My (Max's) ophthalmologist talked to me about it since she frequently works with the local allergist and said that for environmental allergies it works fairly well, not so much for food allergies. So the question of efficacy also depends on knowing what allergies you're dealing with. Since none of this occurs in a vacuum, you may need to re-evaluate foods, environment and other potential allergens. For Max, the itchies were largely caused by foods. Knowing that, and thanks to our local independent pet store who armed us with samples, we were able to find a food to feed and know what foods to avoid which trigger the itchies. Also, do you know why the ears are infected? Yeast? Bacteria? Are you on a good probiotic? Our experience was that the itchies led to the sores which got infected and the circle just kept spinning out of control. Clean up the sores to stop the spiral then find the source of the itching. If all your vet is doing (not saying they are), is addressing the surface symptoms but not the underlying cause then you're in for a never ending cycle of suck.
Max "the ninja"-American Cocker Spaniel G-day 3/2009
Charlie "the middle child"- Orange Tabby G-day 7/2005
Sadie - Grey Tabby 9/1996-8/4/2012 RIP