Emergency Medicine

Allergic or Immunological Conditions

110 General Medical Emergencies

PERIARTICULAR SWELLINGS

See pp. 326–330 in Section X, Musculoskeletal and Soft-Tissue Emergencies.

ALLERGIC OR IMMUNOLOGICAL CONDITIONS

The following immunological conditions may present, ranging from those that

are socially inconvenient to imminently life-threatening:

● Urticaria (hives)

● Angioedema

● Anaphylaxis – see page 27 (Section I, Critical Care).

Urticaria (hives)

DIAGNOSIS

1 There are many immunological and non-immune causes, including:

(i) Foods – nuts, shellfish, eggs, strawberries, chocolate, food dyes or

preservatives.

(ii) Drugs – penicillin, sulphonamide, aspirin, NSAIDs, codeine,

morphine.

(iii) Insect stings, animals, parasitic infections including nematodes

(in children).

(iv) Physical – cold, heat, sun, pressure, exercise.

(v) Systemic illness – malignancy including Hodgkin’s lymphoma,

vasculitis, viruses such as hepatitis A or Epstein–Barr virus (EBV)

and serum sickness.

(vi) Idiopathic (in >90% of chronic cases).

2 Itchy, oedematous, transient skin swellings are seen, which may occur in

crops lasting several hours.

MANAGEMENT

1 Give the patient a less sedating H 1 histamine antagonist such as loratadine

10 mg orally daily. This is minimally sedating, unlike promethazine.

(i) Refractory cases may respond to the addition of an H 2 histamine

antagonist such as ranitidine 150 mg orally b.d.

2 Attempt to identify the likely cause from the recent history. Most reactions

occur within minutes but may be delayed for up to 24 h.

3 Observe for any multi-system involvement suggesting progression to ana-

phylaxis (see p. 27).