Cani take Benadryl (diphenhydramine) with loratadine?

Probably yes. Many people report their 'daily' non-sedating antihistamine in the am does not provide relief until next am. So, if no concerns for gu/heart/bp/med-conflict issues, then they often take a 'sedating' antihistamine at night for continued symptom relief and 'bonus' of sleep aid effect.