I don’t think there is any general size you can go by, every store and manufacturer seems to use a different standard.
For pants, it may be the same as dresses or it might be different, depending on whether your bust-to-hip ratio is the same as the manufacturer’s standard or not.
An online shopping website should have a size chart somewhere on the site with a table of actual measurements showing how the measurements correspond to their sizes. Also, if you already have some clothing from that brand, you can use it as a guide.
The side effects of allergy medications keep some people from using them. Natural remedies can be a great alternative, but some are more effective than others.