop a break (fracture) in their thigh bone without any obvious cause. Sometimes both thigh bones are affected.

If you have any thigh, hip or groin pain, tell your doctor and mention that you are taking bisphosphonates. They can arrange tests to check the thigh bones for any signs of weakness or fracture.

Jaw problems

Rarely, this treatment can affect the jaw bone. Healthy bone in the jaw becomes damaged and dies. This is called osteonecrosis of the jaw (ONJ). It can cause:

  • pain
  • loosening of the teeth
  • problems with the way the gums heal.

The risk of jaw problems is higher after some types of dental treatment. It is also higher in people who have gum disease or dentures that do not fit well.

It is important to avoid having any dental treatment that could affect your jaw bone when you are having bisphosphonates. This includes having a tooth or root removed or dental implants put in. It is fine to have fillings, gum treatments or a scale and polish.

To reduce your risk of developing jaw problems, your doctor will advise you to:

  • have a full dental check-up before starting treatment
  • look after your teeth and gums during treatment (ask your dentist for advice)
  • tell your dentist you are taking a bisphosphonate before having any dental treatment.

Tell your doctor and dentist straight away if you develop:

  • pain
  • swelling or redness in your gums
  • numbness or heaviness in your jaw
  • loose teeth.

Ear problems

Very rarely, bones in the outer ear may be affected by this treatment. Always tell your doctor if you have any:

  • ear pain
  • discharge from your ear
  • ear infections.

You should also tell them know if you notice any other changes in your ears or hearing.

Allergic reaction

Rarely, clodronate can cause an allergic reaction. If you suddenly feel breathless or develop an itchy rash, seek medical advice straight away.

Other information

It's important to let your doctor know straight away if you feel unwell or have any severe side effects, even if they are not mentioned above.

Going into hospital

If you are admitted to hospital for a reason not related to the cancer, it is important to tell the doctors and nurses that you are having treatment with bisphosphonates. You should tell them the name of your cancer doctor so they can ask them for advice.

Emergency contacts

It is a good idea to find out who you should contact if you have any problems or difficult side effects when you are at home. Your cancer doctor or specialist nurse can give you advice about this.

Other medicines

Some medicines can increase the side effects of this treatment or make it work less well. This includes medicines and supplements you can buy in a shop or chemist. Tell your cancer doctor about any medicines you are taking, including over-the-counter drugs, complementary therapies and herbal drugs.

Pregnancy and breastfeeding

If you are pregnant, think you may be pregnant, or are planning to have a baby, ask your doctor or pharmacist for advice before taking this medicine.

Women are also advised not to breastfeed when taking this treatment. This is because the medicine may be passed to the baby through the breast milk.

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