Individual research recommendation details

Recommendation ID

CG183/3

Question

Using selective cyclooxygenase 2 inhibitors in people with previous severe allergic reactions to non-selective non-steroidal anti-inflammatory drugs:- Should all patients who have experienced a severe allergic reaction to a non-selective non-steroidal anti-inflammatory drug (NSAID) be assessed by specialist drug allergy services or should they be advised to take a selective cyclooxygenase 2 (COX 2) inhibitor without further investigations if clinically appropriate?

Any explanatory notes
(if applicable)

There are about 5.4 million people with asthma in the UK, 1–5% of whom are unable to take non-selective NSAIDs without developing a severe and sometimes life-threatening asthma attack. In addition, 0.1–1% of the general population report allergic reactions to NSAIDs with symptoms ranging from urticaria and angioedema to anaphylaxis. NSAIDs are extremely widely used, available over the counter and present within many compound preparations (for example, cold and flu remedies). People who are allergic to NSAIDs are therefore at risk of inadvertent exposure and this presents a significant public health issue. Commonly encountered NSAIDs such as aspirin, ibuprofen, diclofenac and naproxen are non-selective COX-2 inhibitors that block the enzymatic effects of both cyclooxygenase 1 (COX-1) and COX-2. More recently introduced NSAIDs include a group which are selective inhibitors of the COX-2 isoform alone. Studies have shown that the allergic response to NSAIDs is mediated through inhibition of COX-1 and therefore the majority of people with a history of allergic reactions to non-selective NSAIDs are able to tolerate selective COX-2 inhibitors. However, the same studies have also reported that a small proportion of these people also react adversely to selective COX-2 inhibitors. This group has not been properly characterised and therefore it is not possible to predict who should be offered a selective COX-2 inhibitor without undertaking specialist drug allergy investigations. This clinical guideline recommends that people who have had a mild reaction to a non-selective NSAID could be offered a selective COX-2 inhibitor but that all those who have had a severe reaction, such as anaphylaxis, severe angioedema or an asthmatic reaction, should not be offered a selective COX-2 inhibitor in a non-specialist setting. Well-designed, appropriately powered, controlled studies characterising people with a history of severe reactions to non-selective NSAIDs may enable them to have treatment with an anti-inflammatory without specialist drug allergy investigation.

Source guidance details

Comes from guidance

Drug allergy: diagnosis and management

Number

CG183

Date issued

September 2014

Other details