An 82-year-old woman is admitted to the ED short stay ward

overnight for observation. She presented with a generalised urticarial rash

with lip swelling after eating her Christmas lunch at home with her family. She

was given adrenaline 0.3mg IM on arrival at 8pm. Prednisone 50mg was given 15

mins later together with promethazine oral.

She is normally well, lives alone and independent in all her

daily activities. She lives close to her children and grandchildren. She has no

cognitive impairment noted in her eMR. She is on aspirin 100mg daily and

lercandipine 10mg at night for her hypertension.

This morning, she is confused and unable to attend to her

toileting and has been incontinent. HR

90/min, BP 140/90 mm Hg, temp 37°C.

Her vital signs are normal.

What is the most likely cause of her symptoms?