Last Updated: December 13, 2022

Pneumonia is an infection that inflames the air sacs and lower airways of the lungs, causing them to fill with fluid. Signs and symptoms of pneumonia include fever and chills, difficulty breathing, fatigue, and cough (with or without mucus). Cases caused by bacteria are treated with antibiotics.

Pneumonia falls under theImmunity & Infectious DiseaseandLungs & Breathingcategories.

What is pneumonia?

Pneumonia is an infection of the alveoli (air sacs) and lower airways in the lungs that causes inflammation and fluid accumulation. There are two main types: community acquired pneumonia (CAP) and nosocomial pneumonia (acquired in the hospital). Many pathogens, including bacteria, fungi, and viruses, can cause pneumonia,[1] but, in some cases, the cause cannot be identified.[2]

What are the main signs and symptoms of pneumonia?

Common signs and symptoms of pneumonia are shortness of breath, cough with or without mucus, chest pain, low blood oxygen levels, fever, chills, and fatigue. There may also be audible signs of fluid in the lungs, which a clinician can hear with a stethoscope. The severity of these signs and symptoms varies, ranging from mild respiratory distress to septic shock (characterized by a dangerous drop in blood pressure).

Certain populations have a different presentation of pneumonia. Younger children (<5 years) may be restless, vomit, have trouble eating, and show signs of breathing difficulties (e.g., nasal flaring, grunting, and chest retractions).[3][4] In older adults (>65 years), signs and symptoms may be less noticeable and could include disorientation or delirium.[1][5]

How is pneumonia diagnosed?

A pneumonia diagnosis is usually based on signs and symptoms in combination with chest imaging (e.g., X-ray or computed tomography) that shows signs of a lung infection. Since pneumonia presents similarly to other medical conditions, it is important to see a clinician for a diagnosis. A clinician will acquire a medical history and conduct a physical assessment to guide the choice of any necessary treatments, imaging, and/or blood tests. These tests will help rule out other possible causes of symptoms, like the flu, asthma, or pulmonary embolism.

What are some of the main medical treatments for pneumonia?

Antibiotics are the first-line treatment for most cases of pneumonia. The choice of antibiotic, however, will depend upon the clinician weighing the risks and benefits of antibiotic therapy, the person’s medical history, and local epidemiological data (community outbreaks, microbe prevalence, etc.).[1] If testing (e.g., blood and sputum cultures, nasal swabs) indicates the causative pathogen is not a bacteria, an antiviral (to fight viruses) or an antifungal (to fight fungi) may be given.

Corticosteroids are not indicated for use in people with uncomplicated pneumonia; instead, they are reserved for people whose pneumonia is exacerbating preexisting reactive airway disease (e.g., COPD), or who are critically ill (e.g., septic shock) and not responding to usual treatments. Moderate to severe cases of pneumonia may also require supportive treatments, such as oxygen therapy, IV fluids, blood pressure medications, and airway/breathing support. [6] Aerosolized antibiotics are sometimes used in hospital settings for ventilator-associated pneumonia, but there is no robust evidence to support their efficacy. [7]

Have any supplements been studied for pneumonia?

Many supplements have been studied for pneumonia, but there is little evidence to support their efficacy. For instance, a meta-analysis found that Vitamin C was ineffective in treating or preventing pneumonia.[8] Similarly, probiotics, specifically the strain Lactobacillus rhamnosus GG, failed to prevent ventilator-associated pneumonia.[9]

Although there is some evidence that low levels of vitamin D (measured by plasma 25-hydroxyvitamin D3) are associated with an increased risk of bacterial pneumonia[10], it’s unclear whether supplementation reduces this risk. Lastly, a randomized controlled trial found that N-Acetylcystine (NAC) supplementation, despite lowering markers of oxidative stress and inflammation, did not improve chest imaging results in people hospitalized with pneumonia.[11]

Conversely, zinc supplementation is associated with a reduced risk of pneumonia in children,[12] but adding zinc as an adjunct to antibiotic treatment in children who already have pneumonia does not improve time to recovery.[13][14]

How could diet affect pneumonia?

