Viral gastroenteritis in adults
- Overview
- Theory
- Diagnosis
- Management
- Follow up
- Resources
Treatment algorithm
Please note that formulations/routes and doses may differ between drug names and brands, drug formularies, or locations. Treatment recommendations are specific to patient groups: see disclaimer
Look out for this icon: for treatment options that are affected, or added, as a result of your patient's comorbidities.
mild to moderate volume depletion
oral rehydration therapy (ORT)
ORT has two phases: 1) a rehydration phase, to replace existing losses, and 2) a maintenance phase, which includes both replacement of ongoing fluid and electrolyte losses and adequate dietary intake.
There is no standard formula for adults, but about 1 L/hour is required in most cases with ongoing losses.
Patients should be encouraged to drink plenty of fluids and take salt in soups and salted crackers.
Oral rehydration solution is recommended for people with acute diarrhea from any cause. It is also recommended for people with mild to moderate dehydration associated with vomiting or severe diarrhea.[19]Shane AL, Mody RK, Crump JA, et al. 2017 Infectious Diseases Society of America clinical practice guidelines for the diagnosis and management of infectious diarrhea. Clin Infect Dis. 2017 Nov 29;65(12):e45-80. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5850553 http://www.ncbi.nlm.nih.gov/pubmed/29053792?tool=bestpractice.com
One Cochrane review found that polymer-based oral rehydration solution (ORS) was more effective for treating acute watery diarrhea compared with glucose-based ORS.[30]Gregorio GV, Gonzales ML, Dans LF, Martinez EG. Polymer-based oral rehydration solution for treating acute watery diarrhoea. Cochrane Database Syst Rev. 2016 Dec 13;(12):CD006519. http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD006519.pub3/abstract http://www.ncbi.nlm.nih.gov/pubmed/27959472?tool=bestpractice.com
Regardless of fluid used, appropriate diet should also be given. Foods high in simple sugars, juice, highly sugared liquids, and fluids very low in sodium should be avoided as the osmotic load might worsen diarrhea; carbonated soft drinks should also be avoided.[28]King CK, Glass R, Bresee JS, et al. Managing acute gastroenteritis among children: oral rehydration, maintenance, and nutritional therapy. MMWR Recomm Rep. 2003 Nov 21;52(RR-16):1-16. https://www.cdc.gov/mmwr/preview/mmwrhtml/rr5216a1.htm http://www.ncbi.nlm.nih.gov/pubmed/14627948?tool=bestpractice.com [29]Farthing M, Salam MA, Lindberg G, et al. Acute diarrhea in adults and children: a global perspective. J Clin Gastroenterol. 2013 Jan;47(1):12-20. http://www.ncbi.nlm.nih.gov/pubmed/23222211?tool=bestpractice.com
antidiarrheal agent
Treatment recommended for SOME patients in selected patient group
Antidiarrheal agents may be used for symptomatic relief of watery diarrhea in adults, although they are not usually required. They may be considered, for example, as a specific strategy for short-term symptom management if a patient has to travel.
Avoid antidiarrheal agents in patients with bloody diarrhea (which may indicate a bacterial cause) or where an inflammatory cause is suspected, as it may prolong the infection.[25]Riddle MS, DuPont HL, Connor BA. ACG clinical guideline: diagnosis, treatment, and prevention of acute diarrheal infections in adults. Am J Gastroenterol. 2016 May;111(5):602-22. http://www.ncbi.nlm.nih.gov/pubmed/27068718?tool=bestpractice.com [36]Meisenheimer ES MD, MBA, Epstein C DO, Thiel D MD, MPH. Acute diarrhea in adults. Am Fam Physician. 2022 Jul;106(1):72-80. https://www.aafp.org/pubs/afp/issues/2022/0700/acute-diarrhea.html http://www.ncbi.nlm.nih.gov/pubmed/35839362?tool=bestpractice.com
Primary options
loperamide: 4 mg orally initially, followed by 2 mg after each loose stool, maximum 16 mg/day
OR
bismuth subsalicylate: 524 mg orally every hour when required, maximum 4200 mg/day
Secondary options
diphenoxylate/atropine: 5 mg orally four times daily initially, followed by 2.5 to 5 mg twice to four times daily when required, maximum 20 mg/day
More diphenoxylate/atropineDose refers to diphenoxylate component.
