OVERVIEW

What is pneumonia?

Pneumonia refers to inflammation of the lungs and is a common respiratory disease. It can be caused by microbial infections such as bacteria, viruses, fungi, or parasites, as well as by factors like radiation exposure or inhalation of foreign objects. Common symptoms include fever, cough, sputum production, and chest pain^[1-3].

Pneumonia caused by microbial infections is also called lung infection or infectious pneumonia, which can be treated with anti-infective therapies (including antibacterial, antiviral, or antiparasitic treatments). Other types of pneumonia require different treatments. Most cases of infectious pneumonia can be cured, but severe pneumonia may be life-threatening.

What are the types of pneumonia?

Classification by affected area: Lobar pneumonia, lobular pneumonia, interstitial pneumonia;

Classification by cause: Bacterial pneumonia, viral pneumonia, atypical pathogen pneumonia, fungal pneumonia, pneumonia caused by other pathogens, and pneumonia due to physical or chemical factors;

Classification by setting: Community-acquired pneumonia, hospital-acquired pneumonia^[1-3].

What is SARS?

Severe Acute Respiratory Syndrome (SARS) is a highly contagious pneumonia caused by the SARS coronavirus, which can lead to severe complications and even be life-threatening. SARS can affect people of any age. Main symptoms include fever (often above 38°C, possibly with chills), dry cough (occasionally with bloody sputum), and difficulty breathing, along with headaches, body aches, fatigue, and diarrhea. It can easily cause complications and endanger the patient's life.

SYMPTOMS

What are the common manifestations of pneumonia?

The clinical manifestations of pneumonia caused by different etiologies vary slightly, but the main symptoms include cough, sputum production, fever, chills, chest pain, and difficulty breathing.

Severely ill patients may also experience hypoxia, restlessness, respiratory failure, shock (syncope, hypotension, loss of consciousness), oliguria, and kidney failure^[1-3].

What complications may arise if pneumonia is not treated promptly?

If pneumonia is not treated in time, the following complications may occur:

• Lung abscess, empyema, or even pericarditis and meningitis;
• Bacteremia or septic shock;
• Persistent high fever, which may lead to febrile seizures or even coma;
• Respiratory failure, hypoxia, or neurological damage, resulting in drowsiness or coma.

What are the common complications of pneumonia?

• Pleural effusion: Caused by infection of the pleural cavity by pneumonia pathogens. Symptoms include fever, chest pain, chest tightness, difficulty breathing, cough, sputum production, loss of appetite, and fatigue.
• Sepsis: Occurs when pathogens invade the bloodstream, multiply, and produce toxins, leading to severe systemic inflammatory response syndrome, which can cause multiple organ failure.
• Purulent meningitis: If untreated, bacteria may enter brain cells, causing meningitis. Symptoms include fever, headache, vomiting, and convulsions.
• Septic shock: Clinical manifestations include hypotension, difficulty breathing, oliguria, and cyanosis (bluish discoloration of lips or fingertips)^[1-3].

Can pneumonia leave sequelae?

Most cases of ordinary pneumonia, if treated promptly, do not leave sequelae. However, some may show linear shadows or uneven pleural thickening on chest X-rays or CT scans. Patients with a history of tuberculosis may develop calcifications in the lungs, but these do not affect daily life or lifespan.

If pneumonia is severe and complications such as meningitis or pericarditis occur, sequelae like headaches, dizziness, palpitations, or chest pain may persist.

Can pneumonia develop into lung cancer?

No. However, if pneumonia recurs repeatedly in a specific area of the lung, lung cancer should be suspected.

This is not because recurrent pneumonia causes lung cancer, but rather because lung cancer may block a bronchus, making that area prone to repeated infections. This type of pneumonia is called "obstructive pneumonia," and its response to antibiotic treatment is usually poor.

CAUSES

How does pneumonia occur?

Different types of pneumonia have different causes. For example:

• Infectious pneumonia: Pathogens (viruses, bacteria, fungi, mycoplasma, chlamydia, parasites, etc.) can enter the bronchi and lungs through the respiratory tract or bloodstream. If the body's immunity is low or the pathogen is highly virulent, the body may fail to clear these pathogens in time, leading to pneumonia.
• Aspiration pneumonia: This is lung inflammation caused by accidental inhalation. Common situations prone to aspiration include alcohol intoxication, epileptic seizures, anesthesia, stroke, gastroesophageal reflux, and foreign body inhalation.
• Radiation pneumonia: This occurs due to lung tissue damage caused by radiation therapy for malignant tumors. Cancers that commonly lead to radiation pneumonia include lung cancer, breast cancer, and esophageal cancer.
• Others: Autoimmune diseases can also cause lung inflammation due to immune system disorders. Certain medications (e.g., amiodarone) may induce interstitial pneumonia. Long-term inhalation of asbestos dust can cause chronic pneumonia, manifesting as pulmonary fibrosis, etc.^[1-3].

