Mesna is a drug that is given with the chemotherapy drug ifosfamide. It is sometimes given with the chemotherapy drug cyclophosphamide. 

This page should ideally be read with our information about ifosfamide or cyclophosphamide.

Ifosfamide and cyclophosphamide can irritate the lining of the bladder, causing it to bleed. 

Mesna helps protect your bladder. Drinking plenty of fluid also helps protect your bladder.

Your chemotherapy nurse usually gives you mesna as a drip (infusion) into a vein at the same time as your chemotherapy. 

You can also take it by mouth, either as tablets or as a liquid to drink. It is important to take mesna as instructed by your cancer doctor.

Mesna can cause side effects. If these happen they are usually mild, but sometimes can be severe. 

It is important to read the detailed information below so you know about the possible side effects. 

Tell your cancer doctor or specialist nurse if you notice any changes.

Why mesna is given

The drugs ifosfamide and cyclophosphamide can sometimes irritate the lining of the bladder. 

This can cause bleeding from the bladder, which means you may have blood in your urine (pee). This is called haematuria. 

Mesna helps protect your bladder to prevent irritation and bleeding.

Mesna is always given with ifosfamide. Most people who have treatment with cyclophosphamide are not given high enough doses to cause bleeding from the bladder, so they do not need mesna. 

But, if your treatment involves having high doses of cyclophosphamide you are given mesna. 

Your doctor can tell you if you are having a high dose of cyclophosphamide.

While you are having mesna, your urine is tested for signs of blood. If you have blood in your urine, you will be given extra mesna.

You can help protect your bladder during treatment by:

  • drinking plenty of water – usually at least 2 litres (3½ pints) each day
  • emptying your bladder (peeing) often during the treatment.

How mesna is given

Mesna can be given as one of the following:

  • Your nurse may give it as a drip (infusion) into a vein at the same time as your chemotherapy.
  • You can drink it as a liquid. You might want to add the mesna to a flavoured soft drink, such as orange juice or cola, to help it taste nicer. It can be kept in a refrigerator for up to 24 hours after mixing. Your cancer doctor, specialist nurse or pharmacist can explain more about this to you.
  • You can take it as a tablet. These can be taken with or without food. If you are given tablets, it is important to take them as exactly as your healthcare professional explains.

Serious and life-threatening side effects

Sometimes, cancer drugs can result in very serious side effects. Rarely, these may be life-threatening. 

Your cancer doctor and 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.

Possible side effects of mesna

Some people have very few side effects while others may have more. The side effects described below will not affect everyone taking mesna.

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 doctor or nurse.

It is often difficult to know which side effects may be caused by mesna and which ones may be caused by the chemotherapy. 

Always tell your cancer doctor or specialist nurse about the side effects you have.

Your nurse will give you 24-hour contact numbers for the hospital. You can call them if you feel unwell or need advice any time of day or night. 

Save these numbers in your phone or keep them somewhere safe.

Allergic reaction

Rarely, this treatment may cause an allergic reaction.

Signs of an allergic reaction can include:

  • a faster heartbeat
  • swelling in your face
  • skin reactions
  • breathlessness
  • pain in your back, tummy or chest
  • a rash or bruising on your skin
  • flu-like symptoms.

Tell the nurse straight away if you think you may be having an allergic reaction. 

If you develop these symptoms when you are at home, contact the hospital straight away on the number you have been given. They can give you advice.

Feeling or being sick

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.

If you are sick after taking mesna by mouth, contact the hospital for advice. This is because you may not get the full dose and your bladder will not be protected. 

If this happens, contact your doctor to check if you need to take more mesna tablets.

Taste changes

You may get a bitter or metallic taste in your mouth, or find that food tastes different. This should go away when your treatment finishes. 

Sucking boiled sweets or chewing gum may help. Try using herbs and spices (unless you have a sore mouth or ulcers) or strong-flavoured sauces to give your food more flavour. 

Your nurse can give you more advice.


Mesna may cause headaches. If this happens, tell your doctor or nurse. They can give you painkillers.

Tummy pain

You may get pain or discomfort in your tummy (abdomen), feel bloated or have wind. 

Your doctor can prescribe drugs to help improve these symptoms. Tell them if the pain does not improve or gets worse.


Tell your doctor if you have diarrhoea or constipation. They can give you medicine to help with this. 

Remember to have at least 2 litres (3½ pints) of fluids a day.


Feeling very tired is a common side effect. It is often worse towards the end of treatment and for some weeks after it is finished. 

Try to pace yourself and get as much rest as you need. It helps to balance this with some gentle exercise, such as short walks. 

If you feel sleepy, do not drive or operate machinery.

Limb and joint pain

You may get pain in your joints or limbs for a few days after treatment. 

Tell your doctor if this happens so they can give you painkillers. Let them know if the pain does not get better. 

Try to get plenty of rest. Taking regular warm baths may help.

Skin changes

Mesna may affect your skin. Your doctor or nurse can tell you what to expect. 

If your skin feels dry, try using an unperfumed moisturising cream every day. Mesna can cause a rash, which may be itchy. 

Always tell your doctor or nurse about any skin changes. They can give you advice and may prescribe creams or medicines to help. 

Any changes to your skin are usually temporary and improve when treatment finishes.

Mood and behaviour changes

Sometimes, mesna can affect your mood. You may feel irritable and have mood swings. 

Tell your doctor or nurse if you have any of these side effects. They may make some changes to your treatment if this becomes a problem.

Other information

It is 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.

Medical and dental treatment

If you need medical treatment for any reason other than cancer, always tell the doctors and nurses that you are having cancer treatment. 

Give them the contact details for your cancer doctor so they can ask for advice.

If you think you need dental treatment, talk to your cancer doctor or nurse. Always tell your dentist you are having cancer treatment.

Other medicines

Some medicines can affect chemotherapy or be harmful when you are having it. This includes medicines you can buy in a shop or chemist. 

Tell your cancer doctor about any drugs 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.