These drug options and doses relate to a patient with no comorbidities.
Primary options
loperamide: 4 mg orally initially, followed by 2 mg after each loose stool, maximum 16 mg/day
OR
bismuth subsalicylate: 524 mg orally every hour when required, maximum 4200 mg/day
Secondary options
diphenoxylate/atropine: 5 mg orally four times daily initially, followed by 2.5 to 5 mg twice to four times daily when required, maximum 20 mg/day
More diphenoxylate/atropineDose refers to diphenoxylate component.
Drug choice, dose and interactions may be affected by the patient's comorbidities. Check your local drug formulary.
Show drug information for a patient with no comorbidities
Primary options
loperamide
OR
bismuth subsalicylate
Secondary options
diphenoxylate/atropine
intravenous hydration or nasogastric hydration
Approximate fluid loss should be replaced in <3 hours, followed by maintenance fluid replacement for ongoing losses.
Volume depletion assessment should be repeated periodically and rate of fluid therapy modified based on signs of volume depletion.
If intravenous hydration is not available or it is delayed (e.g., venous access problems) and the patient is not able to tolerate oral fluids, a central line can be placed.
Nasogastric administration of oral rehydration solution may also be considered as an alternative.[19]Shane AL, Mody RK, Crump JA, et al. 2017 Infectious Diseases Society of America clinical practice guidelines for the diagnosis and management of infectious diarrhea. Clin Infect Dis. 2017 Nov 29;65(12):e45-80. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5850553 http://www.ncbi.nlm.nih.gov/pubmed/29053792?tool=bestpractice.com
Patients should be rehydrated with isotonic crystalloids, such as normal saline (0.9% sodium chloride), Ringer’s lactate, or Plasma-Lyte®.[19]Shane AL, Mody RK, Crump JA, et al. 2017 Infectious Diseases Society of America clinical practice guidelines for the diagnosis and management of infectious diarrhea. Clin Infect Dis. 2017 Nov 29;65(12):e45-80. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5850553 http://www.ncbi.nlm.nih.gov/pubmed/29053792?tool=bestpractice.com Evidence from two large randomized controlled trials (RCTs) suggests there is no difference between normal saline and a balanced crystalloid for critically ill patients in mortality at 90 days, although results from two meta-analyses including these RCTs point to a possible small benefit of balanced solutions compared with normal saline.[32]Finfer S, Micallef S, Hammond N, et al. Balanced multielectrolyte solution versus saline in critically ill adults. N Engl J Med. 2022 Mar 3;386(9):815-26. https://www.nejm.org/doi/10.1056/NEJMoa2114464?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub%20%200pubmed http://www.ncbi.nlm.nih.gov/pubmed/35041780?tool=bestpractice.com [33]Zampieri FG, Machado FR, Biondi RS, et al. Effect of intravenous fluid treatment with a balanced solution vs 0.9% saline solution on mortality in critically ill patients: The BaSICS Randomized Clinical Trial. JAMA. 2021 Aug 10;326(9):1-12. https://pmc.ncbi.nlm.nih.gov/articles/PMC8356144 http://www.ncbi.nlm.nih.gov/pubmed/34375394?tool=bestpractice.com [34]Hammond NE, Zampieri FG, Di Tanna GL, et al. Balanced crystalloids versus saline in critically ill adults - a systematic review with meta-analysis. NEJM Evid. 2022 Feb;1(2):EVIDoa2100010. https://evidence.nejm.org/doi/10.1056/EVIDoa2100010?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub%20%200pubmed http://www.ncbi.nlm.nih.gov/pubmed/38319180?tool=bestpractice.com [35]Zampieri FG, Cavalcanti AB, Di Tanna GL, et al. Balanced crystalloids versus saline for critically ill patients (BEST-Living): a systematic review and individual patient data meta-analysis. Lancet Respir Med. 2024 Mar;12(3):237-46. http://www.ncbi.nlm.nih.gov/pubmed/38043564?tool=bestpractice.com
antiemetic
Treatment recommended for SOME patients in selected patient group
Antiemetics (e.g., ondansetron) are recommended only for patients with intractable vomiting.
Primary options
ondansetron: 8 mg intravenously/orally every 8 hours when required
These drug options and doses relate to a patient with no comorbidities.
Primary options
ondansetron: 8 mg intravenously/orally every 8 hours when required
Drug choice, dose and interactions may be affected by the patient's comorbidities. Check your local drug formulary.
