Viral gastroenteritis, commonly known as “stomach flu,” is characterized as an inflammation of the lining of the stomach, small intestine, and large intestine. It is highly contagious and accounts for a significant number of both diarrhea and dehydration cases.1-4 Viral gastroenteritis is frequently transmitted via contaminated food or water, contaminated objects, or another person infected with the virus.1,2

Although many viruses can cause gastroenteritis, the most common ones include norovirus and rotavirus; other less common causes include adenovirus, astrovirus, and hepatitis A.1-3 Norovirus is the most frequent cause of diarrhea in adults and the second most common cause in the pediatric population.1-3 Norovirus also accounts for more than 90% of epidemic viral gastroenteritis cases, and outbreaks of norovirus gastroenteritis typically occur among restaurant patrons, on cruise ships, in schools, among hospital patients, among residents in long-term care facilities, and in immunocompromised patients.1

In the pediatric population, rotavirus causes an estimated 80% of viral gastroenteritis cases in those 5 years and younger.1,5 Rotavirus also tends to occur seasonally, between November and February, and is typically spread via fecal-oral transmission and is contagious.1-4



Symptoms of viral gastroenteritis most often manifest within 4 to 48 hours after contact with the virus.1-4 The most common signs and symptoms associated with viral gastroenteritis can vary from patient to patient and may range from mild to severe (Table 1).1-4 Self-treatment should be limited to individuals who are otherwise healthy and have mild to moderate symptoms.1 Because dehydration is the most common complication of viral gastroenteritis due to episodes of diarrhea and vomiting, patients—especially young children, older adults, and those with compromised immune systems—should be monitored closely and be advised to seek medical care immediately if exhibiting signs of severe dehydration (Table 2) to prevent complications.1-4



Pharmacists are in a pivotal position to guide patients on the proper use of the various nonprescription agents that may help alleviate some of the symptoms associated with viral gastroenteritis. They can also help ascertain if self-treatment is appropriate and recommend further medical care if warranted, especially when the patient is a young child, an elderly patient, or an individual who has preexisting medical conditions or is exhibiting signs of severe dehydration.
 
Managing Gastroenteritis
In general, the majority of cases of viral gastroenteritis resolve with symptomatic management and without complications. The goals of therapy are to prevent or correct fluid and electrolyte loss, control symptoms, and identify possible cause.1 The American Academy of Pediatrics devised and published practice guidelines for the management of acute gastroenteritis in children and recommend using the following criteria to evaluate the degree of dehydration: blood pressure, pulse, heart rate, skin turgor, fontanelle, mucous membranes, eyes, extremities, mental status, urine output, and thirst.4,5 Other guidelines from the American Academy of Pediatrics include the following4:
  • The treatment of rotavirus diarrhea is based chiefly on replacing fluids and electrolytes, as directed by the estimated degree of dehydration.
  • Oral rehydration therapy is recommended for preventing and treating early dehydration and continued replacement therapy for ongoing losses.
  • Age-appropriate diets should be continued in children with diarrhea who are not dehydrated. When mild to moderately dehydrated children are rehydrated, resume age-appropriate diet.
  • Those exhibiting signs of severe dehydration should be treated with intravenous fluids.
  • Administering antiemetic and antidiarrheal agents to small children is not recommended.4
Oral Rehydration Products
To manage or prevent dehydration, patients may elect to use any of the various oral rehydration OTC products that typically contain the electrolytes sodium, potassium, and chloride.1 Many products are available as premixed, ready-to-use solutions, whereas some are available as powders or effervescent tablets to be reconstituted with water. Patients should also be encouraged to sip on liquids such as water, chicken broth, or ginger ale and eat ice chips as tolerated every 30 to 60 minutes to prevent dehydration.1,2 Patients should be advised to avoid drinking fruit juice because juices may exacerbate diarrhea in some patients.1,2
 


