Gastroenteritis - Viral Drug Summary

Last updated: 19 November 2025
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Antidiarrheals

Content on this page:

Antidiarrheals

Antidiarrheals


Drug Dosage Remarks
Antidiarrheal Microorganisms
Bacillus clausii 1-2 vials of 2 billion/
5 mL suspension PO 3-4 hourly		 Special Instructions
  • Given in interval between antibiotic doses
Lactobacillus spp
(L reuteri, L acidophilus, L rhamnosus, L sporogenes)
 450 mg PO 24 hourly

Adverse Reactions

  • Lactobacillus may cause intestinal flatus

Special Instructions

  • Should be taken with food
Lyophilized 
Saccharomyces boulardii		 250 mg PO 24 hourly

Adverse Reactions

  • Dermatologic effects (rash, urticaria, pruritus); GI effects (constipation, flatulence, thirst); Other effect (angioedema)

Special Instructions

  • Contraindicated in patients with allergies to yeast and immunocompromised
  • Use with caution in patients with diarrhea of >2 days, yeast allergy, immunocompromised, or previously or currently on antibiotic therapy
Antipropulsive 
Loperamide Initial dose:
≥6 years old: 2 mg PO then 1 mg PO after every subsequent loose stool
≥12 years old: 4 mg PO then 2 mg PO after every subsequent loose stool
Max dose: 
≥6 years old: 6 mg/20 kg body weight
≥12 years old: 12 mg/day

Adverse Reactions

  • GI effects (abdominal pain, nausea, constipation, rarely paralytic ileus); Hypersensitivity reactions

Special Instructions

  • Do not use in patients with ileus, abdominal distension, acute inflammatory bowel disease, antibiotic-associated colitis, or any other condition for which inhibition of peristalsis must be avoided
  • Use with caution in patients with hepatic impairment
Antipropulsive
Loperamide Initial dose:
≥6 years old: 2 mg PO then 1 mg PO after every subsequent loose stool
≥12 years old: 4 mg PO then 2 mg PO after every subsequent loose stool
Max dose: 
≥6 years old: 6 mg/20 kg body weight
≥12 years old: 12 mg/day

Adverse Reactions

  • GI effects (abdominal pain, nausea, constipation, rarely paralytic ileus); Hypersensitivity reactions

Special Instructions

  • Do not use in patients with ileus, abdominal distension, acute inflammatory bowel disease, antibiotic-associated colitis, or any other condition for which inhibition of peristalsis must be avoided
  • Use with caution in patients with hepatic impairment
Intestinal Adsorbent
Dioctahedral smectite ≥2 years old: 6-9 g/day PO in 2-3 divided doses

Adverse Reactions

  • GI effect (rarely constipation)

Special Instructions

  • Should be taken alone and not with other drugs as it affects absorption of these substances
Other Antidiarrheal
Racecadotril 1.5 mg/kg/dose PO 8 hourly
Max dose: 6 mg/kg/day
≥3-9 months old; <9 kg: 10 mg PO 8 hourly
9-30 months old; 9-13 kg: 20 mg PO 8 hourly
30 months old-9 years old; 13-27 kg: 30 mg PO 8 hourly
>9 years old; >27 kg:
60 mg PO 8 hourly
Max duration: 7 days
To be given in combination with ORS

Adverse Reactions

  • GI effects (nausea, constipation, tongue edema, lip edema); Respiratory effect (tonsillitis); Dermatologic effects (rash, erythema, prurigo, pruritus, urticaria); Other effects (headache, drowsiness, angioedema, eyelid edema, face edema)

Special Instructions

  • Ensure adequate hydration
  • Contraindicated in patients with fructose intolerance, glucose-galactose malabsorption syndrome, or sucrose-isomaltase insufficiency
  • Use with caution in patients with bloody/purulent stool and/or fever, prolonged uncontrolled vomiting, diarrhea
Zinc-containing Preparation
Zinc 
(Zinc sulphate monohydrate, 
Zinc sulfate)		 <6 months old: 10 mg PO 24 hourly x 10 days
>6 months old-5 years old: 20 mg PO 24 hourly x 10 days 

Adverse Reactions

  • GI effects (nausea/vomiting, bitter taste, mouth irritation)

Special Instructions

  • Take at least 1 hour before or 2 hours after meals
  • May be taken with meals to reduce GI discomfort
  • Use with caution in patients at risk for renal failure