Show drug information for a patient with no comorbidities
Primary options
ondansetron
antidiarrheal agent
Treatment recommended for SOME patients in selected patient group
Antidiarrheal agents may be used for symptomatic relief of watery diarrhea in adults, if the patient can take oral drugs, although they are not usually required.
Avoid antidiarrheal agents in patients with bloody diarrhea (which may indicate a bacterial cause) or where an inflammatory cause is suspected, as it may prolong the infection.[25]Riddle MS, DuPont HL, Connor BA. ACG clinical guideline: diagnosis, treatment, and prevention of acute diarrheal infections in adults. Am J Gastroenterol. 2016 May;111(5):602-22. http://www.ncbi.nlm.nih.gov/pubmed/27068718?tool=bestpractice.com [36]Meisenheimer ES MD, MBA, Epstein C DO, Thiel D MD, MPH. Acute diarrhea in adults. Am Fam Physician. 2022 Jul;106(1):72-80. https://www.aafp.org/pubs/afp/issues/2022/0700/acute-diarrhea.html http://www.ncbi.nlm.nih.gov/pubmed/35839362?tool=bestpractice.com
Primary options
loperamide: 4 mg orally initially, followed by 2 mg after each loose stool, maximum 16 mg/day
OR
bismuth subsalicylate: 524 mg orally every hour when required, maximum 4200 mg/day
Secondary options
diphenoxylate/atropine: 5 mg orally four times daily initially, followed by 2.5 to 5 mg twice to four times daily when required, maximum 20 mg/day
More diphenoxylate/atropineDose refers to diphenoxylate component.
These drug options and doses relate to a patient with no comorbidities.
Primary options
loperamide: 4 mg orally initially, followed by 2 mg after each loose stool, maximum 16 mg/day
OR
bismuth subsalicylate: 524 mg orally every hour when required, maximum 4200 mg/day
Secondary options
diphenoxylate/atropine: 5 mg orally four times daily initially, followed by 2.5 to 5 mg twice to four times daily when required, maximum 20 mg/day
More diphenoxylate/atropineDose refers to diphenoxylate component.
Drug choice, dose and interactions may be affected by the patient's comorbidities. Check your local drug formulary.
Show drug information for a patient with no comorbidities
Primary options
loperamide
OR
bismuth subsalicylate
Secondary options
diphenoxylate/atropine
severe volume depletion
intravenous hydration
Patients with severe volume depletion, particularly those with altered mental state, should be rehydrated with isotonic crystalloids, such as normal saline (0.9% sodium chloride), Ringer’s lactate, or Plasma-Lyte®.[19]Shane AL, Mody RK, Crump JA, et al. 2017 Infectious Diseases Society of America clinical practice guidelines for the diagnosis and management of infectious diarrhea. Clin Infect Dis. 2017 Nov 29;65(12):e45-80. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5850553 http://www.ncbi.nlm.nih.gov/pubmed/29053792?tool=bestpractice.com
Evidence from two large randomized controlled trials (RCTs) suggests there is no difference between normal saline and a balanced crystalloid for critically ill patients in mortality at 90 days, although results from two meta-analyses including these RCTs point to a possible small benefit of balanced solutions compared with normal saline.[32]Finfer S, Micallef S, Hammond N, et al. Balanced multielectrolyte solution versus saline in critically ill adults. N Engl J Med. 2022 Mar 3;386(9):815-26. https://www.nejm.org/doi/10.1056/NEJMoa2114464?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub%20%200pubmed http://www.ncbi.nlm.nih.gov/pubmed/35041780?tool=bestpractice.com [33]Zampieri FG, Machado FR, Biondi RS, et al. Effect of intravenous fluid treatment with a balanced solution vs 0.9% saline solution on mortality in critically ill patients: The BaSICS Randomized Clinical Trial. JAMA. 2021 Aug 10;326(9):1-12. https://pmc.ncbi.nlm.nih.gov/articles/PMC8356144 http://www.ncbi.nlm.nih.gov/pubmed/34375394?tool=bestpractice.com [34]Hammond NE, Zampieri FG, Di Tanna GL, et al. Balanced crystalloids versus saline in critically ill adults - a systematic review with meta-analysis. NEJM Evid. 2022 Feb;1(2):EVIDoa2100010. https://evidence.nejm.org/doi/10.1056/EVIDoa2100010?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub%20%200pubmed http://www.ncbi.nlm.nih.gov/pubmed/38319180?tool=bestpractice.com [35]Zampieri FG, Cavalcanti AB, Di Tanna GL, et al. Balanced crystalloids versus saline for critically ill patients (BEST-Living): a systematic review and individual patient data meta-analysis. Lancet Respir Med. 2024 Mar;12(3):237-46. http://www.ncbi.nlm.nih.gov/pubmed/38043564?tool=bestpractice.com
Approximate fluid loss should be replaced in <3 hours, followed by maintenance fluid replacement for ongoing losses. Take care not to replete patients with hypernatremia or hyponatremia too quickly, as this can lead to complications, such as osmotic demyelination syndrome.[31]Miller NE, Rushlow D, Stacey SK. Diagnosis and management of sodium disorders: hyponatremia and hypernatremia. Am Fam Physician. 2023 Nov;108(5):476-86. http://www.ncbi.nlm.nih.gov/pubmed/37983699?tool=bestpractice.com Volume depletion assessment should be repeated periodically and rate of fluid therapy modified based on signs of volume depletion.