There is minimal evidence that diet affects pneumonia. A cohort study found that increased coffee, tea, oily fish, and fruit were associated with a reduced risk of developing pneumonia, while increased red meat intake was associated with an increased risk of developing pneumonia.[15] Given that this is observational data, controlled studies are needed to better determine the relationship between dietary patterns and pneumonia. Regardless of dietary pattern, people with pneumonia must meet their daily nutritional needs, as severe malnutrition in both young children (<5 years) and older adults (>65 years) with pneumonia is associated with an increased risk of mortality.[16][16] Some studies have also found that increasing energy and protein intake can improve health outcomes in people who are hospitalized for severe pneumonia.[17][18]

Are there any other treatments for pneumonia?

Some research suggests that increased physical activity[19] and sauna bathing[20][21] are associated with a decreased risk of developing pneumonia. Another common treatment is chest physiotherapy, which involves manual techniques to help clear mucus out of the airways. However, most studies don’t find it very useful.[22][23]

What causes pneumonia?

Many types of pathogens can cause pneumonia, such as:

  • Bacteria: Streptococcus pneumoniae, Haemophilus influenzae, Mycoplasma pneumoniae, Legionella pneumophila, and methicillin-resistant Staphylococcus aureus (MRSA)

  • Viruses: Human rhinovirus, influenza A or B, coronavirus, and respiratory syncytial virus (RSV)

  • Fungi: Pneumocystis jirovecii, Aspergillus spp., and Mucorales

The most prevalent causative microbes vary geographically. Viruses account for the majority of cases in children (<5 years)[24], whereas bacteria and viruses account for most cases of pneumonia in adults. Fungal pneumonia is quite rare and usually occurs in people who are immunocompromised (e.g., cancer patients).[1]

Pneumonia can also be caused by foods, liquids, or gastric contents inadvertently entering the lungs, a condition known as aspiration pneumonia.

