Diarrhea Medication

Updated: Jan 31, 2020
  • Author: Stefano Guandalini, MD, AGAF; Chief Editor: Carmen Cuffari, MD  more...
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Medication Summary

Diarrheal diseases have been the object of numerous forms of treatment, both dietetic and pharmacologic, for centuries. However, the evidence is now clear that, in most cases, the best option for treatment of acute-onset diarrhea is the early use of oral rehydration therapy (ORT). [1] Pharmacological treatment is rarely of any use, and antidiarrheal drugs are often harmful.

In terms of recommended antimicrobial treatment in the immunocompetent host, enteric bacterial and protozoan pathogens can be grouped as follows:

Agents for whom antimicrobial therapy is always indicated: The consensus includes only V cholerae, Shigella species, and G lamblia.

Agents for whom antimi­crobial therapy is indicated only in selected circumstances, include the following:

  • Infections by enteropathogenic E coli, when running a prolonged course

  • Enteroinvasive E coli, based on the sero­logic, genetic, and pathogenic similarities with Shigella

  • Yersinia infections in subjects with sickle cell disease

  • Salmonella infections in very young infants, if febrile or with positive blood culture findings


Recently, some strains of probiotics (defined as live microorganisms that when ingested in adequate doses, provide a benefit to the host) have been found to be effective as an adjunct when treating children with acute diarrhea. Data from well-conducted randomized controlled trials on efficacy of probiotics in children with diarrhea are definitely positive. They consistently show a statistically significant benefit and moderate clinical benefit of a few, now well-identified probiotic strains (mostly Lactobacillus GG and Saccharomyces boulardii but also Lactobacillus reuteri) in the treatment of acute watery diarrhea (primarily rotaviral) in infants and young children in developed countries.

Such a beneficial effect seems to result in a reduction of the duration of diarrhea of about one day and seems to be exerted mostly on rotaviral diarrhea, with much less evidence of efficacy in invasive bacterial diarrhea. The effect is not only strain-dependent but also dose-dependent, with doses of at least 5 billion/d being required for effect. [14] Shortening the duration of diarrhea by one day may not appear to be hugely beneficial. However, in consideration of the high morbidity of the infection, even a reduction of this order is indeed desirable because it affords considerable savings in terms of loss of working days and direct health costs.

Furthermore, probiotics may reduce the risk of spreading rotavirus infection by shortening diarrhea duration and volume of watery stool output and by reducing the fecal shedding of rotavirus, and they have been found useful in preventing the dissemination of hospital-acquired diarrheas.

A recent position paper jointly published by the ESPGHAN and the European Society for Pediatric Infectious Disease (ESPID) stated, ‘‘Probiotics may be an effective adjunct to the management of diarrhea. However, because there is no evidence of efficacy for many preparations, we suggest the use of probiotic strains with proven efficacy and in appropriate doses for the management of children with acute gastroenteritis as an adjunct to rehydration therapy (II, B). The following probiotics showed benefit in meta-analyses of randomized controlled trials: Lactobacillus GG (I, A) and S boulardii (II, B).’’

Table 5 illustrates current assessment of the efficacy of probiotics in conditions characterized by diarrhea.

Table 5. Probiotic Efficacy in Diarrhea (Open Table in a new window)


Patients and Controls

Most-Studied Probiotics

Evidence of Efficacy

(- to +++)

Prevention of Daycare Diarrhea


Lactobacillus GG

Bifidobacterium lactis

Lactobacillus reuteri

Lactobacillus casei

Bifidobacterium bifidum + Streptococcus thermophilus


Prevention of Nosocomial Diarrhea


Lactobacillus GG


Prevention of Antibiotic-Associated Diarrhea


Lactobacillus GG

Saccharomyces boulardii


Infectious Diarrhea


Lactobacillus GG

Saccharomyces boulardii


Persistent Diarrhea


Lactobacillus GG




Antibiotic and antiparasitics agents

Class Summary

Antimicrobial agents, in addition to the immune system, help destroy offending organisms. Their use is confined to specific etiologies and/or clinical circumstances.

Cefixime (Suprax)

Potent long-acting oral cephalosporin with increased gram-negative coverage. Inhibits bacterial cell wall synthesis by binding to 1 or more PBPs. Bacteria eventually lyse because of ongoing activity of cell wall autolytic enzymes while cell wall assembly is arrested.

