What is white pill with DH30 on 1 side and G on other?

The white pill imprinted with "DH30" on one side and "G" on the other is identified as Diphenhydramine Hydrochloride 25 mg, an antihistamine commonly used to relieve symptoms of allergy, hay fever, and the common cold. It can also be used as a sleep aid due to its sedative properties. Always consult a healthcare professional or pharmacist for more information and guidance on usage.