When should I consider referring a patient with severe hypersensitivity reactions to an allergist for further evaluation?

Consider referring a patient with severe hypersensitivity reactions to an allergist for further evaluation in the following situations:

• If the patient has had a suspected anaphylactic reaction or a severe non-immediate cutaneous reaction such as drug reaction with eosinophilia and systemic symptoms (DRESS), Stevens–Johnson Syndrome, or toxic epidermal necrolysis NICE CG183.
• If the patient has had a suspected allergic reaction to a non-selective NSAID with symptoms such as anaphylaxis, severe angioedema, or an asthmatic reaction NICE CG183.
• If the patient has had anaphylaxis or another suspected allergic reaction during or immediately after general anaesthesia NICE CG183.
• If the patient has had a suspected allergy to beta-lactam antibiotics and either needs treatment with these antibiotics or is likely to need them frequently in the future NICE CG183.
• After emergency treatment for suspected anaphylaxis, patients should be offered referral to a specialist allergy service for accurate investigation, diagnosis, monitoring, and ongoing management NICE CG134.
• In children or young people, consider referral if there have been one or more acute systemic reactions or severe delayed reactions, or if there is confirmed IgE-mediated food allergy with concurrent asthma NICE CG116.

In summary, referral to an allergist is indicated for severe or systemic hypersensitivity reactions, reactions involving anaphylaxis, severe cutaneous reactions, reactions to critical drug classes where alternative treatment options are limited, and after emergency treatment for anaphylaxis to ensure specialist assessment and management.