How can you tell the difference between a cold & sinus infection? at what point would i need antibiotics (instead of just letting it run it's course)?

URIs: I use the following guidelines in my practice: antibiotics are given if the illness is increasing in severity, if a fever is present, if the illness has persisted for more than one week, and then if the patient is severely ill (by observation). If there is no fever, or other signs of significant illness and the patient is stable we talk about being patient and watching the course of the illness.