What to Know About Lung Infections

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Different types of lung infections can impact various parts of the respiratory tract. For example, pneumonia affects the air sacs in the lungs, while bronchitis impacts the larger airways, or bronchi. Common symptoms associated with these infections include cough, chills, wheezing, and fever. A lung infection can be caused by viruses, bacteria, or fungi.

This article will go over what causes a lung infection, the signs and symptoms of a lung infection, as well as when you should see a provider for treatment.

Different Types of Lung Infections

Verywell / Shideh Ghandeharizadeh

What Is a Lung Infection?

A lung infection happens when a disease-causing microorganism like bacteria or a virus causes damage and inflammation in the lungs. This happens because immune cells race to the airways or tissues of the lungs to fight the infection.

Lung infections can be caused by viruses, bacteria, fungi, or parasites (though this is rare in the United States). In some cases, more than one type of germ causes lung infections. For example, viral bronchitis can lead to bacterial pneumonia.

Lung infections can be mild or severe. People of any age can get lung infections but some types are more common in people of certain ages. Lung infections can happen in different parts of the airways (e.g., bronchi, bronchioles, alveoli) or the tissues that surround the lungs.

Common Lung Infection Symptoms

A lung infection of any type that's from any cause tends to cause certain symptoms. Here are some of the most common symptoms of a lung infection:

  • Cough: A cough that is dry (nonproductive—does not bring up mucus) or “wet” (productive); can be mild or severe.
  • Mucus production: Mucus can be clear, yellow, green, brown, or rust-colored and may have no odor or a foul odor.
  • Wheezing: Wheezing when breathing out but sometimes when breathing in, too. A different sound—a higher pitched than wheezing called stridor—may happen when breathing in. Stridor is common with infections in the airways above the lungs, like the windpipe (trachea).
  • Fever: Temperature can be low-grade (less than 100 degrees F), high, or very high.
  • Chills or rigors (shaking chills): Chills can occur as a fever goes up, and sometimes sweats (which can be drenching) may come on as the fever goes down.
  • Upper respiratory symptoms: Nasal congestion, sore throat, hoarseness, laryngitis, and headaches commonly occur, especially with viral infections.

Other possible symptoms of a lung infection include:

Less Common Lung Infection Symptoms

There are also some less common, but still important to know, symptoms of a lung infection:

When to Call a Healthcare Provider for a Lung Infection

If you have a lung infection, you should let your provider know. At the very least, they will want to keep an eye on you.

Your provider might want to do tests to find out what is causing your lung infection. They can take a sample of the stuff you cough up (sputum) or a blood sample. Often, they can use these fluids to find out what is causing the infection—for example, bacteria and viruses.

Depending on the cause of the infection, how severe your symptoms are, and whether you have any other health conditions or concerns, they may want to do tests to see how your lungs are holding up, like having you breathe into a special device (spirometry) or having medical images of your chest taken (X-ray or CT scan).

When to Seek Medical Care for a Lung Infection

If you have a lung infection, certain signs and symptoms mean you need medical care:

  • High fever (over 100.5 to 101 degrees F)
  • Symptoms that do not start getting better after two weeks (though a cough can sometimes last longer)
  • Coughing up blood or rust-colored sputum
  • Shortness of breath (especially at rest)
  • Chest pain (other than a mild ache from coughing)
  • Rapid respiratory rate
  • Fast pulse (a heart rate greater than 100 beats per minute) or palpitations
  • Lightheadedness
  • Confusion or falls (in older adults)
  • Poor feeding or lethargy (infants)
  • Signs of dehydration such as thirst, and few wet diapers, and failure to cry tears in infants
  • Nausea and vomiting

Types of Lung Infections

Lung infections are grouped into different types depending on how they affect the lungs and airways.

Some organisms are more likely to cause a certain type of lung infection, but there can also be some overlap between them. For example, some viruses can cause bronchitis and pneumonia.

Bronchitis

Bronchitis is an infection of the large airways (bronchi) that travel between the windpipe (trachea) and the smaller airways.

Bronchitis is most commonly caused by a viral infection. In 1% to 10% of cases, a bacterial infection is the cause.

Bronchiolitis

Bronchiolitis is an infection of the smaller airways (bronchioles) between the larger bronchi and the tiny alveoli where the exchange of oxygen and carbon dioxide takes place.

