I recommend some for your own reference: Yangshengtang Pharmacy, Baijitang Pharmacy, Happy People Pharmacy, People's Pharmacy, etc. I know these stores are all in Chaoyang District, but your neighborhood is not clear.
Tongrentang is a time-honored brand in Beijing, which is absolutely reliable. There is nothing to say. In fact, as long as it is a big pharmacy, it is all correct. If it's a big deal, go to a few more and compare yourself.