I'm a 51 yr. old female, i want to know can i take a pain reliever p.m. after i have taken a loratadine tab 10 mg?

PM: Benadryl (diphenhydramine) life is about 20 hrs. Although Loratadine is a more specific H-1blocker, may add a bit but should be OK.

Probably ok: You may be doing double duty on the antihistamine, so if you have a non-"pm" pain reliever that might be better, but most likely you'll be fine if you take them both. There's no absolute contraindication to combining them.