Viral gastroenteritis in adults

Overview 
Theory 
Diagnosis 
Management 
Follow up 
Resources 

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

ACUTE

mild to moderate dehydration

1st line – oral rehydration

Back

1st line –

oral rehydration

Most patients manage themselves at home. Older, frail or immunocompromised patients may need more active treatment and monitoring.

Assess hydration status to determine the immediate management. Initial treatment is to prevent or treat dehydration.[23]

In patients with no indication of requiring intravenous fluid resuscitation, initiate oral rehydration. See our section on severe dehydration in the table below for indicators of severe dehydration that may require urgent fluid resuscitation.
Mild and uncomplicated viral gastroenteritis, where the patient has no sign of dehydration, can be safely treated by the patient at home.[17][22] Advise the patient to maintain an adequate fluid intake to prevent dehydration.[22]
In the community, explain that the patient should return for a follow-up appointment or present to the emergency department if:[22]
- Their symptoms do not improve within 48 hours
- Their symptoms worsen
- Severe vomiting or dehydration, persistent fever, abdominal distension, or frank blood in stools develop.

Replace fluid and electrolytes lost through diarrhoea by giving solutions containing sodium, potassium, and glucose (or another carbohydrate).[26] Older patients or those with comorbidities may be at increased risk from the effects of dehydration and may require intravenous fluids.[23]

In patients in need of rehydration:

Use a reduced osmolarity oral rehydration solution (50-60 mmol/L [50-60 mEq/L] sodium) as the first-line treatment for mild to moderate dehydration in adults with acute or severe diarrhoea from any cause[3][17][19]
Rehydrate the patient over 3 to 4 hours (except in hypernatraemic dehydration, in which case rehydration should occur more slowly over 12 hours)[26]
Reassess the patient after initial rehydration. Continue with rapid fluid replacement if the patient is still dehydrated[26]
Avoid fluids high in sugar and very low in sodium (such as some fruit juices) as these may exacerbate diarrhoea[17]
Once rehydrated, prevent further dehydration by encouraging the patient to drink normal volumes of an appropriate fluid and by replacing continuing losses with an oral rehydration solution.[26]

Oral rehydration solution should enhance the absorption of water and electrolytes, and replace the electrolyte deficit adequately and safely.[26]

It contains an alkalinising agent to counter acidosis and is slightly hypo-osmolar (about 250 mmol/L) to prevent the possible induction of osmotic diarrhoea.[26]

The World Health Organization (WHO) oral rehydration salts formulation contains:[26]

Sodium chloride 2.6 g
Potassium chloride 1.5 g
Sodium citrate 2.9 g
Anhydrous glucose 13.5 g.

It is dissolved in sufficient water to produce 1 L (providing sodium 75 mmol/L, potassium 20 mmol/L, chloride 65 mmol/L, citrate 10 mmol/L, glucose 75 mmol/L).

This formulation is recommended by the WHO and the United Nations Children's fund, but it is not commonly used in the UK. In the UK, formulations are lower in sodium (50-60 mmol/L [50-60 mEq/L]) than the WHO formulation, because the sodium loss is usually less severe.[26]

Practical tip

Fluid challenge with a syringe or straw. Give the fluid slowly: for example, 10 mL over 10 minutes. See whether the patient can tolerate it for an hour. This will test whether the patient can tolerate oral fluids and reassure the patient if they can retain the fluid.

The patient should eat as and when they feel able to. Restricted diets are unnecessary.[17]

Normal feeding should continue for patients with no dehydration and can resume immediately after correction of dehydration if present.[17]

In patients requiring hospitalisation, the patient can be discharged if they can tolerate oral fluids, providing that they are well and that electrolyte disturbances have been resolved.

Consider – anti-emetic

Back

Consider –

anti-emetic

Additional treatment recommended for SOME patients in selected patient group

Do not routinely use anti-emetics. They are not usually necessary and may have an adverse effect of masking symptoms.[23]

In patients with mild or moderate volume depletion, consider anti-emetics only for those with intractable vomiting and who are unable to tolerate oral fluids.

Cyclizine or ondansetron are usually considered first-line options. Metoclopramide is another option, but has an increased risk of adverse effects.

