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Information about Ziagen

What is it and what is it used for?

Ziagen is used in combination with other antiviral medicines to treat patients who are infected with human immunodeficiency virus (HIV), the virus that causes acquired immune deficiency syndrome (AIDS).

The medicine can only be obtained with a prescription.

How Ziagen works
The active substance in Ziagen, abacavir, is a nucleoside reverse transcriptase inhibitor (NRTI). It works by blocking the activity of reverse transcriptase, an enzyme needed by HIV to produce the genetic instructions for making more viruses once it has infected the cell. Ziagen, taken in combination with other antiviral medicines, reduces the amount of HIV in the blood and keeps it at a low level. It does not cure HIV infection or AIDS, but it can hold off the damage to the immune system and avoid the development of infections and diseases associated with AIDS.

How Ziagen is used
Ziagen should be prescribed by a doctor who has experience in the management of HIV infection.

Before starting treatment with abacavir, all patients should have a test to find out if they have a gene called ‘HLA‑B (type 5701)’. Patients with this gene are at an increased risk of having an allergic reaction to abacavir, so they should not take Ziagen.

The recommended dose of Ziagen for adults and children weighing at least 25 kg is 600 mg daily. This can be taken either as a single daily dose or divided into 300 mg twice a day. In children weighing less than 25 kg the recommended dose depends on body weight. Patients who cannot swallow tablets should use the oral solution, or alternatively they may crush the tablets and add them to a small amount of food or drink immediately before swallowing it. For more information, see the package leaflet.

What are the benefits?

The European Medicines Agency noted that the demonstration of the benefit of Ziagen was based on the results of studies mainly carried out with the medicine taken twice a day in combination with other medicines in adults who had not taken HIV treatment before.

Based on its review of the quality, safety and effectiveness of the medicine, the Agency decided that Ziagen’s benefits are greater than its risks and recommended that it be given marketing authorisation.

What are main side effects?

The most common side effects with Ziagen (seen in between 1 and 10 patients in 100) are:
  • loss of appetite
  • headache
  • nausea (feeling sick)
  • vomiting
  • diarrhoea
  • rash
  • fever
  • lethargy (lack of energy)
  • tiredness
Hypersensitivity reactions (allergic reactions) occur in patients taking Ziagen, usually within the first six weeks of treatment, and can be life-threatening. The risk of hypersensitivity is higher in patients who have the HLA‑B (type 5701) gene. Symptoms almost always include fever or rash, but also very commonly include nausea, vomiting, diarrhoea, abdominal pain (stomach ache), dyspnoea (difficulty breathing), cough, fever, lethargy, malaise (feeling unwell), headache, signs of liver damage in the blood and myalgia (muscle pain). Treatment with Ziagen should be stopped promptly if the patient has a hypersensitivity reaction.

For the full list of all side effects and restrictions with Ziagen, see the patient leaflet.

What studies have been done?

In all of the studies, Ziagen caused a decrease in viral loads, particularly when taken with other antiviral medicines.

It was more effective than placebo, and was as effective as other antiviral medicines in reducing viral loads in all age groups. In one of the studies in adults, 77% of the patients taking Ziagen with lamivudine and zidovudine had viral loads below 400 copies/ml after 16 weeks (67 out of 87), compared with 38% of the adults taking lamivudine and zidovudine without Ziagen (33 out of 86).

Once- and twice-daily Ziagen had similar effects on viral load. Patients receiving Ziagen also had increases in their CD4 cell counts.


Ziagen was first approved for use in the EU in 1999.  It is manufactured by ViiV.

European Medicines Agency website page Ziagen (accessed 29/07/18)
NICE website
SMC website

Links available in External Resources

Reporting of suspected adverse reactions

Reporting suspected adverse reactions (side effects) after authorisation of the medicinal product is important. It allows continued monitoring of the benefit/risk balance of the medicinal product. Healthcare professionals or patients are asked to report any suspected adverse reactions via the Yellow Card Scheme at or search for MHRA Yellow Card in the Google Play or Apple App Store.

Disclaimer: This site is designed to offer information for general educational purposes only. The health information furnished on this site and the interactive responses are not intended to be professional advice and are not intended to replace personal consultation with a qualified physician, pharmacist, or other healthcare professional. We cannot provide individual medical advice. You must always seek the advice of a professional for questions related to a disease, disease symptoms, and appropriate therapeutic treatments.

For the full list of side effects and restrictions, see the package leaflet (link to package leaflet available in External Resources).