Dog Developed Sudden Eye Irritation And Swollen Now What To Do?

Benadryl is supposed to be given at 1mg/pound, so make sure you gave him the right dosage. If he is having trouble breathing, then you should take him to the vet immediately.

I agree with you in that this is an allergic reaction to something he has come in contact with. Check his food, and your kitchen/bathroom to see if he got into contact with something new (cleaning supplies). See if there are any bite marks on him, as he could have been bitten by an insect that would also give an allergic reaction.

If Benadryl does not make the dog feel better in 12 hours, then you need to take him to a vet as soon after as possible.

YES I AGREE AND THINK I FOUND THE CULPRIT,, HE WAS PUT BACK ON cephalexin yesterday for an ear infect..he was put on these meds last week  for a lick wound and I had stopped them  as they caused him to throw up daily.. Vet put him back on it for the ear.. Woke up this today and HE  is fine..all swelling went down..took him to the vet and they agree it is the meds..so needless to say he will not being back on them again..will have to find another antibiotic that agrees with him.. And thank you ! :)