A lower respiratory tract infection can affect the airways, such as with bronchitis, or the air sacs at the end of the airways, as in the case of pneumonia.
In this article, we look at the causes and symptoms of lower respiratory tract infections and discuss their treatments and prevention.
Symptoms of a less severe lower respiratory tract infection can include a dry cough, a low fever, and a runny nose.
Symptoms of lower respiratory tract infections vary and depend on the severity of the infection.
Less severe infections can have symptoms similar to the common cold, including:
In more severe infections, symptoms can include:
- a severe cough that may produce phlegm
- difficulty breathing
- a blue tint to the skin
- rapid breathing
- chest pain
Upper vs. lower respiratory tract infections
Lower respiratory tract infections differ from upper respiratory tract infections by the area of the respiratory tract they affect.
While lower respiratory tract infections involve the airways below the larynx, upper respiratory tract infections occur in the structures in the larynx or above.
People who have lower respiratory tract infections will experience coughing as the primary symptom.
People with upper respiratory tract infections will feel the symptoms mainly above the neck, such as sneezing, headaches, and sore throats. They may also experience body aches, especially if they have a fever.
Lower respiratory tract infections include:
Upper respiratory tract infections include the following:
Flu infections can affect both the upper and lower respiratory tracts.
Causes and risk factors
Tobacco smoke can lead to a lower respiratory tract infection.
Infections in the lower respiratory tract are primarily the result of:
- viruses, as with the flu or respiratory syncytial virus (RSV)
- bacteria, such as Streptococcus or Staphylococcus aureus
- fungal infections
- mycoplasma, which are neither viruses or bacteria but are small organisms with characteristics of both
In some cases, substances from the environment can irritate or cause inflammation in the airways or lungs, which can lead to an infection. These include:
- tobacco smoke
- vapors and fumes
- air pollution
Risk factors that make a person more likely to develop a lower respiratory tract infection include:
- a recent cold or flu
- a weakened immune system
- being more than 65 years old
- being under 5 years old
- recent surgery
A doctor will usually diagnose a lower respiratory infection during an exam and after discussing the symptoms a person has and how long they have been present.
During the exam, the doctor will listen to the person's chest and breathing through a stethoscope.
The doctor may order tests to help diagnose the problem, such as:
- pulse oximetry to find how much oxygen is in the blood
- chest X-rays to check for pneumonia
- blood tests to check for bacteria and viruses
- mucus samples to look for bacteria and viruses
Some lower respiratory tract infections go away without needing treatment. People can treat these less-severe viral infections at home with:
- over-the-counter medications for a cough or fever
- plenty of rest
- drinking plenty of fluids
In other cases, a doctor may prescribe additional treatment. This may include antibiotics for bacterial infections, or breathing treatments, such as an inhaler.
In some cases, a person may need to visit the hospital to receive IV fluids, antibiotics, or breathing support.
Very young children and infants may need more treatment than older children or healthy adults.
Doctors often monitor infants especially closely if they have a higher risk of severe infections, such as premature infants or infants with a congenital heart defect. In these cases, a doctor may be more like to recommend hospitalization.
Doctors can also recommend similar treatment for people of 65 years of age and above or those individuals with weakened immune systems.
Recovery time for a lower respiratory tract infection varies from person to person.
According to the American Lung Association, a healthy young adult can recover from a lower respiratory tract infection, such as pneumonia, in around 1 week. For older adults, it may take several weeks to make a full recovery.
Washing the hands frequently can help prevent lower respiratory tract infections.
A person can take many steps to prevent getting a lower respiratory tract infection, including:
- washing their hands frequently
- avoiding touching the face with unwashed hands
- staying away from people with respiratory symptoms
- cleaning and disinfecting surfaces regularly
- getting vaccines, such as the pneumococcal vaccine and MMR vaccine
- getting a flu shot every year
- avoiding known irritants, such as chemicals, fumes, and tobacco
Most lower respiratory tract infections are uncomplicated. However, when complications occur, they can be very serious.
Complications of lower respiratory tract infections can include:
- congestive heart failure
- respiratory failure
- respiratory arrest
- sepsis, which is a blood infection that can lead to organ shutdown
- lung abscesses
Most healthy people make a full recovery from uncomplicated lower respiratory tract infections. However, complications can have long-term effects.
People who are most at risk for complications include people with other health conditions, adults over 65 years of age and children under 5 years old. These groups can take steps to prevent lower respiratory infections and can consult a doctor if they develop symptoms.
Respiratory tract infections (RTIs), nHS
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