Clodronate is a type of drug called a bisphosphonate. It’s used to treat osteoporosis.  This is a condition when the bones become thinner or weaker. Some illnesses, like myeloma or secondary cancer of the bone, can cause weakness in the bones.
Normally, two kinds of bone cell work together to keep bones healthy:

  • osteoclasts destroy old bone
  • osteoblasts build new bone.

Some cancers can cause osteoclasts to work too hard, destroying more bone cells than are created. This can weaken the bone, cause pain, or increase the amount of calcium in the blood.  Clodronate can slow the action of osteoclasts, allowing the bone to recover. It also helps to lower raised calcium levels in the blood.

Clodronate tablets or capsules are usually taken once or twice a day. There are some side effects associated with clodronate. Not everyone having the treatment will have all the side effects. Any changes should be discussed with your doctor or nurse.

Clodronate (Bonefos®, Clasteon®, Loron®)

Clodronate belongs to a group of drugs called bisphosphonates. Bisphosphonates are commonly used to treat bone thinning (osteoporosis). In certain situations, they can help protect your bones against some of the effects of secondary bone cancer, like pain and weakness. Secondary bone cancer occurs when cells from the original (primary) cancer spread to form a new tumour (secondary cancer or metastasis) in the bone.

Clodronate is often given alongside other cancer treatments. As well as being used in some types of secondary bone cancer, it can also help people with myeloma, a cancer of the plasma cells in the blood. It’s also used to lower a raised calcium level in the blood.

The effect of cancer on the bones

When bones are affected by secondary cancer, increased amounts of calcium (the substance that helps to build bones) may be released into the blood. A raised level of calcium in the blood is known as hypercalcaemia. This can cause symptoms such as feeling or being sick (nausea or vomiting), tiredness, irritability and sometimes confusion. Clodronate can help reduce high levels of calcium.

Secondary cancer in the bones may make them weak, and in some situations they may break (fracture). Clodronate can help to strengthen the bone and reduce the risk of fractures.

Cancer can affect the bones in different ways, and clodronate is only helpful for some cancers that affect the bones. Your doctor or specialist nurse can tell you if it would be helpful for you.

Clodronate (Bonefos®, Clasteon®, Loron®)

In normal bone, two types of cells called osteoclasts and osteoblasts work together constantly to shape, rebuild and strengthen existing bone:

  • osteoclasts destroy old bone
  • osteoblasts build new bone.

Myeloma and some secondary bone cancers can produce chemicals that make the osteoclasts work harder. This means that more bone is destroyed than rebuilt, which leads to weakening of the affected bone. This can cause pain and means that the bone can fracture or break more easily.

Clodronate targets areas of bone where the osteoclast activity is high. It helps bring the balance of osteoclast and osteoblast activity back to normal by reducing the activity of the osteoclasts. This can reduce pain and help strengthen the bone. It also means that less calcium will be lost from the bones.

How clodronate is given

Clodronate is given as tablets or capsules, usually taken once or twice a day. It’s important to take the clodronate as directed. You must not eat or have any milk or any other medicines for 1-2 hours before and after taking clodronate, otherwise your body will not absorb the drug properly. Your nurse, doctor or pharmacist will explain this to you. You should avoid taking clodronate with mineral supplements for the same reason.

How long clodronate is given for

If you are having clodronate to lower your calcium level, you may be given tablets or capsules to maintain your calcium at a normal level. If your calcium level is very high, you may also be given a single dose of a bisphosphonate drug into the vein (intravenously) to bring it down faster.

If you are having clodronate to reduce pain or strengthen your bones, then you may need to take it for as long as it seems to be working.

Clodronate (Bonefos®, Clasteon®, Loron®)

Some people have very few side effects while others may experience more. The side effects described below won't affect everyone who has clodronate and may be different if you are having more than one drug. We have outlined the most common side effects but haven't included those that are rare and therefore unlikely to affect you. If you notice any effects that aren't listed below, discuss them with your doctor or nurse.

Abdominal (tummy) pain and diarrhoea

Sometimes, clodronate can cause diarrhoea. This can usually be controlled with medicine, but let your doctor know if it's severe or continues.

Feeling sick (nausea) or being sick (vomiting)

This is uncommon and usually mild. It can be controlled with anti-sickness (anti-emetic) tablets.

Less common side effects

Tingling sensation in lips or tongue

This can happen if the calcium level in the blood drops below normal. This is rare and usually only temporary. Your doctor will carry out regular blood tests to monitor the level of calcium in your blood.

Change in kidney function

Clodronate can sometimes affect how your kidneys work. This doesn’t normally cause any symptoms and the effects are generally mild. Your doctor will check how well your kidneys are working during your treatment by doing blood tests.

Jaw problems (osteonecrosis)

A rare side effect of clodronate is a condition called osteonecrosis of the jaw. This is when healthy bone tissue in the jaw becomes damaged and dies. Gum disease, problems with your dentures and some dental treatments, like having a tooth removed, can increase the risk of this. So before you start taking the drug you'll be advised to have a full dental check-up.

During treatment with bisphosphonates, it's very important to look after your teeth by brushing them regularly and having routine dental check-ups. Always let your dentist know that you're taking bisphosphonates. Some of the symptoms of osteonecrosis can include pain, swelling, redness of the gums, loose teeth or a feeling of numbness or heaviness in your jaw. Tell your cancer specialist and dentist straight away if you have any of these symptoms.

Additional information

Admission to hospital

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

Emergency contacts

It’s a good idea to find out who you should contact if you have any problems or troublesome side effects when you’re at home.

Back to Bisphosphonates

Bisphosphonates for myeloma

Bisphosphonates are drugs that can strengthen weakened bones and reduce pain. Research has shown that some bisphosphonates may help treat myeloma.

Zoledronic acid

Zoledronic acid is a drug that can be used when cancer has spread to the bones. It also helps to lower raised calcium levels in the blood.


Pamidronate is a drug that can be used when cancer has spread to the bones. It also helps to lower raised calcium levels in the blood.