I don't have a bad anxiety about going into such stores, basically I can do it if I have to but I really really hate the experience and it certainly can affect my mood ( never in a good way). These places are so far away from what nature intended and I personally find that the further away from nature I am the more likely I am to be anxious. In these stores we that we are bombarded with artificial lighting, plastic petri chemical based items to buy everywhere and marketing ploys to get us to be brainwashed and buy this and that. Not to mentioned the often crowded atmosphere and maze of isles that have to be navigated in order to find what we needed/wanted to buy in the first place.
My advice, is that if the item required can't be sourced elsewhere then visit these stores early in the day, or late at night before closing when they are the least busy, this way at least you won't have the added extra stress of crowds and long waits at the registers. Go in with a clear focus of what you need and ask the shop assistant when you enter for directions so you spend less time looking for it. Basically get in and out as fast as you can...there are much nicer places to be spending precious time, anxiety or no anxiety!