A 25-year-old man has pain in the left side of his mouth with fever and pus present. What is the most likely diagnosis?

In this scenario, the symptoms presented—a 25-year-old man with pain in the left side of the mouth, accompanied by fever and the presence of pus—strongly indicate a left submandibular gland infection, often referred to as sialadenitis or a submandibular abscess.

The pain localized to the left side of the mouth suggests involvement of the structures on that side, which can include the submandibular gland. The presence of fever and pus is a significant indication of an infection, and submandibular gland infections are commonly associated with these symptoms due to bacterial obstruction or ductal issues that can lead to pus formation.

Other conditions may present with similar symptoms, but the combination of localized pain, fever, and pus attributes a higher likelihood to an infection in the submandibular region.

Acute sinusitis typically manifests with nasal congestion, facial pressure, and possibly dental pain but is less likely to present with pus directly in the mouth and fever targeted in that manner. A dental abscess, while also a valid consideration, would normally present with specific tooth-related pain and swelling localized to the gum or tooth, rather than generalized pain in the mouth. Throat infections usually lead to symptoms like sore throat and