We often see allergies in cats and dogs, with irritation being the most common symptom. Side effects include skin and ear infections. Therefore, you should consult your vet as soon as your pet starts scratching and can't seem to stop.
So what might they be allergic to? There are so many allergens, like dust, out there in the environment. An allergy to pollen, which is seasonal, is quite common. If that is the case, we can reduce exposure but it can't be avoided entirely. However, if your dog or cat has a food allergy, that is something that is easier to control. Your vet will perform a few tests to detect the allergen: they will choose a protein that your pet has never eaten, continuing in this manner in a process of elimination. Obviously, it is crucial, during this test period, not to change your pet's diet without first discussing it with your vet.
Living with a dog, cat with allergies means facing this reality. Your vet can suggest an approach to control the symptoms.