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  1. ^Torres A, Cilloniz C, Niederman MS, Menéndez R, Chalmers JD, Wunderink RG, van der Poll TPneumonia.Nat Rev Dis Primers.(2021-Apr-08)
  2. ^Musher DM, Abers MS, Bartlett JGEvolving Understanding of the Causes of Pneumonia in Adults, With Special Attention to the Role of Pneumococcus.Clin Infect Dis.(2017-Oct-30)
  3. ^Shah SN, Bachur RG, Simel DL, Neuman MIDoes This Child Have Pneumonia?: The Rational Clinical Examination Systematic Review.JAMA.(2017-Aug-01)
  4. ^Bradley JS, Byington CL, Shah SS, Alverson B, Carter ER, Harrison C, Kaplan SL, Mace SE, McCracken GH, Moore MR, St Peter SD, Stockwell JA, Swanson JT,The management of community-acquired pneumonia in infants and children older than 3 months of age: clinical practice guidelines by the Pediatric Infectious Diseases Society and the Infectious Diseases Society of America.Clin Infect Dis.(2011-Oct)
  5. ^Cilloniz C, Ceccato A, San Jose A, Torres AClinical management of community acquired pneumonia in the elderly patient.Expert Rev Respir Med.(2016-Nov)
  6. ^Metlay JP, Waterer GW, Long AC, Anzueto A, Brozek J, Crothers K, Cooley LA, Dean NC, Fine MJ, Flanders SA, Griffin MR, Metersky ML, Musher DM, Restrepo MI, Whitney CGDiagnosis and Treatment of Adults with Community-acquired Pneumonia. An Official Clinical Practice Guideline of the American Thoracic Society and Infectious Diseases Society of America.Am J Respir Crit Care Med.(2019-Oct-01)
  7. ^Xu F, He LL, Che LQ, Li W, Ying SM, Chen ZH, Shen HHAerosolized antibiotics for ventilator-associated pneumonia: a pairwise and Bayesian network meta-analysis.Crit Care.(2018-Nov-15)
  8. ^Padhani ZA, Moazzam Z, Ashraf A, Bilal H, Salam RA, Das JK, Bhutta ZAVitamin C supplementation for prevention and treatment of pneumonia.Cochrane Database Syst Rev.(2021-Nov-18)
  9. ^Johnstone J, Meade M, Lauzier F, Marshall J, Duan E, Dionne J, Arabi YM, Heels-Ansdell D, Thabane L, Lamarche D, Surette M, Zytaruk N, Mehta S, Dodek P, McIntyre L, English S, Rochwerg B, Karachi T, Henderson W, Wood G, Ovakim D, Herridge M, Granton J, Wilcox ME, Goffi A, Stelfox HT, Niven D, Muscedere J, Lamontagne F, D'Aragon F, St-Arnaud C, Ball I, Nagpal D, Girard M, Aslanian P, Charbonney E, Williamson D, Sligl W, Friedrich J, Adhikari NK, Marquis F, Archambault P, Khwaja K, Kristof A, Kutsogiannis J, Zarychanski R, Paunovic B, Reeve B, Lellouche F, Hosek P, Tsang J, Binnie A, Trop S, Loubani O, Hall R, Cirone R, Reynolds S, Lysecki P, Golan E, Cartin-Ceba R, Taylor R, Cook D,Effect of Probiotics on Incident Ventilator-Associated Pneumonia in Critically Ill Patients: A Randomized Clinical Trial.JAMA.(2021-Sep-21)
  10. ^Çolak Y, Nordestgaard BG, Afzal SLow vitamin D and risk of bacterial pneumonias: Mendelian randomisation studies in two population-based cohorts.Thorax.(2021-May)
  11. ^Zhang Q, Ju Y, Ma Y, Wang TN-acetylcysteine improves oxidative stress and inflammatory response in patients with community acquired pneumonia: A randomized controlled trial.Medicine (Baltimore).(2018-Nov)
  12. ^Lassi ZS, Moin A, Bhutta ZAZinc supplementation for the prevention of pneumonia in children aged 2 months to 59 months.Cochrane Database Syst Rev.(2016-Dec-04)
  13. ^Haider BA, Lassi ZS, Ahmed A, Bhutta ZAZinc supplementation as an adjunct to antibiotics in the treatment of pneumonia in children 2 to 59 months of age.Cochrane Database Syst Rev.(2011-Oct-05)
  14. ^Brown N, Kukka AJ, Mårtensson AEfficacy of zinc as adjunctive pneumonia treatment in children aged 2 to 60 months in low-income and middle-income countries: a systematic review and meta-analysis.BMJ Paediatr Open.(2020)
  15. ^Vu TT, Van Horn L, Achenbach CJ, Rydland KJ, Cornelis MCDiet and Respiratory Infections: Specific or Generalized Associations?Nutrients.(2022-Mar-11)
  16. ^Yeo HJ, Byun KS, Han J, Kim JH, Lee SE, Yoon SH, Jeon D, Kim YS, Cho WHPrognostic significance of malnutrition for long-term mortality in community-acquired pneumonia: a propensity score matched analysis.Korean J Intern Med.(2019-Jul)
  17. ^Tang W, Shao X, Chen Q, Zhu L, He Y, Lu ENutritional status of protein intake in severe pneumonia patients based on dietary nutrition information system.J Infect Public Health.(2021-Jan)
  18. ^Yang PH, Lin MC, Liu YY, Lee CL, Chang NJEffect of Nutritional Intervention Programs on Nutritional Status and Readmission Rate in Malnourished Older Adults with Pneumonia: A Randomized Control Trial.Int J Environ Res Public Health.(2019-Nov-27)