Bronchiolitis is common in children under two years old and is the leading cause of hospitalizations of infants during the first year of life. That said, most children do not need to be hospitalized if they get sick with it.

After recovery, children who have had bronchiolitis may have an increased risk of developing recurrent wheezing or asthma during childhood and even into adulthood.

Common Cold

The common cold is responsible for 60% to 80% of school absences in children and 30% to 50% of time lost from work for adults.

During the first six years of life, children have, on average, six to eight colds per year. For most healthy adults, it drops down to three to four colds per year.

Coronaviruses and COVID-19

The COVID-19 pandemic made people more aware of coronaviruses, but the one that causes COVID (SARS-CoV-2) is just one of several coronaviruses that infect humans.

Other respiratory illnesses in humans that are caused by coronaviruses are severe acute respiratory syndrome (SARS) and Middle Eastern Respiratory Syndrome (MERS).

Enterovirus

Non-polio enteroviruses are a group of common viruses that can cause lung infections. They also cause hand, foot, and mouth disease (enterovirus A71), and severe infections in other parts of the body like myocarditis (inflammation of the heart), meningitis (inflammation of the protective layer around the brain), and encephalitis (brain infection or inflammation).

Lung infections caused by enterovirus often start with cold-like symptoms such as a fever, runny nose, body aches, and sometimes a rash.

Croup

Croup affects the structures above the lungs (larynx and trachea) but can also involve the bronchi.

Coup is usually caused by viruses, including common cold viruses and respiratory syncytial virus (RSV) but can also be caused by a bacterial infection.

The symptoms of croup often begin with a low-grade fever and runny nose, followed by the characteristic barking cough that gets worse at night.

Influenza

Seasonal influenza—or "the flu"—is one of the most common lung infections. Both influenza A and influenza B viruses are spread through droplets that come out of the body when a person coughs, sneezes, or even talks. That's why the flu is very contagious.

Symptoms of the flu include:

  • Fever and chills
  • Sore throat
  • Nasal congestion or a runny nose
  • Body aches
  • Headaches
  • Fatigue
  • A mild cough

Whooping Cough (Pertussis)

Whooping cough (pertussis) is often thought of as a vaccine-preventable lung infection of the past, but people still get it today.

Whooping cough can cause mild to severe illness, but it's mostly of concern for infants and young children—around 50% of babies under 12 months of age who get whooping cough need to be in the hospital.

About a fourth of babies and young children who get whooping cough will develop pneumonia. Less commonly (0.3%), complications of whooping cough such as encephalitis may occur.

Could a Lung Infection Be Whooping Cough?

You should know the signs and symptoms of whooping cough, even if you and your family have been vaccinated against it. While it can be a serious lung infection, early diagnosis and treatment can help make the cough less severe.

Tuberculosis

Tuberculosis (TB) is a lung infection that is more common in developing regions of the world. It is caused by a bacteria called Mycobacteria tuberculosis.

There are around 8,900 active TB infections in the United States each year, but the number of cases is the lowest it's been since we started keeping track in 1953.

Pneumonia

Pneumonia is a lung infection that affects the smallest of airways (alveoli) where the exchange of oxygen and carbon dioxide takes place.

Pneumonia can be a mild illness that's easily treated at home, but can also be a life-threatening infection that requires intensive care

The symptoms of pneumonia include:

  • A feeling of being very unwell (which can come on fast)
  • A cough (though the cough with pneumonia can be similar to one from bronchitis)
  • Phlegm production that is rust-colored or contains blood
  • High fever and chills
  • Shortness of breath
  • Chest pain
  • Fast respiratory rate
  • Fast pulse

Risk Factors for Lung Infections

Risk factors for lung infections vary based on the type, but there are certain things that can increase your risk of lung problems in general.

Common Risk Factors

Some of the most common risk factors for lung infections include:

  • Smoking or exposure to secondhand smoke
  • Exposure to air pollution or dust at work
  • A history of asthma or allergies
  • Crowded living conditions
  • Winter months in the northern hemisphere
  • Dry mucous membranes
  • Gastroesophageal reflux disease (GERD)
  • Anatomical differences in the face, head, neck, or airways (e.g., nasal polyps or a deviated septum)
  • Lower socioeconomic status
  • Malnutrition
  • Not being vaccinated (e.g., pneumococcal vaccines in children or the pneumonia shot in eligible adults)

Risk Factors in Children

Risk factors for lung infections in kids include:

  • Greater exposure to infections at daycare or school, or having multiple siblings
  • Being male
  • Prematurity
  • Bottle feeding instead of breastfeeding
  • Pacifier use
  • Age (children under the age of 6 are more susceptible in general, and bronchiolitis occurs most often in children under the age of 2)
  • Children born to people who smoked during pregnancy
  • Congenital heart and/or lung diseases

Less Common Risk Factors

While these risk factors for lung infections are less common, they're still important to keep in mind:

Lung Infection Treatment

The treatment for a lung infection depends on what is causing it and how sick a person is, as well as whether they have any other health conditions.

