If a patient on penicillin for 2 weeks reports a sore tongue, what is the most appropriate next step?

When a patient on penicillin reports a sore tongue after two weeks of treatment, the most appropriate next step is to conduct a fungal test. This is because one of the common side effects of prolonged antibiotic use, such as penicillin, is the disruption of normal flora in the mouth, which can lead to overgrowth of fungi, particularly Candida species. This can manifest as oral thrush, resulting in a sore, painful tongue.

A fungal test allows for the identification of any fungal involvement in the condition, which is crucial in guiding the appropriate treatment. If an overgrowth of Candida is confirmed, antifungal treatments can be initiated to alleviate the symptoms and resolve the underlying issue.

In contrast, other options, such as a cytology smear or prescribing additional antibiotics, would not address the likely fungal complication that arises from antibiotic use. Sending the patient to the emergency room may also be excessive in this context unless there are signs of a more serious condition, which are not indicated by the mere presence of a sore tongue after antibiotic treatment. The focus should rather be on confirming the cause of the symptoms with relevant testing.