The risk of neurological effects with metoclopramide, such as tardive dyskinesia and extrapyramidal disorders, outweighs the benefits with long-term use or with high doses. Only prescribe the recommended dose (maximum 30 mg/day) for short-term use (up to 5 days).[33]

Primary options

ondansetron: 4-8 mg orally twice daily

cyclizine: 50 mg orally up to three times daily

Secondary options

metoclopramide: body weight <60 kg: up to 500 micrograms/kg/day orally given in 3 divided doses; body weight ≥60 kg: 10 mg orally up to three times daily

Consider – antidiarrhoeal

Back

Consider –

antidiarrhoeal

Additional treatment recommended for SOME patients in selected patient group

Do not routinely use antidiarrhoeals.[23]

In practice, antidiarrhoeals, such as loperamide, may rarely be used as a specific strategy for short-term symptom management: for example, if a patient has to travel.

Antidiarrhoeals are not usually necessary and may have an adverse effect of masking symptoms.[23]

Avoid antidiarrhoeals in patients with bloody diarrhoea (which may indicate a bacterial cause) or where an inflammatory cause is suspected, as it may prolong the infection.[13]
- Intestinal motility promotes clearance of infecting bacterial pathogens, such as Salmonella, Shigella, Escherichia coli, and Clostridium difficile. If this clearance is prohibited, the bacteria may proliferate and penetrate the epithelium, leading to a worse clinical outcome.[34]
In particular, the pathogenesis of C difficile disease is mediated by toxins. Decreased intestinal peristalsis caused by antimotility agents may allow for increased contact time between organisms such as C difficile, the toxins produced, and the mucosal epithelium.[34]

Primary options

loperamide: 4 mg orally initially, followed by 2 mg after each loose stool, maximum 16 mg/day for up to 5 days

severe dehydration or unable to tolerate oral fluids

1st line – intravenous fluids

Back

1st line –

intravenous fluids

Assess hydration status to determine the immediate management. Initial treatment is to prevent or treat dehydration.[23]

Use intravenous fluids for patients with severe dehydration, or in patients unable to tolerate oral fluids.

In rare cases, patients may present with shock. See our topic Shock for management recommendations.

Indicators that the patient may need urgent fluid resuscitation include:[14]

Systolic blood pressure less than 100 mmHg
Heart rate more than 90 beats per minute
Cold peripheries
Respiratory rate more than 20 breaths per minute
National Early Warning Score (NEWS2) National Early Warning Score (NEWS) 2 Opens in new window of 5 or more.

Patients who develop viral gastroenteritis while in hospital, particularly those who are old and frail, may be started on intravenous fluids, with regular monitoring, at an earlier stage.

Check local protocols for specific recommendations on fluid choice.

Latest evidence suggests a balanced crystalloid (such as Hartmann's solution, Ringer's lactate, or PlasmaLyte) may have marginal benefits compared with normal saline, although either choice of fluid is reasonable.[31]

Use an intravenous fluid management plan with details of the fluid and electrolyte prescription over the next 24 hours, plus plans for assessment and monitoring. This should be reviewed by an expert daily.[14]

Regularly monitor patients receiving intravenous fluids.[14]

Clinical monitoring should include current status of:
- NEWS2 score National Early Warning Score (NEWS) 2 Opens in new window
- Fluid balance charts
- Weight.
Laboratory investigations should include:
- Full blood count
- Urea
- Creatinine
- Electrolytes.

Seek expert help if patients have a complex fluid and/or electrolyte redistribution issue or imbalance, or a significant comorbidity, such as:[14]

Gross oedema
Sepsis
Hyponatraemia or hypernatraemia
Renal, liver, and/or cardiac impairment
Post-operative fluid retention and redistribution
Malnourishment and refeeding issues.

Evidence: Choice of fluid

A balanced crystalloid may have marginal benefits compared with normal saline for intravenous fluid administration in critically ill adults.

A 2018 US multicentre cluster-randomised trial among 15,802 critically ill adults receiving care in the intensive care unit found small benefits from balanced crystalloid compared with saline.

The 30-day outcomes showed 10.3% mortality in the balanced crystalloid group versus 11.1% in the saline group (P = 0.06) and a major adverse kidney event rate of 14.3% versus 15.4% in the two groups, respectively (marginal odds ratio 0.91, 95% CI 0.84 to 0.99).[31]

The National Institute for Health and Care Excellence guidelines on intravenous fluid therapy in adults in hospital recommend that for patients in need of intravenous fluid resuscitation, use a crystalloid containing sodium in the range 130 to 154 mmol/L (130-154 mEq/L), which encompasses normal saline or a balanced crystalloid.[14]

The patient can be discharged once they can tolerate oral fluids, providing that they are well and that electrolyte disturbances have been resolved.

