Aspiration Pneumonia - Symptoms and Causes

Who gets aspiration pneumonia?

  • Healthy adults can fight a few germs that enter the lungs from other areas of the body. It's not surprising therefore that aspiration occurs mainly in the elderly and frail. Men are affected more than women.
  • It's fairly common. Research suggests that of all the cases of pneumonia that occur outside hospital (community-acquired pneumonia) about 1 in 10 is caused by aspiration pneumonia.
  • It's also common in children.
  • It occurs frequently in hospitals, where lots of germs may be involved in causing it.

What are the symptoms of aspiration pneumonia?

  • You may feel generally unwell, with a high temperature (fever), headache, sickness (vomiting) and muscle aches. You might go off your food and lose a little bit of weight.
  • A cough is the key feature, sometimes with yellow or green phlegm.
  • Your breathing rate and pulse may become rapid.
  • Other symptoms you may notice include breathlessness and chest pain which is worse when you breathe in deeply.
  • A doctor listening to your chest with a stethoscope might hear that your breathing sounds muffled and that the covering of your lungs makes a sound when you breathe in and out (a pleural rub).
  • If your chest wall is tapped, the doctor may find an area of dullness.
  • Untreated, pneumonia can make you feel very ill. The oxygen you breathe in may have difficulty getting to parts of your body distant from your lungs (for example, your lips and tongue) and may develop a blue tinge.

What causes aspiration pneumonia?

Aspiration pneumonia is caused by saliva, food or stomach acid leaking into the lungs. Germs (bacteria) introduced by this route set up an infection of the lung tissue, resulting in pneumonia. This is unlikely to happen if you're a young, fit adult. However, certain factors increase the risk of getting aspiration pneumonia. These include:

  • Being drowsy or unconscious - when you are awake you are continually clearing your throat to protect the lungs from inhaled saliva, drinks or bits of food. If your consciousness is reduced, the throat muscles tend to relax, increasing the risk of aspiration. This can happen if you:
    • Are under the influence of alcohol or drugs.
    • Have an anaesthetic.
    • Have a fit.
    • Have a stroke.
    • Have a disease of the nervous system.
    • Have problems swallowing - for example, due to a stroke, a tumour of the lower part of the throat (pharynx), or a disease affecting the nerves and muscles involved in swallowing (for example, multiple sclerosis).
  • Having a condition that increases the amount of fluid near the lungs - for example:
    • Tracheo-oesophageal fistula - a channel between the airway and the food tube.
    • Artificial ventilation.
    • Gum disease.
    • Acid reflux.
    • Nasogastric feeding - feeding via a tube through the nose into the stomach. With modern nursing, this is less of a risk than it used to be,

A variety of bacteria may be involved - for example:

  • Those that are always around the mouth and throat, such as Streptococcus pneumoniae, Staphylococcus aureus and Haemophilus influenzae.
  • Those acquired in hospitals, such as Klebsiella pneumoniae, Escherichia coli, Pseudomonas aeruginosa and meticillin-resistant S. aureus (MRSA).

Did you find this information useful?

Thanks for your feedback!

Why not subcribe to the newsletter?

We would love to hear your feedback!



  • Armstrong JR, Mosher BD; Aspiration pneumonia after stroke: intervention and prevention. Neurohospitalist. 2011 Apr 1(2):85-93. doi: 10.1177/1941875210395775.
  • Ebihara S, Sekiya H, Miyagi M, et al; Dysphagia, dystussia, and aspiration pneumonia in elderly people. J Thorac Dis. 2016 Mar 8(3):632-9. doi: 10.21037/jtd.2016.02.60.
  • Kovesi T; Aspiration Risk and Respiratory Complications in Patients with Esophageal Atresia. Front Pediatr. 2017 Apr 3 5:62. doi: 10.3389/fped.2017.00062. eCollection 2017.
Author:
Dr Laurence Knott
Peer Reviewer:
Prof Cathy Jackson
Document ID:
29437 (v1)
Last Checked:
07 July 2017
Next Review:
06 July 2020

Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. Patient Platform Limited has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.