Usually, a bout of the common cold is not a major concern. You take a day or two off from work, treat your symptoms with pain relievers or cough syrup, and your body heals itself in time. Even the flu, though it causes more serious symptoms, is not usually overly worrisome in adults. However, there are times when your cold or flu may turn into something more serious, like pneumonia or bronchitis. These conditions do require urgent care, so it's important that you know what symptoms indicate a visit to the doctor is in order.

Bloody Mucous

If you start coughing up mucous with blood in it, then you need to head to your doctor's office or an urgent care center. This may indicate damage to your lungs or the bronchi, which are the airways leading into your lungs. Treatment is important to ensure you do not lose too much blood, and also to ensure the infection does not become any worse.

High Fever

A fever of 100 or 101 degrees is quite common with the flu, and as long as it does not last more than a day or two, you do not need to be too concerned. However, if your fever persists even after you take a fever-reducing medication like ibuprofen, or if you have a fever exceeding 104 degrees F, you should see the doctor. A persistent, high fever can cause brain damage if left untreated, and the fever may indicate that your illness has progressed towards pneumonia, which can be fatal if you do not receive appropriate care.

A High-Pitched or Painful Cough

It's normal to have a bit of a cough with the common cold or flu. But if your cough develops a strange, high-pitched tone, you should seek medical care since this might mean you have a bacterial infection called pertussis. Pertussis is not overly serious in adults, but it is very contagious and can be deadly in children, so it's important to be treated with antibiotics so you don't pass on the infection.

Ongoing Sore Throat

Usually when a sore throat is due to a cold, it goes away in a couple of days and is not so serious that it keeps you from eating. If your sore throat makes it nearly impossible to eat, or if it lasts for more than a couple of days, you may have strep throat, a bacterial infection that requires antibiotic treatment.