Who is "they"? If you find the 1 mg/pound on a reputable reference, then it should be okay. I don't remember how many mg is in one capsule but I wouldn't hesitate to give a full capsule twice a day for a dog 90 pounds. You may be able to go higher, but I like to start low and work up.
My dog is 90lbs an american blue bully pitbull has lil bumps all over his body comes and goes how much benadryl do i give him they say 1mg per pound is it true
yes Benedryl is safe for dogs as long as you are using the proper dosage. Just like with people it might make them sleepy so giving it at night time is a good idea. If you are giving him the same amount he has been taking then there's nothing to worry about.