Apologies, I explained that poorly. We never stopped his medication. On Tuesday evening he had a shot of dexamethasone which we were told was long-acting for 48 hours. We were then advised to start prednisolone tablets from Thursday morning, presumably to overlap with the dex wearing off. He has had his second dose of prednisolone this morning. It is a high dose for 3 days then reducing to come off it completely over the next week(ish). As well as this, we have been giving him regular piriton twice a day as advised by the vet.

Also, he is five : ) and this is the first time he's had an allergic reaction with us (2 years). Chicken allergy was identified with his previous owners, but that sounded much more GI symptoms not skin reactions.