Lower respiratory (tract) infection or LTRI is a generic term for an acute infection of the trachea (windpipe), airways and lungs, which make up the lower respiratory system. LTRIs include bronchitis, croup and pneumonia. Although influenza (the flu) can involve the lower respiratory system, it is not considered among the group of illnesses referred to by the term "lower respiratory infection."

Lower respiratory infections are more common in the winter because people tend to stay indoors and share the same recirculated air (and germs). Symptoms of LTRIs vary depending on the type of infection, but often include nasal congestion, runny nose, cough, sore throat, fever and lethargy.

The best way to prevent LTRIs is to practice good hygiene, since they are usually spread by hands coming into contact with secretions from an infected person. This means a lot of hand-washing and minimal physical contact with the sick person, especially in a place where someone has an LTRI. Someone who has an LTRI should stay home from work or school to prevent spreading it. You can also get vaccinated against some respiratory infections, such as pneumonia and the flu.

Treatment for LTRIs includes rest, hydration and over-the-counter medications, such as antihistamines, antitussives, anti-inflammatories, expectorants and nasal steroids, depending on your symptoms. If you have an LTRI, steam inhalation, warm saline gargles and raising the head of your bed may help alleviate symptoms. While vitamin C, zinc salts and Echinacea are popular, there is no conclusive evidence that these will help you recover from your illness. Most respiratory infections will go away without any treatment, but special care should be taken if someone very young, very old, with a pre-existing lung condition or with a weakened immune system gets a respiratory infection because it can be dangerous to them.