What is the litte brown pill with G103 on it?

The little brown pill marked with "G103" is identified as Diphenhydramine hydrochloride 25 mg, which is an over-the-counter antihistamine commonly used to relieve symptoms of Allergies, hay fever, and the common cold. It can also be used as a nighttime sleep aid due to its sedative properties. Always consult with a healthcare professional before using any medication to ensure it is appropriate for your situation.