If intravenous hydration is not available or it is delayed (e.g., venous access problems) and the patient is not able to tolerate oral fluids, a central line can be placed.
antiemetic
Treatment recommended for SOME patients in selected patient group
Antiemetics (e.g., ondansetron) are recommended only for patients with intractable vomiting.
Primary options
ondansetron: 8 mg intravenously/orally every 8 hours when required
These drug options and doses relate to a patient with no comorbidities.
Primary options
ondansetron: 8 mg intravenously/orally every 8 hours when required
Drug choice, dose and interactions may be affected by the patient's comorbidities. Check your local drug formulary.
Show drug information for a patient with no comorbidities
Primary options
ondansetron
antidiarrheal agent
Treatment recommended for SOME patients in selected patient group
Antidiarrheal agents may be used for symptomatic relief of watery diarrhea in adults, if the patient can take oral drugs, although they are not usually required.
Avoid antidiarrheal agents in patients with bloody diarrhea (which may indicate a bacterial cause) or where an inflammatory cause is suspected, as it may prolong the infection.[25]Riddle MS, DuPont HL, Connor BA. ACG clinical guideline: diagnosis, treatment, and prevention of acute diarrheal infections in adults. Am J Gastroenterol. 2016 May;111(5):602-22. http://www.ncbi.nlm.nih.gov/pubmed/27068718?tool=bestpractice.com [36]Meisenheimer ES MD, MBA, Epstein C DO, Thiel D MD, MPH. Acute diarrhea in adults. Am Fam Physician. 2022 Jul;106(1):72-80. https://www.aafp.org/pubs/afp/issues/2022/0700/acute-diarrhea.html http://www.ncbi.nlm.nih.gov/pubmed/35839362?tool=bestpractice.com
Primary options
loperamide: 4 mg orally initially, followed by 2 mg after each loose stool, maximum 16 mg/day
OR
bismuth subsalicylate: 524 mg orally every hour when required, maximum 4200 mg/day
Secondary options
diphenoxylate/atropine: 5 mg orally four times daily initially, followed by 2.5 to 5 mg twice to four times daily when required, maximum 20 mg/day
More diphenoxylate/atropineDose refers to diphenoxylate component.
These drug options and doses relate to a patient with no comorbidities.
Primary options
loperamide: 4 mg orally initially, followed by 2 mg after each loose stool, maximum 16 mg/day
OR
bismuth subsalicylate: 524 mg orally every hour when required, maximum 4200 mg/day
Secondary options
diphenoxylate/atropine: 5 mg orally four times daily initially, followed by 2.5 to 5 mg twice to four times daily when required, maximum 20 mg/day
More diphenoxylate/atropineDose refers to diphenoxylate component.
Drug choice, dose and interactions may be affected by the patient's comorbidities. Check your local drug formulary.
Show drug information for a patient with no comorbidities
Primary options
loperamide
OR
bismuth subsalicylate
Secondary options
diphenoxylate/atropine
Choose a patient group to see our recommendations
Please note that formulations/routes and doses may differ between drug names and brands, drug formularies, or locations. Treatment recommendations are specific to patient groups. See disclaimer
Use of this content is subject to our disclaimer