HSR information for patients and carers

About 5 in every 100 patients treated with abacavir in a clinical trial who did not have a gene called HLA-B*5701 developed a hypersensitivity reaction (a serious allergic reaction).

In clinical trials where patients who had the HLA-B*5701 gene were excluded, about 1 in 100 patients treated with abacavir experienced the hypersensitivity reaction.

Who gets these reactions?

Anyone taking medicines which contain abacavir could develop a hypersensitivity reaction to abacavir, which could be life threatening if they continue to take abacavir.

You are more likely to develop such a reaction if you have the HLA-B*5701 gene (but you can get a reaction even if you do not have this gene). You should have been tested for this gene before any abacavir-containing medication was prescribed for you. If you know you have this gene, tell your doctor before you take abacavir.

What are the symptoms?

Click on the dots for the symptoms.


The most common symptoms are:

  • Fever (high temperature) and skin rash

Other common symptoms are:

  • Nausea (feeling sick), vomiting (being sick), diarrhoea, abdominal (stomach) pain, severe tiredness

Other symptoms include:

  • Pains in the joints or muscles, swelling of the neck, shortness of breath, sore throat, cough, headache
  • Occasionally, inflammation of the eye (conjunctivitis), mouth ulcers, low blood pressure

If you continue to take abacavir, the symptoms will get worse, and may be life-threatening.

When do these reactions happen?

Hypersensitivity reactions can start at any time during treatment with abacavir, but are more likely during the first 6 weeks of treatment.

Occasionally, reactions have developed in people who start taking abacavir again, and had only one symptom on the Alert Card before they stopped taking it.

Very rarely, reactions have developed in people who start taking abacavir again, but who had no symptoms before they stopped taking it.

If you are caring for a child who is being treated with abacavir-containing medication, it is important that you understand the information about this hypersensitivity reaction. If your child gets the symptoms described below it is essential that you follow the instructions given.

Contact your doctor immediately:

  1. If you get a skin rash, OR
  2. If you get symptoms from at least 2 of the following groups:
    1. Fever
    2. Shortness of breath, sore throat or cough
    3. Nausea or vomiting, diarrhoea or abdominal pain
    4. Severe tiredness or achiness, or generally feeling ill

Your doctor may advise you to stop taking abacavir.


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