What is cyclophosphamide?

In some conditions where the immune system is overactive cyclophosphamide is used to suppress the immune system (by damaging raplidly multiplying cells) to bring the disease under control. Cyclophosphamide doesn't work straight away – it may take six weeks or more before you notice an improvement.

Cyclophosphamide is used to treat several different types of rheumatic disease, including:


Cyclophosphamide is often prescribed along with steroid tablets or steroid injections.

Your doctor will arrange for you to have blood and urine tests before you start treatment, as cyclophosphamide can affect the blood and the bladder. You'll then have regular checks while you're on cyclophosphamide. You should receive full information about the treatment plan before starting cyclophosphamide and you may be asked to sign a consent form.

How is it taken?

Cyclophosphamide can be taken:

  • either through a drip into a vein (intravenous infusion) which will need to be given in hospital
  • or as low doses of tablets (usually taken once a day) – these should be swallowed whole, not chewed, and should be taken with or after food and with plenty of water.

Your doctor will discuss the options with you. The dose will depend on your body weight and may change depending on how you respond to the drug.

How long does it take to work?

Cyclophosphamide doesn't work straight away. It may take six weeks or more to produce an effect, depending on your condition. It's important to attend for your planned infusions or take the tablets as directed (unless you have severe side-effects):

  • even if it doesn't seem to be working at first
  • even when your symptoms improve (to help keep your condition under control).

Side-effects and risks

A common side-effect of cyclophosphamide is feeling sick (nausea). Your doctor may prescribe medicine to control this.

Because cyclophosphamide affects your immune system, it can make you more likely to pick up infections. It can also make them harder to spot. Make sure you have your repeat blood tests and tell your doctor or rheumatology nurse straight away if you develop:

  • a sore throat, fever or other signs of infection
  • unexplained bruising or bleeding
  • any other new symptoms that concern you.

You should stop taking cyclophosphamide, try to get a prompt blood test, and see your doctor immediately if any of the above symptoms are severe.

You should also see your doctor if you get chickenpox or shingles or come into contact with someone who has chickenpox or shingles. These illnesses can be severe if you're on cyclophosphamide. You may need antiviral treatment, and your cyclophosphamide may need to be stopped until you're better.

One very important side-effect is inflammation and bleeding of the bladder wall (haemorrhagic cystitis). If this happens you may notice blood in your urine and you must see your doctor immediately. To reduce the risk of this happening, you should drink 8–10 glasses (2–3 litres) of non-alcoholic drinks or water a day. You may be prescribed a drug called mesna to try to reduce the risk of cystitis.

Cyclophosphamide can also affect the blood count, which means your body is making fewer blood cells.

Because cyclophosphamide can affect the blood and the bladder, your doctor will arrange for you to have blood and urine tests before and during treatment. You may be asked to keep a record of your test results in a booklet and to bring it with you when you visit your GP or the hospital.

You must not take cyclophosphamide unless you're having regular checks.

Sometimes cyclophosphamide can cause hair loss, mouth ulcers and irregular menstrual periods.

There's a slightly increased risk of certain types of cancer, particularly bladder cancer, but cyclophosphamide won't be prescribed unless your doctor thinks the benefits outweigh the risks.

Reducing the risk of infection

Effects on other treatments

Cyclophosphamide may be prescribed alongside other drugs (for example, steroids) to treat your condition. However, some drugs can interact with cyclophosphamide, so speak to your doctor before starting any new medications and remember to mention you're on cyclophosphamide if you're treated by anyone other than your usual healthcare team.


It's recommended that people on cyclophosphamide avoid live vaccinations such as yellow fever. However, sometimes a live vaccine may be necessary (for example, rubella immunisation in women of childbearing age).

If you're offered shingles vaccination (Zostavax) it's best to have this before starting cyclophosphamide. Shingles vaccination isn't recommended for people who are already on cyclophosphamide.

Pneumococcal vaccine (which protects against the commonest cause of pneumonia) and yearly flu vaccines are safe and recommended.


There's no particular reason to avoid alcohol while on cyclophosphamide.

Fertility, pregnancy and breastfeeding

Cyclophosphamide can reduce fertility in both men and women, though stopping the drug may reverse this effect. You should discuss this with your doctor, preferably before you start the treatment. There may be options available to help you preserve your fertility if this is important to you (for example, sperm storage).

You should not use cyclophosphamide if you're pregnant. Men and women taking cyclophosphamide must take contraceptive precautions, and should continue doing so for at least three months after treatment is stopped. If you're planning a family or if you become pregnant while taking cyclophosphamide, you should discuss this with your doctor as soon as possible.

You shouldn't breastfeed if you're on cyclophosphamide. The drug may pass into the breast milk and could be harmful to your baby.