Pneumonia: symptoms, causes, diagnosis and treatment

By Cristiano Antonino Last updated Jun 7, 2023

Pneumonia is inflammation of one or both lungs that is associated with an infection. Here’s everything you need to know about this disease

Coughing up phlegm or pus, fever, chills, and difficulty breathing? These could be symptoms of pneumonia, an inflammation of one or both lungs.

A variety of organisms, including bacteria, viruses, and fungi, can cause this condition, which can vary in severity from case to case.

It is typically more serious for infants and toddlers, people over the age of 65, and people with comorbidities and reduced immunity.

Symptoms of pneumonia

The signs and symptoms of pneumonia range from mild to severe, depending on the factors causing the infection, the age, and general health of the patient:

chest pain when breathing or coughing;
confusion and/or poor mental clarity;
cough, often oily with the presence of phlegm;
difficulty breathing;
high fever (especially in adults over 65 and people with weak immune systems);
sweating and shivering;
nausea, vomiting, or diarrhea;
shortness of breath.

Infants and children may be vomiting, have a fever and cough, appear restless or tired and without energy, or even have difficulty breathing and eating: symptoms that do not always immediately suggest pneumonia.

The causes of pneumonia

Many microorganisms can cause pneumonia.

Most frequently, the culprits are bacteria and viruses present in the air breathed.

The immune system usually prevents these germs from infecting the lungs, but sometimes it can happen that the defenses do not work properly and that the “enemies” take over.

The disease is classified according to the types of germs that cause it and where it was contracted.

Community-acquired pneumonia

Community-acquired pneumonia is the most common type of pneumonia.

It occurs outside of hospitals or other health care settings.

It can be caused by:

Streptococcus pneumoniae, a bacterium that is very frequently the cause of pneumonia. It can affect part of the lung, a condition called lobar pneumonia;
bacteria-like organisms, such as Mycoplasma pneumoniae. It typically triggers milder symptoms than those of other types of pneumonia;
fungi, which cause the disease mainly in people who have inhaled large quantities of them and in people with chronic health problems or weakened immune systems;
viruses, including the one responsible for COVID-19. Some of the viruses that cause colds and flu can trigger pneumonia. Viruses are the most common cause of pneumonia in children under the age of 5. Viral pneumonia is usually mild, but in some cases it can become very serious.

Hospital stay pneumonia

Some people get pneumonia during a hospital stay with another illness.

Hospital-acquired pneumonia can be serious because the bacteria that cause it may be more resistant to antibiotics and because the people who get it are already ill.

Patients using breathing machines (ventilators), often used in intensive care units, are at increased risk of contracting this type of pneumonia.

Healthcare acquired pneumonia

It is a bacterial infection that occurs in people who live in long-term care facilities or who receive care in outpatient clinics, including kidney dialysis centers.

Like hospital-acquired pneumonia, healthcare-acquired pneumonia can be caused by bacteria that are more resistant to antibiotics and therefore more aggressive.

Aspiration pneumonia

The aspiration form occurs when food, drink, vomit, or saliva is inhaled into the lungs.

Aspiration is more likely if something is disturbing the normal cough reflex, such as a brain injury or swallowing problem, or excessive alcohol or drug use.

Pneumonia, the risk factors

Pneumonia can affect anyone, but the two age groups most at risk are: children two years of age and younger and people 65 years of age and older.

Other risk factors include:

Being hospitalized.
Chronic cardiorespiratory disease: You are more likely to get pneumonia if you have asthma, chronic obstructive pulmonary disease (COPD), or heart disease;
weakened or suppressed immune system, for example from HIV/AIDS, an organ transplant or long-term chemotherapy/steroid treatment.

When to see a doctor

If you have difficulty breathing, chest pain, persistent fever equal to or higher than 39 °C, persistent cough, especially if accompanied by phlegm or pus, it is better to contact your doctor.

In particular, you should seek a consultation if you belong to one of these high-risk groups:

adults over the age of 65
children under the age of two;
people with a poor underlying health condition or a weakened immune system;
people who are undergoing chemotherapy treatment or are taking medicines that suppress the immune system;
elderly people and people with heart failure or chronic lung problems, where pneumonia can quickly become a life-threatening condition.

Treatments for pneumonia

Treatment for pneumonia consists of curing the infection and preventing complications.

Although most symptoms subside within a few days or weeks, the tired feeling can persist for a month or more.

The specific treatments depend on the type and severity of the pneumonia, your age, and your overall health.

Medicines used to treat bacterial pneumonia are often:

Antibiotics (in the case of viral pneumonia it would not be necessary to use them unless a bacterial superinfection occurs). It may take some time to identify the type of bacteria causing pneumonia and to choose the best antibiotic to treat it. If your symptoms don’t improve, your doctor may recommend a different antibiotic;
cough medicines, which help to calm the cough in order to allow the patient to be able to rest. Because coughing helps loosen and move fluid from the lungs, it’s a good idea not to eliminate it completely. It is advisable not to use too high dosages;
fever reducers/painkillers, to be taken as needed. These include drugs such as aspirin, ibuprofen and acetaminophen.

It’s also helpful to rest as much as possible and drink plenty of water to stay hydrated.

When is hospitalization needed?

You may need hospitalization in people:

over 65 years old;
in case of mental confusion
in case of signs of haemodynamic instability (low blood pressure, heart rate alterations, presence of pallor and/or blue discoloration of the mucous membranes “cyanosis”)
rapid breathing (30 breaths or more per minute)

Children can be hospitalized if:

they are less than two months old;
are lethargic or excessively sleepy;
have difficulty breathing;

The complications

Even with treatments, some people with pneumonia, especially those in high-risk groups, can experience complications, including:

bacteria in the blood (bacteraemia). Bacteria that enter the bloodstream from the lungs can spread the infection to other organs, potentially causing organ failure;
If the pneumonia is severe or the patient has underlying chronic lung disease they may have trouble breathing in enough oxygen. In these cases, you may need to stay in hospital and use a respirator (ventilator) while the lung heals;
accumulation of fluid around the lungs (pleural effusion). Pneumonia can cause fluid to build up in the thin space between the layers of tissue lining the lungs and the chest cavity (pleura). If the fluid becomes infected, it may need to be drained through a chest tube or removed with surgery;
lung abscess. An abscess occurs when pus forms in a lung cavity. An abscess is usually treated with antibiotics. Sometimes, surgery or drainage with a long needle or tube inserted into the abscess is needed to remove the pus.