Is pneumonia contagious?

Pneumonia caused by microorganisms (infectious pneumonia) may be contagious.

Common viral, bacterial, fungal, or mycoplasma pneumonia is not highly contagious and does not cause large-scale outbreaks. Only individuals with weakened immunity (e.g., young children, the elderly, or those with chronic illnesses) may develop pneumonia if they inhale pathogen-containing droplets from infected individuals.

However, pneumonia caused by certain highly contagious pathogens (e.g., SARS, anthrax bacillus, plague bacillus, or tuberculosis bacteria) can spread rapidly through inhalation of infected droplets or contact with contaminated objects, potentially leading to widespread transmission.

Who is more susceptible to pneumonia?

• Immunocompromised individuals: Such as young children, the elderly, chronically ill patients, HIV/AIDS patients, cancer patients undergoing radiotherapy/chemotherapy, organ transplant recipients on immunosuppressants, or post-splenectomy patients. Their weakened immunity increases infection risks.
• Smokers: Smoke and its harmful components can damage lung tissue.
• Those who vomit or aspirate after alcohol intoxication: Foreign substances entering the lungs can trigger inflammation.
• Occupational exposure to dust: Long-term dust inhalation irritates lung tissue, causing inflammation.
• Bedridden individuals: Prone to hypostatic pneumonia.

DIAGNOSIS

When to Seek Medical Attention Promptly?

Seek medical attention promptly if the following conditions occur:

• Fever, cough, or sputum production persists for three days without improvement and shows worsening trends;
• The condition continues to deteriorate, with persistent high fever, persistent cough, purulent sputum, difficulty breathing, chest pain, or hemoptysis;
• Extrapulmonary symptoms such as abdominal distension, nausea, vomiting, loss of appetite, headache, fatigue, irritability, or drowsiness appear;
• Critical conditions like hypoxia, cyanosis (bluish discoloration of lips or fingertips), or shock occur.

How Is Pneumonia Diagnosed? What Tests Are Needed?

When symptoms like cough, sputum production, fever, or chest pain appear, pneumonia should be suspected, and medical attention should be sought promptly. The doctor will conduct a thorough physical examination (including temperature measurement and lung auscultation) and diagnose pneumonia based on blood tests and imaging results. Common tests include:

• Complete Blood Count (CBC): One of the primary diagnostic tools for pneumonia. It assesses bacterial infection and severity through white blood cell count, neutrophil count, C-reactive protein (CRP), and procalcitonin levels, and can dynamically reflect treatment efficacy.
• Arterial Blood Gas Analysis: Evaluates respiratory function abnormalities in pneumonia patients.
• Pulmonary Function Tests: Clinically significant for early diagnosis, treatment monitoring, and prognosis assessment.
• Chest X-ray: Determines the location and severity of lesions and is crucial for follow-up and treatment evaluation.
• Chest CT: Provides detailed views of lung tissue microstructure, useful for detecting lesions not identifiable by X-ray or routine tests.
• Pathogen Testing: Includes sputum smear and culture, the most common methods for diagnosing bacterial pneumonia types. Sensitivity and specificity are limited, so samples are usually collected before antibiotic use to guide targeted treatment^[1-3].

What Is the Purpose of a CBC in Pneumonia?

• Helps doctors preliminarily determine the cause of pneumonia and decide on treatment.
• In bacterial pneumonia, white blood cell and neutrophil counts typically increase significantly, with elevated neutrophil ratios.
• In Mycoplasma or Chlamydia pneumonia, white blood cell and neutrophil counts are normal or slightly elevated.
• In viral pneumonia, white blood cell counts may be normal, slightly elevated, or reduced, with increased lymphocyte ratios.

Note: Pathogen identification (bacterial or viral) cannot rely solely on CBC results; it must be combined with symptoms and clinical findings.

TREATMENT

How to treat pneumonia?

General treatment:

Rest in bed as much as possible during the illness and increase fluid intake. Ensure adequate intake of protein, calories, and vitamins.

