My vet said the two most important things to get them in right away is eyes and breathing so i would go if having breathing and the eye prob.
There are other antihistamines that you can try as well as benedryl. I use a 1/4 tablet of a 25mg for my girl yorkie and she is 6lbs but the benedryl did not help with hers as she has atopic dermatitis and severe itching.
I have only had the swollen eye one time as she itched it on carpet and had a bad allergic reaction and they gave her eye drops and a dexamothesone shot for itching.
Allergies are no fun and i have been working with dermatologist and holistic vets as well as regular vet for 2 1/2 years and still not completely there but better
