Aspiration Pneumonia: Causes, Diagnosis, and Treatments

Pneumonia is a lung infection caused by bacteria, viruses, or fungi. Anyone can get pneumonia. But it’s most common in very young children and older adults. People with weak immune systems and chronic medical problems are also more at risk.  

Aspiration pneumonia is a bacterial lung infection with a specific cause — an aspiration event.

What is aspiration pneumonia?

During an aspiration event, stomach or mouth contents accidentally travel past the vocal cords and down into the trachea (windpipe). From there, it can easily enter the lungs, which people often describe as something “going down the wrong pipe.” These contents typically include things like:

• Saliva

• Food

• Drinking liquids

• Vomit 

Once in the lungs, the aspirated contents can irritate the lung tissues. Bacteria are usually present when you aspirate because they live in the mouth and nose. But the lungs are normally a sterile environment. So if bacteria reach the lungs, this can start an infection and lead to pneumonia.

What causes aspiration pneumonia?

Aspiration pneumonia is most commonly caused by uncoordinated swallowing. Or it can be due to decreased levels of alertness. Swallowing requires coordination of nerves and muscles from the mouth to the stomach. 

There are three stages of swallowing:  

1. Oral stage: The tongue and other oral muscles push food or liquid toward the back of the throat.

2. Pharyngeal stage: Muscles around the vocal cords and throat block the entrance to the trachea. This is to keep food and liquid out as it moves into the esophagus (“food pipe”).

3. Esophageal stage: Muscles of the esophagus push food down to the stomach.

Problems at any of these stages can cause abnormal swallowing (dysphagia). This increases the risk for aspiration pneumonia.

The body has protective reflexes against aspiration — like coughing. And structures around the vocal cords usually stop food and liquids from passing into the trachea. This all happens without you even thinking about it. But in situations where you aren't fully alert, these protective reflexes don’t work as well. And you’re more likely to aspirate.

Who gets aspiration pneumonia?

Anyone can get aspiration pneumonia, but there are several risk factors. 

People with swallowing issues   

Many conditions can affect the ability to swallow normally. This often includes diseases involving the nerves and muscles of the head and neck. Conditions that can cause weakness of the muscles of the mouth, throat, and esophagus are:

• Parkinson’s disease

• Cerebral palsy

• Stroke

• Dementia

People with decreased consciousness

A reduced level of alertness can interfere with your protective reflexes against aspiration. Possible causes of decreased alertness include:

• Coma

• Brain injury

• General anesthesia or deep sedation

• Alcohol or drug intoxication

• Seizures

People with coexisting medical conditions

Medical conditions that increase the risk of vomiting can make an aspiration more likely. Some examples include:

• Gastroesophageal reflux disease (GERD)

• Narrowing of the esophagus

• Bowel obstruction

• Obesity

• Pregnancy and labor

What are signs and symptoms of aspiration pneumonia?

In general, the most common symptoms of aspiration pneumonia are similar to any other type of pneumonia. They include:

• Fever

• Difficulty breathing

• Wheezing

• Cough

• Chest pain

• Low energy

• Confusion, especially in older adults

The severity of an aspiration event can widely vary. Some aspirations go unnoticed and include small amounts of material multiple times per day. Others may include choking, gagging, or a coughing event followed by immediate symptoms.

Immediate symptoms can include coughing that won’t go away or difficulty breathing. But these are usually a sign of lung irritation (pneumonitis) — not infection. In most cases, aspiration pneumonia doesn’t develop until 24 to 48 hours after an aspiration event. By then, the bacteria have had time to grow and cause pneumonia. 

How do you diagnose aspiration pneumonia?

Diagnosing aspiration pneumonia begins with identifying the pneumonia. And then your provider will often look for the cause. When looking for possible causes of pneumonia, providers will always consider aspiration. This is especially true in those who are older or have other risk factors. 

Your provider has different tools to diagnose pneumonia, including:

• Medical history: Your symptoms, medical conditions, and a history of similar problems are useful. They help give your provider context to the situation.

• Physical exam: Listening to your chest with a stethoscope may identify abnormal lung sounds. Your vital signs and oxygen levels can alert your provider of breathing issues.

• Lab studies: Special blood tests and bacterial cultures help look for signs of infection.

• Chest X-ray: A chest X-ray can show areas of the lungs filled with infection.  

• Chest CT: In some cases, a chest CT may be needed to look more closely at the lungs. 

• Bronchoscopy: Bronchoscopy is a medical procedure where your provider takes a sample of lung fluids. This helps to to look for evidence of aspirated material or infection.

What are the treatments for aspiration pneumonia?

Aspiration pneumonia is caused by bacteria. And one of the most important treatments is antibiotics. The type of antibiotic your provider chooses will depend on the bacteria most likely causing the infection. 

In addition to antibiotics, supportive care is often necessary until the pneumonia improves. This can include:

• Fever control

• Hydration

• Rest

• Oxygen

• Breathing treatments

• Intubation (breathing tube)

Even with treatment, aspiration pneumonia can be dangerous. In fact, the risk of death can be up to 30%. Recognizing the signs and starting treatment early may help improve recovery.

Preventing aspiration pneumonia is also key — especially for those most at risk. This may include feeding tubes to bypass the swallowing issues. Good oral care is also important to reduce the amount of oral bacteria.

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Written by:

Stephanie R. McGuire, MD, FASA

Stephanie R. McGuire, MD, is a freelance medical writer and pediatric anesthesiologist. She has more than a decade of experience in clinical pediatric anesthesiology, pediatric pain management, and medical education.

Edited by:

Karla Robinson, MD

Karla Robinson, MD, is a medical editor for GoodRx. She is a licensed, board-certified family physician with almost 20 years of experience in health through varied clinical, administrative, and educational roles.

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