Pneumonia is a lung infection that causes cough, fever, and difficulty breathing. It can affect one or both lungs, and may cause serious illness in young children, people over age 65, and people with other health problems.
After starting treatment for pneumonia, symptoms should start to improve.
How long pneumonia lasts depends on its severity. In general:
- In 1 week, high temperature should go away
- In 4 weeks, chest pain and mucus production should decrease significantly
- In 6 weeks, cough and breathlessness should have markedly decreased
- By 3 months, most symptoms should have gone away though fatigue may still persist
- By 6 months, most people will be fully recovered
Bacterial pneumonia is usually considered contagious until you have taken antibiotics for 24 to 48 hours. Viral pneumonia remains contagious as long as symptoms are present.
What Are Symptoms of Pneumonia?
Symptoms of pneumonia include:
- Cough
- May produce phlegm or mucus that may be yellow, greenish, or bloody
- Sharp pain on inhalation or when coughing
- Shortness of breath
- Difficulty breathing
- Fever
- Chills
- Fatigue
- Loss of energy
- Shaking
- Sweating
- Fast heartbeat
- Loss of appetite
- Nausea and vomiting (more common in young children)
- Confusion (more common in older people)
What Causes Pneumonia?
Common causes of pneumonia include bacteria, viruses, and fungi.
Typical bacteria that cause pneumonia include:
- S. pneumoniae (most common bacterial cause)
- Haemophilus influenzae
- Moraxella catarrhalis
- Staphylococcus aureus
- Group A streptococci
- Aerobic gram-negative bacteria (e.g., Enterobacteriaceae such as Klebsiella spp or Escherichia coli)
- Microaerophilic bacteria and anaerobes (associated with aspiration)
Atypical bacteria that cause pneumonia include:
Respiratory viruses that cause pneumonia include:
- Influenza (“flu”) viruses
- Coronaviruses (e.g., COVID-19, Middle East respiratory syndrome coronavirus)
- Rhinoviruses
- Adenoviruses
- Parainfluenza viruses
- Respiratory syncytial virus (RSV)
- Human metapneumovirus
- Human bocaviruses
How Is Pneumonia Diagnosed?
Pneumonia is diagnosed with a patient history and physical examination, in which a doctor will check the lungs with a stethoscope to listen for crackling, bubbling, and rumbling sounds on inhalation.
Tests to confirm pneumonia include:
- Blood tests
- Influenza
- COVID-19
- Polymerase chain reaction (PCR)
- Sputum test on a sample of mucus (sputum) taken after a deep cough
- Pulse oximetry to measure blood oxygen levels
- Arterial blood gas test
- Chest X-ray
- Urinary antigen testing for S. pneumoniae
- Computerized tomography (CT) scan of the chest
- Pleural fluid culture: a small amount of fluid is removed from tissues surrounding the lung
- Bronchoscopy: a tube with a light on the end is used to look into the airways
What Is the Treatment for Pneumonia?
Treatment for pneumonia depends on the type of pneumonia, how sick the patient is, the patient’s age, and if other underlying medical conditions are present.
Mild cases of pneumonia may resolve on their own and all that is needed is to manage symptoms along with adequate rest. Home treatment for pneumonia includes:
- Getting plenty of rest
- Drinking adequate fluids
- Warm beverages may help open airways
- Fever reducers
- Steamy baths or showers or use of a humidifier can help open airways
- Don’t smoke and avoid secondhand smoke or any other lung irritants
- Check with your doctor before taking cough medicines because coughing helps the body work to rid itself of infection
If medicines are needed, medications used to treat pneumonia include:
- Antibiotics, if the cause is bacterial
- Antivirals, if the cause is viral
In severe cases of pneumonia, hospitalization may be needed, and treatment may include:
- Intravenous (IV) fluids
- Breathing treatments
- Intravenous antibiotics
- Oxygen therapy
From 
Featured Centers
Health Solutions From Our Sponsors
https://www.uptodate.com/contents/pneumonia-in-adults-the-basics?search=pneumonia%20stages&source=search_result&selectedTitle=3~150&usage_type=default&display_rank=3
https://www.uptodate.com/contents/overview-of-community-acquired-pneumonia-in-adults?search=pneumonia%20causes&source=search_result&selectedTitle=3~150&usage_type=default&display_rank=3#H3873548286
https://www.lung.org/lung-health-diseases/lung-disease-lookup/pneumonia?referrer=https://www.google.com/
https://www.nhs.uk/conditions/pneumonia/treatment/#:~:text=6%20weeks%20%E2%80%93%20cough%20and%20breathlessness,will%20feel%20back%20to%20normal