Most adults and older children have several respiratory infections each year. Respiratory problems can be as minor as the common cold or as serious as pneumonia. They may affect the upper respiratory system (nose, ears, sinuses, and throat) or the lower bronchial tubes and lungs. See an illustration of the respiratory system.

Upper respiratory system

The upper respiratory system includes the nose, ears, sinuses, and throat. When you have an upper respiratory infection you may feel uncomfortable, have a stuffy nose, and sound very congested. Other symptoms of an upper respiratory infection include:

• Facial pain or pressure.
• A runny or stuffy nose, which may lead to blockage of the nasal passages and cause you to breathe through your mouth.
• A sore throat.
• Irritability, restlessness, poor appetite, and decreased activity level.
• Coughing, especially when lying down.
• Fever that occurs suddenly and may reach 103 F or higher.

Lower respiratory system

The lower respiratory system includes the bronchial tubes and lungs. Respiratory problems are less common in the lower respiratory system than upper respiratory system.

The symptoms of a lower respiratory (bronchial tubes and lungs) problem usually are more severe than symptoms of an upper respiratory (ears, nose, sinuses, and throat) problem.

Symptoms of lower respiratory system infections include:

• Cough, which continues throughout the day and night, often producing green, yellow, brown, or gray mucus (sputum) from the lungs.
• Fever, which may be high with some lower respiratory system infections, such as pneumonia.
• Difficulty breathing. You may notice:
  • Shortness of breath.
  • Grunting, which is heard during the breathing out (exhaling) phase of breathing.
  • Wheezing.
  • Flaring the nostrils and using the neck, chest, and abdominal muscles to breathe, causing a "sucking in" between or under the ribs (retractions).
• Chest pain with exertion or when you take a deep breath.

Respiratory problems may have many causes.

Viral infections

Viral infections are the most common cause of upper respiratory symptoms. Symptoms of a viral illness often come on quickly (over hours to a day or two) without prior illness. Common viral illnesses include colds and influenza (flu).

• Colds are minor upper respiratory illnesses that usually go away without treatment. Symptoms may include cough, mild sore throat, nasal congestion, runny nose or sneezing, and occasionally a fever of 101 F or lower.
• Influenza (flu) symptoms are usually more severe than a cold. The key symptoms in adults are fever, often 104 F or higher, and body aches. Headache, eye pain, muscle aches, and cough are also common. For more information, see the topic Influenza.

Antibiotics are not used to treat viral illnesses and do not alter the course of viral infections. Unnecessary use of an antibiotic exposes you to the risks of an allergic reaction and antibiotic side effects, such as nausea, vomiting, diarrhea, rashes, and yeast infections. Antibiotics also may kill beneficial bacteria and encourage the development of dangerous antibiotic-resistant bacteria.