Decitabine (Dacogen) | Cancer Research UK
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What decitabine is

Decitabine is a drug used to treat acute myeloid leukaemia. It is pronounced dee-sit-ay-been. It has the brand name Dacogen.

Decitabine is a treatment for people aged over 65 years who can't have standard induction chemotherapy for acute myeloid leukaemia.

Decitabine is being used in clinical trials for a number of other cancers including advanced stomach cancer, oesophageal cancer and ovarian cancer. It is also being used in trials for the blood disorder myelodysplastic syndrome.


How decitabine works

Decitabine is a type of drug called a hypomethylating agent. It works by switching off a protein called DNA methyltransferase. This switches on genes that stop the cancer cells growing and dividing.


How you have decitabine

You have decitabine as a drip into your bloodstream (intravenously). You can have it through a thin, short tube (a cannula) put into a vein in your arm each time you have treatment. Or you may have it through a central line, a portacath, or a PICC line. These are long, plastic tubes that give the drugs directly into a large vein in your chest. You have the tube put in before or during your course of treatment and it stays in place as long as you need it.

The drip takes about 1 hour.

You can read our information about having chemotherapy into a vein.

You usually have decitabine as a course of several cycles of treatment. The number of cycles depends on your treatment plan. Most people have at least 4 cycles.

Each cycle takes 4 weeks. You start by having decitabine daily for 5 days. Then you don't have any treatment for the next 23 days. You then start the next treatment cycle. You continue with the treatment for as long as it is working.


Tests during treatment

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


About side effects

We've listed the side effects associated with decitabine. You can use the links to find out more about each side effect. Where there is no link, please go to our information about cancer drug side effects or use the search box at the top of the page.

You may have a few side effects. They may be mild or more severe. A side effect may get better or worse through your course of treatment. Or more side effects may develop as the course goes on. This depends on

  • How many times you've had the drug before
  • Your general health
  • The amount of the drug you have (the dose)

The side effects may be different if you are having decitabine with other medicines.

Tell your doctor or nurse straight away if any of the side effects get severe.


Common side effects

More than 10 in 100 people have one or more of these effects.

  • An increased risk of getting an infection from a drop in white blood cells – it is harder to fight infections and you can become very ill. You may have headaches, aching muscles, a cough, a sore throat, pain passing urine, or you may feel cold and shivery. If you have a severe infection this can be life threatening. Contact your treatment centre straight away if you have any of these effects or if your temperature goes above 38°C
  • Tiredness and breathlessness due to a drop in red blood cells (anaemia) – you may need a blood transfusion
  • Bruising more easily due to a drop in platelets – you may have nosebleeds, or bleeding gums after brushing your teeth. Or you may have lots of tiny red spots or bruises on your arms or legs (known as petechiae)
  • A cough occurs in about 4 out of 10 people (40%)
  • Diarrhoea affects 3 out of 10 people (30%) – drink plenty of fluids. If your diarrhoea is severe or continues you could get dehydrated so let your doctor or nurse know
  • Feeling or being sick – this is usually well controlled with anti sickness medicines
  • Headaches affect just over 1 in 10 people (10%)
  • Difficulty sleeping
  • Low levels of potassium (hypokalaemia) and magnesium (hypomagnesia) in your blood
  • Muscle pain and aching joints
  • Chest pain and breathlessness (sometimes with a high temperature or cough) – this is due to a lung infection (pneumonia). Contact your treatment centre straight away if you have any of these effects or if your temperature goes above 38°C
  • Loss of fertility – you may not be able to become pregnant or father a child after this treatment. Talk to your doctor before starting treatment if you think you may want to have a baby in the future. Men may be able to store sperm before starting treatment

Occasional side effects

Between 1 and 10 in every 100 people have one or more of these.

  • A sore mouth
  • Feeling weak, a high temperature and chills
  • An allergic reaction – let your nurse or doctor know straight away if you have a sudden skin rash, itching, breathlessness or swelling of the lips, face or throat
  • A stroke or mini stroke – tell your nurse or doctor straight away if you have a sudden severe headache or facial weakness, arm weakness, or speech problems
  • Dark poo (stools) due to bleeding into the stomach or bowel – let your nurse or doctor know if you have this
  • A sore or runny nose
  • Sinus pain

Rare side effects

Fewer than 1 in 100 people have these effects.

  • Red, lumpy painful patches on the skin with a high temperature and high white blood cell levels. This collection of effects is called acute febrile neutrophilic dermatosis or Sweets syndrome. Tell your doctor or nurse straight away if you have them
  • Inflammation of the bowel causing tummy (abdominal) pain, bloating or diarrhoea

Important points to remember

Talk to your doctor, pharmacist or nurse about all your side effects so that they can help you manage them. They can give you advice or reassure you. Your nurse will give you a contact number to ring if you have any questions or problems. If in doubt, call them.

Other medicines

Tell your doctor about any other medicines you are taking, including vitamins, herbal supplements and over the counter remedies. Some drugs can react together.

Pregnancy and contraception

This drug may have a harmful effect on a developing baby. It is important not to become pregnant or father a child during treatment. Talk to your doctor or nurse about contraception before starting treatment. Men need to use reliable contraception while having the drug and for about 3 months afterwards. Women should talk to their doctor about when it is safe to become pregnant after treatment. 


Don't breastfeed during this treatment because the drug may come through in the breast milk.

Potassium and sodium in decitabine

This medicine contains potassium and sodium. Let your doctor know if you are on a controlled potassium or low sodium diet. 



You should not have immunisations with live vaccines while you are having this treatment or for at least 6 months afterwards. In the UK, these include rubella, mumps, measles (usually given together as MMR), BCG, yellow fever and Zostavax (shingles vaccine).

You can have other vaccines, but they may not give you as much protection as usual until your immune system has fully recovered from your treatment. It is safe to have the flu vaccine.

It is safe for you to be in contact with other people who've had live vaccines as injections. There can be problems with vaccines you take by mouth (oral vaccines) but not many people in the UK have these now. So there is usually no problem in being with any baby or child who has recently had any vaccination in the UK. You might need to make sure that you aren't in contact with anyone who has had oral polio, cholera or typhoid vaccination recently, particularly if you live abroad.


More information about decitabine treatment

This information does not list all the very rare side effects of this treatment that are very unlikely to affect you. For further information look at the Electronic Medicines Compendium website at

If you have a side effect not mentioned here that you think may be due to this treatment you can report it to the Medicines Health and Regulatory Authority (MHRA) at

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Updated: 7 December 2015