Sodium clodronate (Clasteon, Loron)

Sodium clodronate is a type of bisphosphonate Open a glossary item. You might have it as a treatment for cancers that affect the bones such as myeloma and secondary breast cancer.

What is sodium clodronate?

Sodium clodronate is a type of bisphosphonate. You might have it as a treatment for a number of cancers that affect the bones such as myeloma Open a glossary item and secondary breast cancer Open a glossary item.

You may have sodium clodronate for any of the following reasons:

  • to treat high blood calcium (hypercalcaemia)
  • to strengthen weak areas of bone (osteolytic lesions)
  • to reduce bone pain due to cancers that have spread to the bone
  • to maintain calcium levels in the body after having treatment with another bisphosphonate drug

How does sodium clodronate work?

Cancer that spreads to the bones encourages the breakdown of bone. This weakens the bones, making them more likely to break (fracture). It can also cause pain and releases calcium from the bone cells into the blood.

Sodium clodronate works by slowing down the breakdown of bone and lowering the amount of calcium lost from the bones. It does this by attaching itself to the bone cells (osteoclasts Open a glossary item) to slow down the activity of the osteoclasts. 

How do you have sodium clodronate?

You take sodium clodronate as capsules or tablets once a day. You take them in the morning, on an empty stomach with water. You should wait at least 1 hour after you take them before you have a meal or other medicines.

Other foods, especially milk, can stop sodium clodronate being absorbed if they are taken closely together. 

Taking your tablets and capsules

You must take tablets and capsules according to the instructions your doctor or pharmacist gives you.

Whether you have a full or empty stomach can affect how much of a drug gets into your bloodstream.

You should take the right dose, not more or less.

Talk to your healthcare team before you stop taking or miss a dose of a cancer drug.

How often do you have sodium clodronate?

You usually take sodium clodronate every day. How long you take them depends on your individual needs. 

Speak to your doctor, clinical nurse specialist or pharmacist about your individual treatment plan.


You have blood tests before and during your treatment. They check your levels of blood cells and other substances in the blood. They also check how well your liver and kidneys are working.

What are the side effects of sodium clodronate?

Side effects can vary from person to person. They also depend on what other treatment you are having. 

When to contact your team

Your doctor, nurse, or pharmacist will go through the possible side effects. They will monitor you closely during treatment and check how you are at your appointments. Contact your advice line as soon as possible if:

  • you have severe side effects 

  • your side effects aren’t getting any better

  • your side effects are getting worse

Early treatment can help manage side effects better.

We haven't listed all the side effects here. Remember it is very unlikely that you will have all of these side effects, but you might have some of them at the same time.

Common side effects

Common side effects happen in more than 10 in 100 people (more than 10%). At the time of this review, there have been no reports of common side effects for this treatment.

Occasional side effects

These side effects happen in between 1 and 10 out of every 100 people (between 1 and 10%). You might have one or more of them. They include:


Contact your advice line if you have diarrhoea. For example, in one day you have 2 or more loose bowel movements than usual. If you have a stoma, you might have more output than normal. Your doctor may give you anti diarrhoea medicine to take home with you after treatment.

Try to eat small meals and snacks regularly. It’s best to try to have a healthy balanced diet if you can. You don’t necessarily need to stop eating foods that contain fibre. But if your diet is normally very high in fibre, it might help to cut back on high fibre foods such as beans, nuts, seeds, dried fruit, bran and raw vegetables. 

Drink plenty to try and replace the fluid lost. Aim for 8 to 10 glasses per day.

Feeling or being sick

Feeling or being sick is usually well controlled with anti sickness medicines. It might help to avoid fatty or fried foods, eat small meals and snacks and take regular sips of water. Relaxation techniques might also help.

It is important to take anti sickness medicines as prescribed even if you don’t feel sick. It is easier to prevent sickness rather than treat it once it has started.

This is usually due to the capsules irritating your stomach. Dividing the dose and taking half in the morning and half in the evening may help reduce sickness.

Low levels of calcium in the blood

You might get low calcium levels which are picked up in blood tests. Rarely low calcium levels can cause painful muscle spasms, cramps or muscle twitching. You might also get numbness or tingling in your feet, hands or around your mouth.

Let your healthcare team know if you develop any of these symptoms.

Liver changes

You might have liver changes that are usually mild and unlikely to cause symptoms. They usually go back to normal when treatment finishes. You have regular blood tests to check for any changes in the way your liver is working.

Rare side effects

These effects happens in fewer than 1 in 100 people (less than 1%). You might have one or more of them. They include:

  • difficulty in breathing
  • skin problems such as redness, peeling and itching
  • a fracture of the thigh bone that can cause sudden sharp pain in the hip, groin or thigh
  • increase in hormones that control the level of calcium in the your blood
  • kidney problems- you will have regular blood tests to check for any changes

Other side effects

There isn't enough information to work out how often these side effects might happen. You might have one or more of them. They include:

  • damage to the jaw bone (osteonecrosis) that can happen if you take sodium clodronate for a long period of time
  • bone, joint or muscle pain that can be severe
  • eye infection (conjunctivitis) – the eye may feel gritty, itchy, sticky from pus, watery and look red

Coping with side effects

We have more information about side effects and tips on how to cope with them.

What else do I need to know?

Other medicines, foods and drink

Cancer drugs can interact with some other medicines and herbal products. Tell your doctor or pharmacist about any medicines you are taking. This includes vitamins, herbal supplements and over the counter remedies.

It is important that you drink plenty of fluids while having sodium clodronate treatment so that you don't get dehydrated. 


This drug contains lactose (milk sugar). If you have an intolerance to lactose, contact your doctor before taking this medicine.


This drug contains sodium (salt). You might need to take account of this if you are on a controlled sodium diet. Tell your doctor if you are on a low salt diet. 

Loss of fertility 

You may not be able to become pregnant or get someone pregnant after treatment with this drug. Talk to your doctor before starting treatment if you think you may want to have a baby in the future.

Men might be able to store sperm before starting treatment. And women might be able to store eggs or ovarian tissue. But these services are not available in every hospital, so you would need to ask your doctor about this.    

Pregnancy and contraception

This treatment might harm a baby developing in the womb. It is important not to become pregnant or get someone pregnant while you're having treatment and for a few months afterwards.

Talk to your doctor or nurse about effective contraception before starting treatment. Let them know straight away if you or your partner become pregnant while having treatment.


Don’t breastfeed during this treatment because the drug may come through into your breast milk.

Treatment for other conditions

If you are having tests or treatment for anything else, always mention your cancer treatment. For example, if you are visiting your dentist.

More information about this treatment

For further information about this treatment and possible side effects go to the electronic Medicines Compendium (eMC) website. You can find the patient information leaflet on this website.

You can report any side effect you have to the Medicines Health and Regulatory Authority (MHRA) as part of their Yellow Card Scheme.

  • Electronic Medicines Compendium
    Accessed August 2021

  • Early and locally advanced breast cancer: diagnosis and management
    The National Institute for Health and Care Excellence (NICE), July 2018

  • Myeloma: diagnosis and management
    The National Institute for Health and Care Excellence (NICE), 2018

Last reviewed: 
22 Sep 2021
Next review due: 
22 Sep 2024

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