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Idelalisib (Zydelig)

Find out what idelalisib is, how you take it and other important information about taking this drug. 

What is it

Idelalisib is pronounced eye-dell-al-iss-ib. It is also called by its brand name Zydelig. It is a type of biological therapy.

Idelalisib is a treatment for:  

  • chronic lymphocytic leukaemia (CLL) with another drug called rituximab (Mabthera)
  • follicular non Hodgkin lymphoma (NHL)
  • other types of cancer as part of clinical trials

Idelalisib for chronic lymphocytic leukaemia (CLL) 

Idelalisib is used for CLL if your leukaemia is no longer responding to other treatments and has come back within 2 years. Or you may have it as a first treatment if your CLL has specific gene changes known as 17p deletion or TP53 mutation. 

Idelalisib for non Hodgkin lymphoma (NHL)

You might have idelalisib for NHL if you have had at least 2 other types of treatment and they are no longer working. 

How it works

This type of drug works by blocking particular proteins inside cancer cells that encourage the cancer to grow. Idelalisib blocks a protein called PI3K and is called a PI3K inhibitor. 

Some lymhoma and leukaemia cells have too much PI3K. So by blocking this protein, idelalisib may shrink the cancer or stop it growing for a time. 

How you have it

You take idelalisib as a tablet twice a day. You can take it with or without food. 

Don't chew or crush the tablet. You should swallow it whole with a glass of water. 

Taking your tablets or capsules

You must take tablets and capsules according to the instructions your doctor or pharmacist gives you.

You should take the right dose, not more or less.

Never stop taking a cancer drug without talking to your specialist first.

When you have it

You usually carry on taking idelalisib for as long as it is working. 

Tests during treatment

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

Side effects

Important information

Other medicines, foods and drink

Drugs can interact with some other medicines and herbal products. Tell your doctor about any medicines you are taking. This includes vitamins, herbal supplements and over the counter remedies.

Many medicines, foods and herbal supplements can react with idelalisib. In particular medicines, foods and herbal supplements which contain CYP enzymes. 

Pregnancy and contraception

This treatment might harm a baby developing in the womb. It is important not to become pregnant or father a child while you are having treatment and for a few months afterwards. Talk to your doctor or nurse about effective contraception before starting treatment.


You may not be able to become pregnant or father a child after treatment with this drug. 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. Women may be able to store eggs or ovarian tissue but this is rare.


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

Treatment for other conditions

Always tell other doctors, nurses or dentists that you’re having this treatment if you need treatment for anything else, including teeth problems.


Don’t have immunisations with live vaccines while you’re having treatment and for at least 6 months afterwards.

In the UK, live vaccines include rubella, mumps, measles, BCG, yellow fever and Zostavax (shingles vaccine).

You can:

  • have other vaccines, but they might not give you as much protection as usual
  • have the flu vaccine
  • be in contact with other people who've had live vaccines as injections

Avoid contact with people who’ve had live vaccines taken by mouth (oral vaccines). This includes the rotavirus vaccine given to babies. The virus is in the baby’s urine for up to 2 weeks and can make you ill. So, you mustn't change their nappies for 2 weeks after their vaccination.

You also need to avoid anyone who has had oral polio or typhoid vaccination recently.

More information about this treatment

For further information about this treatment go to the electronic Medicines Compendium (eMC) website.

You can report any side effect you have to the Medicines Health and Regulatory Authority (MHRA) as part of their Yellow Card Scheme.

Last reviewed: 
22 Dec 2014
  • Electronic Medicines Compendium 
    Accessed December 2014

  • Influenza vaccines in immunosuppressed adults with cancer
    Noa Eliakim-Raz and others
    Cochrane Database of systematic reviews, 29 October 2013

  • Idelalisib in Relapsed Indolent Lymphoma 

    European Society for Medical Oncology (ESMO), March 2014

  • Idelalisib for the Treatment of Chronic Lymphocytic Leukemia

    M. Khan and others. ISRN Oncology, April 2014

  • PI3Kδ Inhibition by Idelalisib in Patients with Relapsed Indolent Lymphoma

    A. K. Gopal. New England Journal of Medicine, March 2014

Information and help

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