What is a White round pill with 5325 on one side and RP on the other?

The pill marked with "5325" on one side and "RP" on the other is identified as Diphenhydramine hydrochloride 25 mg, which is an antihistamine commonly used for allergy relief, cold symptoms, and as a sleep aid. Diphenhydramine can cause drowsiness, so it is often taken at bedtime or when individuals need relief from allergy symptoms. Always consult a healthcare professional before taking any medication.