Antidiarrheal Products
Although the diarrhea associated with most cases of mild to moderate viral gastroenteritis is self-limiting, some patients may elect to use the various nonprescription anti-diarrheals on the market for symptom control; however, these agents are not recommended for use in children unless recommended by a pediatrician or health care provider.1
 


Loperamide
Loperamide is classified as a synthetic opioid agonist that lacks central nervous system effects because it is a substrate for P-glycoprotein.1,6 It is indicated for the treatment of acute nonspecific diarrhea, traveler’s diarrhea, and chronic diarrhea associated with irritable bowel syndrome.1,6 Loperamide is not recommended for individuals under 6 years of age, except under the supervision of primary care provider.1 The most common adverse effects include dizziness and constipation.1,6
 
Bismuth Subsalicylate
Bismuth subsalicylate is approved for the management of acute diarrhea, including traveler’s diarrhea, in adults and children 12 years and older and should never be given to children or adolescents recovering from influenza or chicken pox.1 Patients should be advised to not take bismuth subsalicylate if also taking tetracyclines, quinolones, or medications for gout.1 Patients with sensitivity to aspirin, who have a history of GI bleeding, or who take anticoagulation therapy should not take this agent either.1 During counseling, patients should be advised that the use of this agent may cause a dark discoloration of the tongue and stool.1
 
Counseling Patients
For the majority of patients, symptoms classically resolve within a few days, but pharmacists can be instrumental in assisting patients with viral gastroenteritis. During counseling, pharmacists can provide patients and caregivers with essential information regarding viral gastroenteritis, including the proper use of oral rehydration products, anti-diarrheals, as well as nonpharmacologic self-measures for symptomatic relief. These include maintaining hydration, monitoring for signs of dehydration, getting rest, and gradually beginning to eat bland, easy-to-digest foods such as crackers, toast, gelatin, and bananas when able to tolerate.1,2 Pharmacists can also provide patients and caregivers with information regarding the various preventative measures that may reduce or prevent the transmission of viral gastroenteritis, such as properly handling foods, especially raw foods and uncooked meat; washing hands thoroughly with warm water and soap several times a day, especially after using the toilet; avoiding contact with infected persons when possible; and disinfecting hard surfaces to avoid transmission of the virus.2

Additionally, pharmacists can remind parents and caregivers that the CDC recommends that infants older than 2 months obtain the rotavirus vaccination to protect against the rotavirus.2,7 Parents and caregivers should be advised to immediately seek medical care if a patient is younger than 6 months, does not show any signs of improvement, shows that symptoms are worsening, has a fever >102, exhibits signs of severe dehydration (especially children and elderly patients), is unable to tolerate oral fluids, or has blood or mucous in the stool.1-4 Moreover, pregnant women, elderly patients, individuals with preexisting medical conditions, and infants should always be evaluated by their primary health care provider to avoid complications.1
 
Ms. Terrie is a clinical pharmacist and medical writer based in Haymarket, Virginia.

References
  1. Walker P. Diarrhea. In: Krinsky D, Berardi R, Ferreri S, et al, eds. Handbook of Nonprescription Drugs. 18th ed. Washington, DC: American Pharmacists Association; 2015.
  2. Viral gastroenteritis (stomach flu). Medline Plus website. medlineplus.gov/ency/article/000252.htm. Accessed January 3, 2017.
  3. Viral gastroenteritis. National Institute of Diabetes and Digestive and Kidney Disease website. niddk.nih.gov/health-information/digestive-diseases/viral-gastroenteritis. Accessed January 3, 2017.
  4. Tablang V. Viral gastroenteritis. Medscape website. emedicine.medscape.com/article/176515-overview. Accessed January 3, 2017.
  5. Churgay CA. Aftab Z. Gastroenteritis in children: part 1. Diagnosis. Am Fam Physician. 2012;85(11):1059-1062.
  6. Loperamide drug Information. Medscape website. reference.medscape.com/drug/imodium-k-pek-ii-loperamide-342041#0. Accessed January 3, 2017.
  7. Vaccination. CDC website. cdc.gov/rotavirus/vaccination.html. Accessed January 3, 2017.