Antidiarrheal
Antidiarrheals are a class of medication used primarily to manage and reduce the frequency of diarrhea. This class of medication predominantly works by slowing digestion, reducing fluid loss, or improving absorption. There are four main classes: opiates, 5-HT3 receptor antagonists, adsorbents, and bulk-forming agents. Commonly used medications include loperamide, diphenoxylate, bismuth subsalicylate, Cholestyramine, and Octreotide. Although not considered an antidiarrheal, oral rehydration solutions are also an important aspect of managing diarrhea.
Medical use
Acute diarrhea
Acute diarrhea is a common condition that typically resolves on its own with oral rehydration therapy. Most cases of acute diarrhea are caused by infections from contaminated food or water and usually go away on their own within a week. The most common causes of acute diarrhea in children are the viral agents norovirus and rotavirus, accounting for about 70% of cases. Travelers’ diarrhea is one of the most common illnesses affecting people of all ages abroad, with up to 70% of travelers developing symptoms within two weeks. While traditional advice like avoiding uncooked or unpeeled foods was once thought to be effective, poor sanitation and food handling practices—especially in local eateries—remain major risk factors.Anti-motility medications like loperamide and diphenoxylate can help manage the symptoms of travelers’ diarrhea by reducing the frequency of bowel movements, which can be helpful when needing to travel, but are not curative. Loperamide and diphenoxylate should be avoided in people with bloody diarrhea or a fever, and loperamide is typically not recommended for children under six. Additionally, zinc supplements, particularly in children, can reduce diarrheal duration by up to 25% and reduce stool volume by up to 30%.
Dehydration and oral replacement therapy
The primary risk from diarrhea is dehydration and electrolyte loss, making fluid and electrolyte replacement the top treatment priority. Drinking fluids orally is typically as effective as IV fluids and more cost-efficient for most patients. Thus, rehydration is essential when managing acute diarrhea, especially in vulnerable groups like young children, older adults, and those with chronic conditions. Oral rehydration solutions are made with clean water, salt, and sugar. These solutions are ideal for severe cases, while milder dehydration can be managed with safe, preferred fluids—though overly sugary drinks should be avoided.Dehydration is categorized into three levels: severe, some, or none. Severe dehydration includes signs like lethargy, sunken eyes, little to no urine output, and confusion. Some dehydration may present with dry mouth, restlessness, thirst, and slightly sunken eyes. If these signs are absent or insufficient, the person is not considered dehydrated.