Table 1.

Characteristics of the included studies

Study	Population	Risk Factors for Allergic Reactions	Prophylactic regime	Contrast agent	Reaction
Gates 1972 [13]	2000 adults undergoing IVP	History of allergic reactions taken, patients with positive history included	Diphenhydramine 10 mg ivi 1 minute prior to contrast	30–60 ml Renograffin 60 (Ionic)	Not defined
Small 1982 [14]	220 adults undergoing IVP	Patients taking anti-histamines excluded	Chlorpheniramine 10 mg sci 15 minutes prior to contrast	Not recorded	Hives, generalised pruritis
Bertrand 1992 [16]	400 adults undergoing IVP, CT or lower limb venography	Patients with history of allergy, atopy, drug sensitivity or previous reactions to contrast excluded	Hydroxyzine 100 mg po 12 hours prior to contrast	Meglumine ioxaglate (Ionic)	Nausea, vomiting, hives, urticaria, flushing, facial oedema, wheezing, dyspnoea, laryngeal oedema, hypotension, death
Ring 1985 [15]	800 adults undergoing IVP	Patients with previous life-threatening contrast reaction excluded	1. Prednisolone 250 mg ivi, 5 minutes prior to contrast 2. Clemastin 0.03 mg/kg ivi, 5 minutes prior to contrast 3. Clemastin 0.03 mg/kg ivi + cimetidine 5 mg/kg vi, 5 minutes prior to contrast	100 ml meglumine amidotrizoate (ionic)	Flush, urticaria, angioedema, respiratory symptoms, vomiting, tachycardia, hypotension
Lasser 1987 [17]	6763 adults undergoing IVP or contrast enhanced CT	Patients with previous severe reaction excluded. Patients with general allergies, drug allergies and previous non life threatening reactions were included	1. Methylprednisolone 32 mg po two hours prior to contrast 2. Methylprednisolone 32 mg o the night before + two hours prior to contrast	Various ionic contrast agents	Grade 1: emesis, nausea, sneezing, vertigo Grade II: Hives, fever, hills, Grade III: Shock, bronchospasm, laryngospasm, laryngeal oedema, loss of consciousness, angioedema
Lasser 1994 [18]	1155 adults undergoing IVP or contrast enhanced CT	Patients with allergies including previous reactions to contrast were included	Methylprednisolone 32 mg po the night before and two hours prior to the contrast	Iohexol, Ioversol (non-ionic)	As per Lasser 1987