Which of the following signs indicates a need for medical follow-up during therapy with Sulfamethoxazole; Trimethoprim?

The indication of dark urine during therapy with Sulfamethoxazole; Trimethoprim suggests a potential issue that warrants medical follow-up. This can be a sign of several conditions, including hematuria (blood in the urine) or liver dysfunction, which may arise as side effects of the medication. Besides being a possible sign of dehydration or concentrated urine, dark urine may also indicate the presence of metabolites or other substances that should be evaluated further.

In contrast, improving symptoms after 2-3 days is generally a positive sign that the medication is effectively treating the infection. Light gastrointestinal upset may occur as a common side effect of many antibiotics and may not necessarily indicate a need for medical intervention unless it is severe or persistent. Mild headaches can also be a normal side effect but usually do not warrant follow-up unless they are severe or accompanied by other concerning symptoms. Thus, dark urine stands out as a sign that requires further medical evaluation during treatment with this antibiotic combination.