What is a yellow pill with 753 on it?

A yellow pill with the imprint "753" is identified as Diphenhydramine Hydrochloride 25 mg, which is an over-the-counter antihistamine used to relieve symptoms of allergy, hay fever, and the common cold, such as rash, itching, watery eyes, itchy eyes/nose/throat, cough, runny nose, and sneezing. It is also commonly used as a sleep aid due to its sedative properties. Always use medications as directed and consult a healthcare provider if you have any concerns.