Hypoallergenic Food ?

It's impossible to say since you didn't tell us what specific ingredients your dog is allergic to. If your dog is allergic to lamb, oats, potato, sweet potato, alfalfa, or peas, it will not help.

Less than 10% of allergy symptoms are food based. It is far more likely your dog is allergic to dust, mold, fragrance, cleaning products, natural fibers, your Christmas tree, etc.

To rule out a food allergy you need to feed a limited ingredient diet. This means one meat your dog has never eaten, and a single carb your dog has never eaten. No other ingredients. Something like Natures Variety Limited Ingredient Turkey. You must also stop giving any treats or things to chew on. After 2-3 months on this diet your dog will either improve (confirming a food allergy), or not improve (confirming an environmental allergy).

Other possibilities could be improper bathing, frequent bathing, or flea & tick medications. Your vet can do an allergy test, which will tell you what your dog is allergic to and take all the guess work out of it.

My dog is on Purina Veterinary Diets HA Hypoallergenic. He has been on it for three years now. He is so much happier. It's expensive, but worth every penny. It is the only food I could find that actually stopped his constant itching. Before switching to this food I tried dozens of others, and no other food worked. It makes our life so much easier! You can ask your vet for a prescription for this food. I've tried all those grain-free kibbles, raw diets, etc. Nothing worked. In fact, I think a lot of those grain-free kibbles made him worse. Purina HA is a miracle food for my boy!

You could always talk to your vet about a prescription food you can usually buy from your vet's office. Science diet manufactures a food called Z/D that is especially made for dogs with food allergies.