  19. ^Setor K Kunutsor, Samuel Seidu, Jari A LaukkanenPhysical activity reduces the risk of pneumonia: systematic review and meta-analysis of 10 prospective studies involving 1,044,492 participantsGeroscience.(2021 Nov 25)
  20. ^Setor K Kunutsor, Sae Young Jae, Jari A LaukkanenAttenuated Risk of Pneumonia Due to Inflammation by Frequent Sauna Baths: A PROSPECTIVE COHORT STUDYJ Cardiopulm Rehabil Prev.(2021 Mar 26)
  21. ^Kunutsor SK, Laukkanen T, Laukkanen JAFrequent sauna bathing may reduce the risk of pneumonia in middle-aged Caucasian men: The KIHD prospective cohort study.Respir Med.(2017-Nov)
  22. ^Chen X, Jiang J, Wang R, Fu H, Lu J, Yang MChest physiotherapy for pneumonia in adults.Cochrane Database Syst Rev.(2022-Sep-06)
  23. ^Chaves GS, Freitas DA, Santino TA, Nogueira PAM, Fregonezi GA, Mendonça KMChest physiotherapy for pneumonia in children.Cochrane Database Syst Rev.(2019-Jan-02)
  24. ^Jain S, Williams DJ, Arnold SR, Ampofo K, Bramley AM, Reed C, Stockmann C, Anderson EJ, Grijalva CG, Self WH, Zhu Y, Patel A, Hymas W, Chappell JD, Kaufman RA, Kan JH, Dansie D, Lenny N, Hillyard DR, Haynes LM, Levine M, Lindstrom S, Winchell JM, Katz JM, Erdman D, Schneider E, Hicks LA, Wunderink RG, Edwards KM, Pavia AT, McCullers JA, Finelli L,Community-acquired pneumonia requiring hospitalization among U.S. children.N Engl J Med.(2015-Feb-26)
Examine Database References
  1. Pneumonia Symptoms - Chandyo RK, Shrestha PS, Valentiner-Branth P, Mathisen M, Basnet S, Ulak M, Adhikari RK, Sommerfelt H, Strand TATwo weeks of zinc administration to Nepalese children with pneumonia does not reduce the incidence of pneumonia or diarrhea during the next six monthsJ Nutr.(2010 Sep)
  2. Pneumonia Symptoms - Shah GS, Dutta AK, Shah D, Mishra OPRole of zinc in severe pneumonia: a randomized double bind placebo controlled studyItal J Pediatr.(2012 Aug 2)
  3. Pneumonia Symptoms - Wadhwa N, Chandran A, Aneja S, Lodha R, Kabra SK, Chaturvedi MK, Sodhi J, Fitzwater SP, Chandra J, Rath B, Kainth US, Saini S, Black RE, Santosham M, Bhatnagar SEfficacy of zinc given as an adjunct in the treatment of severe and very severe pneumonia in hospitalized children 2-24 mo of age: a randomized, double-blind, placebo-controlled trialAm J Clin Nutr.(2013 Jun)
  4. Pneumonia Symptoms - Srinivasan MG, Ndeezi G, Mboijana CK, Kiguli S, Bimenya GS, Nankabirwa V, Tumwine JKZinc adjunct therapy reduces case fatality in severe childhood pneumonia: a randomized double blind placebo-controlled trialBMC Med.(2012 Feb 8)
  5. Pneumonia Symptoms - Ganguly A, Chakraborty S, Datta K, Hazra A, Datta S, Chakraborty JA randomized controlled trial of oral zinc in acute pneumonia in children aged between 2 months to 5 yearsIndian J Pediatr.(2011 Sep)
  6. Pneumonia Symptoms - Valentiner-Branth P, Shrestha PS, Chandyo RK, Mathisen M, Basnet S, Bhandari N, Adhikari RK, Sommerfelt H, Strand TAA randomized controlled trial of the effect of zinc as adjuvant therapy in children 2-35 mo of age with severe or nonsevere pneumonia in Bhaktapur, NepalAm J Clin Nutr.(2010 Jun)
  7. Pneumonia Symptoms - Basnet S, Shrestha PS, Sharma A, Mathisen M, Prasai R, Bhandari N, Adhikari RK, Sommerfelt H, Valentiner-Branth P, Strand TA; Zinc Severe Pneumonia Study GroupA randomized controlled trial of zinc as adjuvant therapy for severe pneumonia in young childrenPediatrics.(2012 Apr)
  8. Pneumonia Symptoms - Valavi E, Hakimzadeh M, Shamsizadeh A, Aminzadeh M, Alghasi AThe efficacy of zinc supplementation on outcome of children with severe pneumonia. A randomized double-blind placebo-controlled clinical trialIndian J Pediatr.(2011 Sep)
  9. Pneumonia Symptoms - Manaseki-Holland S, Qader G, Isaq Masher M, Bruce J, Zulf Mughal M, Chandramohan D, Walraven GEffects of vitamin D supplementation to children diagnosed with pneumonia in Kabul: a randomised controlled trialTrop Med Int Health.(2010 Oct)
  10. Pneumonia Symptoms - Choudhary N, Gupta PVitamin D supplementation for severe pneumonia--a randomized controlled trialIndian Pediatr.(2012 Jun)
  11. Gastric Emptying Rate - Shariatpanahi ZV, Taleban FA, Mokhtari M, Shahbazi SGinger extract reduces delayed gastric emptying and nosocomial pneumonia in adult respiratory distress syndrome patients hospitalized in an intensive care unitJ Crit Care.(2010 Dec)