Which systemic sign of illness indicates the need for further evaluation in cellulitis?

Tachycardia is a systemic sign of illness that can indicate that cellulitis has progressed or that the patient is experiencing a more systemic response to infection. When a patient has tachycardia, it often suggests that the body is reacting to an infection, potentially indicating that the infection may be severe or that there is an associated systemic inflammatory response. This heightened heart rate can serve as a vital sign that warrants further evaluation, as it may point to more serious complications or an extension of the infection.

In cases of cellulitis, while local signs such as redness and warmth are typically observed, the presence of systemic signs like tachycardia makes it critical to assess the patient for potential systemic involvement, including sepsis or the need for hospitalization and intravenous antibiotics. Thus, finding tachycardia in a patient with cellulitis suggests that the condition may not be as straightforward as it appears, and this necessitates further evaluation to address the patient's overall status and treatment needs.