My 12 year old son had a severe allergic reaction which lasted for just over 48 hours, despite 4 hourly doses of Piriton, even throughout the night. He was covered in inflamed, itchy hives, his lips swelled, his face was swollen & he was mildly short of breath. He also had mild diarrhoea, a headache & a sore throat (possible hives in his throat, as he certainly had them inside his mouth.) He was at school when the reaction started & we do not know what caused it. He had finished a strong, 7 day course of Amoxicillan 36 hours prior to the reaction. He visited the dentist for a check up 24 hours before the reaction. She used Phosphoric acid on his teeth during the examination & wore rubber gloves. I don't believe that he ate anything out of the ordinary before his reaction. Is it possible that it could have been the antibiotics or the dentists visit which caused such a violent reaction, or was it too long after for either of these to be relevant?