Antiviral Drug


Drug Dosage Remarks
Affinity-purified antibodies
to human interferon gamma 		 >1 month old: 
Day 1: 3 mg PO every 30 minutes within the first 2 hours, then 9 mg PO divided 3x at equal intervals
Day 2 onwards: 
3 mg PO 8 hourly until fully recovered
 Adverse Reactions
  • GI effects (nausea/vomiting, bitter taste, mouth irritation)
Special Instructions
  • Should be started as soon as possible, starting from the appearance of symptoms
  • Use with caution in patients with rare hereditary problems of galactose intolerance, lactase deficiency or glucose-galactose malabsorption

Electrolytes


Drug Dosage Remarks
Sodium chloride, Trisodium citrate, Potassium chloride, Glucose
(NaCl, KCl, Trisodium citrate, Glucose anhydrous)		 <2 years old: 
1 sachet (5.125 g) PO for the first 2 hours, then up to 8 hourly
2-5 years old: 1 sachet (5.125 g) PO 3x for the first 2 hours, then up to 4 hourly
>5 years old: 1 sachet (5.125 g) PO 4x for the first 2 hours, then up to 2 hourly
 Adverse Reactions
  • Hypernatremia, Na and water retention, nausea/vomiting
Special Instructions
  • Dissolve 1 sachet in 250 mL water
  • Use with caution in patients with renal impairment, severe dehydration, severe and prolonged diarrhea, glucose malabsorption, vomiting, inability to drink

Supplements & Adjuvant Therapy


Drug Dosage Remarks
Bovine colostrum1 ≥12 months old: 
1 sachet (7 g) PO 24 hourly x 3 days
 Special Instructions
  • Mix the contents of 1 packet with 30 mL water in a cup
  • Use with caution in patients with allergy to milk and/or egg
Lactobacillus spp
(L casei, L acidophilus,L rhamnosus, L bulgaricus)/ Bifidobacterium spp
(B breve, B infantis)/Streptococcus thermophilus1
 1 sachet (1 g) PO 24 hourly x 4-7 days
 Special Instructions
  • Contents of the sachet may be added to food/water/milk/juice
  • Use with caution in patients with allergy to fish, soya or milk
1Various combination products are available. Please see the latest MIMS for specific formulations and prescribing information.

Vaccines


Drug Dosage Remarks
Human rotavirus vaccine, live attenuated (Live attenuated rotavirus vaccine, 
Vaccine, rotavirus)		 1.5 mL/dose PO x 2 doses
2 doses should be given before 16 weeks of age and must be completed by 24 weeks of age 
First dose may be administered from the age of 6 weeks
Interval between doses should not be <4 weeks 
 Adverse Reactions
  • GI effects (diarrhea, abdominal pain, flatulence, intussusception [very rare]); Other effects (irritability, dermatitis)
Special Instructions
  • Do not dilute or mix vaccine with other vaccines or solutions
  • A single replacement dose may be given at the same vaccination visit if the child regurgitates, spits out or vomits most of the vaccine dose
  • Contraindicated in patients with allergic reaction to previous dose or to any component of the vaccine, in patients with known or suspected immunodeficiency, and those predisposed to or with history of intussusception
  • Postpone vaccination in acute severe febrile illness, diarrhea or vomiting
  • Use with caution in patients with GI illnesses, growth retardation and with immunodeficient close contacts 
Pentavalent rotavirus vaccine
(Live, oral pentavalent vaccine, rotavirus, Rotavirus vaccine, live, oral, pentavalent)

 2 mL/dose PO x 3 doses at 2, 4 and 6 months of age 
First dose is administered at 6-12 weeks of age. Subsequent 2 doses administered at 4- to 10-weeks intervals. Third dose should not be given after 32 weeks of age
 Adverse Reactions
  • GI effects (diarrhea, vomiting); Other effects (irritability, fever, bronchospasm, infections [eg otitis media, nasopharyngitis])
  • Postmarketing case reports of Kawasaki disease and intussusception (rare)
Special Instructions
  • Do not dilute or mix vaccine with other solutions
  • Replacement of dose is not recommended if the child regurgitates, spits out or vomits the vaccine
    • Remaining doses should be continued following the 3-dose series
  • Contraindicated in patients with hypersensitivity to any component of the vaccine, severe combined immunodeficiency disease, and infants predisposed to or with history of intussusception
  • Use with caution in patients who are immunocompromised or those receiving immunosuppressive therapy, patients with malignancies, growth retardation or with history of GI disorders or uncorrected congenital GI malformation that would predispose to intussusception
  • Administration is deferred for 42 days after receipt of an antibody-containing product

Disclaimer

All dosage recommendations are for children with normal renal and hepatic function unless otherwise stated. 
Not all products are available or approved for above use in all countries. 
Products listed in the Drug Summary are based on indications stated in the locally approved product monographs. 
Please refer to local product monographs in Related MIMS Drugs for country-specific prescribing information.