The patient should eat as and when they feel able to. Restricted diets are unnecessary.[17]

Normal feeding should continue for patients with no dehydration and can resume immediately after correction of dehydration if present.[17]

Consider – anti-emetic

Back

Consider –

anti-emetic

Additional treatment recommended for SOME patients in selected patient group

Do not routinely use anti-emetics. They are not usually necessary and may have an adverse effect of masking symptoms.[23]

Consider using in patients on intravenous fluids when required for symptomatic relief.

Cyclizine or ondansetron are usually considered first-line options. Metoclopramide is another option, but has an increased risk of adverse effects.

The risk of neurological effects with metoclopramide, such as tardive dyskinesia and extrapyramidal disorders, outweighs the benefits with long-term use or with high doses. Only prescribe the recommended dose (maximum 30 mg/day) for short-term use (up to 5 days).[33]

Primary options

ondansetron: 4-8 mg orally/intravenously/intramuscularly every 12 hours

cyclizine: 50 mg orally/intravenously/intramuscularly every 8 hours

Secondary options

metoclopramide: body weight <60 kg: up to 500 micrograms/kg/day orally/intravenously/intramuscularly given in 3 divided doses; body weight ≥60 kg: 10 mg orally/intravenously/intramuscularly up to three times daily

Consider – antidiarrhoeal

Back

Consider –

antidiarrhoeal

Additional treatment recommended for SOME patients in selected patient group

Do not routinely use antidiarrhoeals.[23]

In practice, antidiarrhoeals, such as loperamide, may be used as a specific strategy for short-term symptom management: for example, if a patient has to travel.

They are not usually necessary and may have an adverse effect of masking symptoms.[23]

Avoid antidiarrhoeals in patients with bloody diarrhoea (which may indicate a bacterial cause) or where an inflammatory cause is suspected, as it may prolong the infection.[13]
- Intestinal motility promotes clearance of infecting bacterial pathogens, such as Salmonella, Shigella, Escherichia coli, and Clostridium difficile. If this clearance is prohibited, the bacteria may proliferate and penetrate the epithelium, leading to a worse clinical outcome.[34]
In particular, the pathogenesis of C difficile disease is mediated by toxins. Decreased intestinal peristalsis caused by antimotility agents may allow for increased contact time between organisms such as C difficile, the toxins produced, and the mucosal epithelium.[34]

Primary options

loperamide: 4 mg orally initially, followed by 2 mg after each loose stool, maximum 16 mg/day for up to 5 days

Use of this content is subject to our disclaimer

Viral gastroenteritis in adults

mild to moderate dehydration

oral rehydration

Practical tip

anti-emetic

Primary options

Secondary options

These drug options and doses relate to a patient with no comorbidities.

Primary options

Secondary options

Drug choice, dose and interactions may be affected by the patient's comorbidities. Check your local drug formulary.

Primary options

Secondary options

antidiarrhoeal

Primary options

These drug options and doses relate to a patient with no comorbidities.

Primary options

Drug choice, dose and interactions may be affected by the patient's comorbidities. Check your local drug formulary.

Primary options

severe dehydration or unable to tolerate oral fluids

intravenous fluids

Evidence: Choice of fluid

anti-emetic

Primary options

Secondary options

These drug options and doses relate to a patient with no comorbidities.

Primary options

Secondary options

Drug choice, dose and interactions may be affected by the patient's comorbidities. Check your local drug formulary.

Primary options

Secondary options

antidiarrhoeal

Primary options

These drug options and doses relate to a patient with no comorbidities.

Primary options

Drug choice, dose and interactions may be affected by the patient's comorbidities. Check your local drug formulary.

Primary options

Viral gastroenteritis in adults

Treatment algorithm

mild to moderate dehydration

oral rehydration

Practical tip

anti-emetic

Primary options

Secondary options

These drug options and doses relate to a patient with no comorbidities.

Primary options

Secondary options

Drug choice, dose and interactions may be affected by the patient's comorbidities. Check your local drug formulary.

Primary options

Secondary options

antidiarrhoeal

Primary options

These drug options and doses relate to a patient with no comorbidities.

Primary options

Drug choice, dose and interactions may be affected by the patient's comorbidities. Check your local drug formulary.

Primary options

severe dehydration or unable to tolerate oral fluids

intravenous fluids

Evidence: Choice of fluid

anti-emetic

Primary options

Secondary options

These drug options and doses relate to a patient with no comorbidities.

Primary options

Secondary options

Drug choice, dose and interactions may be affected by the patient's comorbidities. Check your local drug formulary.

Primary options

Secondary options

antidiarrhoeal

Primary options

These drug options and doses relate to a patient with no comorbidities.

Primary options

Drug choice, dose and interactions may be affected by the patient's comorbidities. Check your local drug formulary.

Primary options