Mesna is a drug that is given with the chemotherapy drug ifosfamide, and sometimes with the chemotherapy drug cyclophosphamide. This should ideally be read with our information about ifosfamide or cyclophosphamide.

Ifosfamide and cyclophosphamide can irritate the lining of the bladder and make it bleed. Mesna protects your bladder. Drinking plenty of fluid will also help protect your bladder.

Your chemotherapy nurse will usually give 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 directed by your doctor.

Like other drugs, mesna can cause side effects. If these happen they are usually mild but occasionally can be severe. It is important to read the detailed information below so that you are aware of possible side effects. Tell your doctor or 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 doses high enough to cause bleeding from the bladder and so they will not need mesna. But mesna is given if your treatment involves having high doses of cyclophosphamide. Your doctor can tell you if you are having a high dose of cyclophosphamide.

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

You can help to protect your bladder during your treatment by:

  • drinking plenty of water – at least 2 litres (3½ pints) daily. Your nurse can tell you how much you should drink
  • emptying your bladder often during the treatment.

How mesna is given

Mesna can be given as:

  • a drip (infusion) into a vein at the same time as your chemotherapy
  • as a liquid that you drink. You can add the mesna to a 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 doctor, nurse or pharmacist can explain more about this to you
  • as a tablet. The tablets can be taken with food or on an empty stomach. If you are given tablets, it is important to take them as exactly as your healthcare professional explains.

About side effects

We explain the most common side effects of this treatment here. We also include some less common side effects.

You may get some of the side effects we mention, but you are unlikely to get all of them.

If you are also having treatment with other cancer drugs, you may have some side effects that we haven’t listed here.

Always tell your doctor, nurse or pharmacist about any side effects you have.

Your doctor can give you drugs to help control some side effects. It is important to take them exactly as your nurse or pharmacist explains. This means they will be more likely to work for you. Your nurse will give you advice about managing your side effects. After your treatment is over, most side effects start to improve.

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 doctor or nurse about the side effects you have.

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.

Contact the hospital

Your nurse will give you telephone numbers for the hospital. If you feel unwell or need advice, you can call them at any time of the day or night. 

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

More information

We cannot list every side effect for this treatment. There are some rare side effects that are not listed. You can visit the electronic Medicines Compendium (eMC) for more detailed information.

Possible side effects of mesna

Allergic reactions

Rarely, mesna may cause an allergic reaction. Your nurse will check you for this. If you have a reaction, they will treat it quickly. Allergic reactions are most common with the first few doses. A reaction is usually mild. Rarely, it can be more severe.

Signs of an allergic reaction can include:

  • 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 such as a headache, feeling flushed, having a fever, chills or dizziness.

Tell your nurse straight away if you notice any of these symptoms.

If you develop any of these symptoms or feel unwell 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

Your doctor can prescribe anti-sickness drugs to help prevent or reduce sickness. If you are sick after taking mesna by mouth, contact the hospital for advice. It is important you do not miss a dose of mesna so that your bladder lining is protected.

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.

Try using herbs and spices (unless you have a sore mouth or ulcers) or strong-flavoured sauces to give your food more flavour. Sucking boiled sweets or chewing gum can sometimes help get rid of a bitter or metallic taste. Your nurse can give you more advice.


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

Tummy pain

You may get pain or discomfort in your tummy (abdomen), feel bloated or wind. Your doctor can prescribe drugs to help improve these symptoms. Tell them if the pain doesn’t improve or gets worse.


If you have diarrhoea, contact the hospital for advice. Try to drink at least 2 litres (3½ pints) of fluids every day. It can help to avoid alcohol, caffeine, milk products, high-fat foods and high-fibre foods.


Feeling very tired is a common side effect. It’s often worse towards the end of treatment and for some weeks after it’s 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, don’t 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 prescribe 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

Occasionally, 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 the side effects become 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 be harmful to take when you are having cancer treatment.

Tell your doctor about any drugs you are taking, including vitamins, herbal drugs and complementary therapies. This includes medicines and supplements you can buy in a shop or chemist.

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.