Home Remedies

Home remedies for lung infections include:

Prescription Medications and Hospital Treatment

Bacterial lung infections can be treated with antibiotics, but viral lung infections need to "run their course." However, people with lung infections from any cause may need medical treatment if they have severe symptoms.

For example, people who develop narrowing of the airways with a lung infection (reactive airway disease) may need inhalers that open the airways and corticosteroids to help with inflammation.

People who develop low oxygen levels (hypoxia) from a lung infection might need oxygen therapy, and severe cases may need assisted breathing or mechanical ventilation to help with breathing.

Viral Lung Infections

With viral lung infections, treatment is about helping a person feel as comfortable as possible while they are healing. Lung infections caused by a virus cannot be treated with antibiotics.

Here are a few examples of how different viral lung infections might be treated:

  • For someone with influenza A, treatment with Tamiflu (oseltamivir) may reduce the severity and duration of the infection if it's started early.
  • For very high-risk children with bronchiolitis from RSV, a monoclonal antibody treatment might be given.
  • There are different COVID-19 treatments being tried but we're still learning about which ones help and which ones do not. If your provider thinks you are at risk for complications, they might want you to take antiviral medications.

Bacterial Lung Infections

Antibiotics are the mainstay of treatment for bacterial lung infections. The antibiotic that will be used will depend on which bacteria is causing the infection.

In some cases, a provider may choose to start antibiotics while they are waiting for tests to come back. Once they know which bacteria is the cause of the infection, they might change the antibiotic.

Depending on how sick a person is, they might be able to take the medication by mouth (oral antibiotics) or they might need to have it through an IV.

The timing is also important. For example, with pneumonia, antibiotics need to be started as soon as possible.

Fungal and Parasitic Lung Infections

Anti-fungal medications such as Diflucan (fluconazole), Nizoral (ketoconazole), or Ancobon (flucytosine) are used to treat fungal lung infections.

Parasitic lung infections are treated with anti-parasitic medications. The medication chosen will depend on the parasite that's causing the infection.

Lung Infection Complications

A lung infection can be a serious illness by itself, but it can also lead to more health problems—some of which can be serious. The complications of a lung infection can happen soon after a person gets sick (acute) or later (chronic).

Acute

Some of the acute complications of lung infections are breathing problems. For example, viral lung infections can trigger an asthma attack in patients who have asthma.

Lung infections can also cause exacerbations in people with chronic obstructive pulmonary disease (COPD), which can in turn worsen that condition.

Chronic

Some effects of a lung infection don't go away when a person gets better. For example, babies and kids who get bronchiolitis are at an increased risk of having wheezing and asthma later in childhood.

There is also concern that viral lung infections could play a role in a person's risk of getting COPD.

Summary

Lung infections are often caused by viruses and bacteria, like influenza, COVID, and pneumonia. It's also possible to get a lung infection caused by fungi and parasites, but it's less common.

Lung infections can affect different parts of the respiratory tract. They can cause mild to severe symptoms and illness. Some people, like babies, children, older adults, and people with chronic medical conditions, are at a higher risk of getting very sick and having complications from lung infections.

Some complications of lung infections, like breathing problems, can start as soon as a person gets sick and might require medical care. Others, like asthma and COPD, might not come on until later or might last even after a person recovers from a lung infection.

The treatment for lung infections depends on what is causing it and how sick a person is. If you have symptoms of a lung infection, tell your provider. You might be able to treat a lung infection at home with rest, fluids, OTC products, and home remedies. If you need medical treatment like antibiotics, your provider can prescribe them for you.

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By Lynne Eldridge, MD
 Lynne Eldrige, MD, is a lung cancer physician, patient advocate, and award-winning author of "Avoiding Cancer One Day at a Time."