Ceftriaxone (Rocephin)

A third-generation cephalosporin antibiotic with activity against gram-positive and some gram-negative bacteria. Binds to PBPs, inhibiting bacterial cell wall growth.

Cefotaxime (Claforan)

Third-generation cephalosporin antibiotic with activity against gram-positive and some gram-negative bacteria. Binds to PBPs, inhibiting bacterial cell wall growth.

Erythromycin (E.E.S., E-Mycin, Eryc, Ery-Tab, Erythrocin)

Bacteriostatic macrolide with activity against most gram-positive organisms and atypical respiratory organisms. Useful for Campylobacter species and vibrio enteritis.

Furazolidone (Furoxone)

Antiparasitic agent with wide coverage. Nitrofuran with antiprotozoal activity. Alternative drug for children because availability in liquid suspension. Most common adverse effects are GI upset and brown discoloration of urine.

Iodoquinol (Vytone, Yodoxin)

Antiparasitic agents with wide coverage.

Metronidazole (Flagyl)

Very active against Giardia species, gram-negative anaerobes, and Entamoeba species. Imidazole ring-based antibiotic active against various anaerobic bacteria and protozoa. Often used in combination with other antimicrobial agents except for C difficile enterocolitis).

Paromomycin (Humatin)

Amebicidal and antibacterial aminoglycoside obtained from a strain of Streptomyces rimosus, active in intestinal amebiasis. Recommended for treatment of Diphyllobothrium latum, Taenia saginata, T solium, Dipylidium caninum, and Hymenolepis nana.

Quinacrine (Atabrine)

Very effective antiparasitic against Giardia species.

Sulfamethoxazole and trimethoprim (Bactrim, Septra, Cotrim)

Folate-synthesis blocker with wide antibiotic coverage. Inhibits bacterial growth by inhibiting synthesis of dihydrofolic acid. Effective in E coli infections. Dosage form contains 5:1 ratio of sulfamethoxazole to trimethoprim.

Vancomycin (Vancocin)

Effective treatment (when PO) for antibiotic-associated colitis due to C difficile. However, reserve for individuals whose symptoms are not responding to less expensive and almost equally effective metronidazole.

Tetracycline (Sumycin)

Treats gram-positive and gram-negative organisms as well as mycoplasmal, chlamydial, and rickettsial infections. Good agent in older children who present with severe Yersinia species infection.

Nitazoxanide (Alinia)

Inhibits growth of C parvum sporozoites and oocysts and G lamblia trophozoites. Elicits antiprotozoal activity by interfering with pyruvate-ferredoxin oxidoreductase (PFOR) enzyme-dependent electron transfer reaction, which is essential to anaerobic energy metabolism. Available as a 20-mg/mL oral susp.

Rifaximin (Xifaxan, RedActiv, Flonorm)

Nonabsorbed (< 0.4%), broad-spectrum antibiotic specific for enteric pathogens of the gastrointestinal tract (ie, Gram-positive, Gram-negative, aerobic and anaerobic). Rifampin structural analog. Binds to beta-subunit of bacterial DNA-dependent RNA polymerase, thereby inhibiting RNA synthesis. Indicated for E coli (enterotoxigenic and enteroaggregative strains) associated with travelers' diarrhea.



Class Summary

These agents elicit active immunization to increase resistance to infection. Vaccines consist of microorganisms or cellular components, which act as antigens. Administration of the vaccine stimulates the production of antibodies with specific protective properties.

Rotavirus vaccine (RotaTeq, Rotarix)

Currently, 2 PO administered live-virus vaccines are marketed in the United States. Both are indicated to prevent rotavirus gastroenteritis, a major cause of severe diarrhea in infants.

RotaTeq is a pentavalent vaccine that contains 5 live reassortant rotaviruses and is administered as a 3-dose regimen against G1, G2, G3, and G4 serotypes, the 4 most common rotavirus group A serotypes. It also contains attachment protein P1A (genotype P[8]).

Rotarix protects against rotavirus gastroenteritis caused by G1, G3, G4, and G9 strains and is administered as a 2-dose series in infants aged 6-24 wk.

Clinical trials found that the vaccines prevented 74-78% of all rotavirus gastroenteritis cases, nearly all severe rotavirus gastroenteritis cases, and nearly all hospitalizations.