Symptomatic and supportive treatment:

• Cough relief and expectoration: For dry cough, antitussive drugs such as dextromethorphan or codeine phosphate may be used as prescribed. For excessive or purulent sputum, expectorants like ambroxol hydrochloride or acetylcysteine can be taken orally or administered via nebulization. Strictly follow medical advice and avoid self-medication.
• Fever reduction: For high fever, physical cooling methods such as ice packs or cooling patches can be used first. If the fever persists, antipyretic drugs like ibuprofen may be taken as prescribed, but be cautious of potential risks from overuse (e.g., excessive sweating, electrolyte imbalance, increased risk of gastrointestinal bleeding)^[1-3].

Anti-infective treatment:

• Antibacterial drugs: These are the main treatment for bacterial pneumonia. Common antibiotics include penicillins, cephalosporins, quinolones, macrolides, sulfonamides, and antifungal drugs. Strictly follow medical advice to avoid antibiotic resistance.
• Antiviral drugs: For viral pneumonia, commonly used antivirals include ribavirin, acyclovir, ganciclovir, and oseltamivir^[1-3].

Which department should you visit for pneumonia?

Respiratory Medicine, Infectious Diseases, or Emergency Department.

How to treat radiation pneumonia?

Radiation pneumonia is an adverse effect of radiotherapy, often seen in patients with lung cancer, breast cancer, esophageal cancer, or malignant lymphoma. Mild cases may resolve on their own, while severe cases can lead to pulmonary fibrosis, significantly impairing respiratory function. If radiation pneumonia is detected, radiotherapy should be stopped immediately. Severe cases require early treatment with glucocorticoids.

Is antibacterial treatment always necessary for infectious pneumonia?

Not necessarily. Infectious pneumonia can be caused by viruses, bacteria, fungi, or other pathogens, and not all cases require antibacterial drugs. For example, antibiotics are ineffective against viral infections.

What to do if a cough persists after pneumonia recovery?

Some patients may experience persistent dry cough or small amounts of white mucus for 3–8 weeks or longer after fever subsides and symptoms improve, known as "post-infection cough." This may be due to damaged respiratory mucosa and increased sensitivity after infection. Since the pathogen has been cleared, antibiotics are ineffective. Under medical guidance, antitussives or antihistamines like dextromethorphan, codeine, or chlorpheniramine may be used^[2].

DIET & LIFESTYLE

How should pneumonia patients adjust their diet?

To promote recovery from pneumonia, the diet should ensure adequate intake of calories, protein, and vitamins. Staples like rice and wheat provide calories, while eggs, fish, chicken, and dairy products are rich in easily digestible protein. Fresh vegetables and fruits are the main sources of vitamins.

Spicy and irritating foods should be consumed in moderation to avoid aggravating throat discomfort. Fried and greasy foods should be minimized as they are hard to digest.
Avoid alcohol during treatment^[3].

What should pneumonia patients pay attention to in daily life?

• Maintain regular meals, ensure a balanced diet, and quit smoking and alcohol.
• Get adequate rest and avoid overexertion or intense exercise.
• Choose moderate-intensity physical activities (e.g., jogging, cycling) based on personal condition, avoiding strenuous exercise.
• Ensure indoor ventilation and maintain appropriate humidity (50%-60%). Low humidity may trigger coughing, while high humidity fosters bacterial growth.
• Drink plenty of water, as fever and sweating lead to fluid loss. Increased water intake and urination help eliminate metabolic waste faster, aiding recovery.
• Maintain good hygiene: wash hands frequently, wear masks, cover mouth and nose with tissues or elbow when coughing/sneezing, avoid crowded places, and prevent spreading the infection.

PREVENTION

How to Prevent Pneumonia?

• Develop good hygiene habits, wash hands frequently with soap and running water.
• Vulnerable groups, the elderly, and people with chronic diseases (such as hypertension, diabetes, etc.) can get vaccinated with pneumonia vaccines (13-valent and 23-valent pneumococcal vaccines) and flu vaccines. Search or click to learn about "pneumonia vaccines" and "flu vaccines" to understand suitable groups and vaccination timing.
• Exercise regularly to boost immunity.
• Avoid pneumonia triggers such as getting caught in the rain, fatigue, or excessive alcohol consumption.
• The elderly, children, and those with weak immunity should avoid contact with people who have colds or pneumonia, minimize visits to crowded or enclosed public places, and wear masks in densely populated areas.
• Ventilate rooms regularly. In colder weather, ventilate for about half an hour daily while ensuring proper clothing.
• Bedridden individuals should change positions frequently to prevent hypostatic pneumonia.