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Royal Brompton & Harefield NHS Foundation Trust
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Drug allergy

Credit: NHS Photo Library
Many people are referred to our service with a suspected drug allergy. Around 5–10% of people who have a problem with a drug are suffering from a drug allergy. This can be an allergy to a drug they have been prescribed by their GP, or an investigation of a reaction to a drug they had in a hospital. The most common symptoms of an allergy to a drug include:
  • rash  
  • itchy face and eyes
  • hives 
  • wheeze
  • facial swelling 
  • anaphylaxis

Many drugs can cause allergic reactions, but common examples include:
  • penicillin and other antibiotics 
  • aspirin and other non-steroidal anti-inflammatory drugs, such as ibuprofen
  • anaesthetic drugs
  • anti-convulsant drugs
  • chemotherapy drugs

Other substances that can cause similar reactions include the contrast dye used during X-rays or CT scanning, skin cleaning agents used in hospitals and latex.

Confirming the nature and cause of a previous allergic reaction

It is important to distinguish an allergic reaction to a drug from a side-effect, such as nausea. This can often be done simply by asking about what symptoms occurred and when, but sometimes further tests are indicated. For some drugs, skin testing can be used to identify the presence of allergic sensitisation. When this is not possible, or when skin testing has failed to provide a clear answer, readministration of the medication, under controlled conditions, in a step-wise manner may be needed.

We perform about 6–10 drug challenges every month, to confirm whether or not a drug was the cause of a reaction, but more often to identify safe alternatives.  

Royal Brompton

Sydney Street,
London SW3 6NP
Tel: +44 (0)20 7352 8121


Read about the allergy clinics held by the Trust