US Pharm. 2010;35(12):12-15. 

Diarrhea is one of the more dangerous medical conditions for which nonprescription products are sold. Its consequences can be deadly if untreated or if treated inadequately. For this reason, patients with diarrhea require more counseling from the pharmacist than is the case with other minor medical conditions for which self-care is deemed appropriate and for which OTC products are also proven to be safe and effective. 

Prevalence of Diarrhea

The prevalence of diarrhea varies greatly according to such variables as geographic region, patient age, and travel. Experts estimate that at least 5% to 7% of people suffer from acute diarrhea yearly; chronic diarrhea lasting 4 weeks or more affects 3% to 5%.1 Its impact is startling. For instance, 19% of total deaths in children globally are due to diarrhea, including almost 2 million victims under the age of 5 years.2,3 There are as many as 5 billion cases worldwide each year.4 One well-known subtype, traveler's diarrhea, affects an estimated 10 million people yearly.5 

Causes of Diarrhea

The causes of diarrhea include food intolerance, medications, laxative use/abuse, and infection. There are numerous other causes (e.g., medical conditions, such as irritable bowel syndrome), but they are beyond the scope of this article. 

Food Intolerance: The classic food intolerance resulting in diarrhea is lactose intolerance. In this case, malabsorption of ingested lactose allows it to reach the intestinal tract, where resident bacteria use it as an energy source, producing gas. Undigested lactose also exerts an osmotic pull, causing water to be retained in the bowel in greater amounts than normal, leading to diarrhea.1 Patients complaining of gas and diarrhea, especially after eating ice cream or cheese or after drinking milk, might be advised to try lactase tablets (e.g., Lactaid) prior to another ingestion. In most cases, the problem will have been present for far more than the 48-hour self-use limit for nonprescription antidiarrheals, so their place in diarrhea due to lactose intolerance is questionable. 

Dietary diarrhea may also be caused by other food intolerances, such as to peppers, onions, large amounts of spices (e.g., pepper or dill), fruits, or other vegetables.6 Ingesting excessive fiber (e.g., sunflower seeds) can produce diarrhea, as can drinking overly salted beverages. Highly osmotic enteral diets are also causal.1 Continuing to ingest the causal agent and taking nonprescription antidiarrheals to help treat the resultant diarrhea is not the best course of action; rather, the causative agent should be avoided once it has been identified. 

Some parents notice that their children suffer from diarrhea late into the night of October 31. This “Halloween diarrhea” is a long--recognized result of ingesting candy containing sorbitol and fructose, two incompletely absorbed carbohydrates.7,8 The problem is usually self-limiting, but nonprescription antidiarrheals may provide a measure of comfort. 

Medications: A long list of medications can induce diarrhea. It includes antibiotics (e.g., amoxicillin/clavulanate, cephalosporins, clindamycin, tetracyclines), antihypertensives (e.g., diuretics), chemotherapeutic agents, colchicine, digitalis, nonsteroidal anti-inflammatory drugs (NSAIDs), metformin, protease inhibitors, potassium, proton pump inhibitors (PPIs), propranolol, caffeine, theophylline, and quinidine.1,6 When prescription medications are suspected to be causal, the pharmacist should suggest that the patient visit his or her practitioner for a reevaluation of the medication regimen, explaining that the diarrhea is troublesome. Diarrhea can be caused by magnesium in nonprescription antacids containing magnesium hydroxide and also by Milk of Magnesia, even when they are taken in normal antacid doses.6 Antacids containing calcium carbonate are better alternatives. Unproven herbals such as St. John's wort may also cause diarrhea. As these products are not FDA approved, their use should be halted.

Laxative Misuse/Abuse: Laxative misuse and abuse can cause acute and chronic diarrhea. Adolescent girls are especially prone to experience this as a result of anorexia and bulimia.6 Use of laxatives is only one part of the patient's multipronged efforts to prevent weight gain. The patient may complain of diarrhea, or her parents may ask for assistance. The parents may have discovered empty packages of stimulant laxatives in the child's belongings or hidden surreptitiously in the household trash. There are also cases of a parent (usually the mother) who administers laxatives to an infant or toddler to gain attention, a variant of Munchausen syndrome known as Polle syndrome (also Munchausen syndrome by proxy or pediatric condition falsification). The problem may not resolve until the court orders a separation of the parent/caregiver from the child.6 In cases of known or suspected laxative abuse, the remedy is cessation of abuse and intense counseling rather than use of nonprescription antidiarrheals. 

Infection: Infection is a major cause of acute and chronic diarrheas, including traveler's diarrhea. The causes are parasites, bacteria, or viruses.9 The body is protected against oral ingestion of diarrheagenic organisms by a gastric pH above 4, which destroys most organisms within 30 minutes of their ingestion.6 Infection results when patients ingest a quantity that overloads natural defenses (e.g., 108 for Escherichia coli). The risk of infectious diarrhea is greater if the patient is taking medications that reduce stomach acidity, such as antacids, histamine-2 (H2) blockers, or PPIs. Medications that slow peristalsis (e.g., opiates) inhibit elimination of the pathogens and may not be the best therapeutic choice. 

Patients may contract infections from parasites such as Giardia lamblia or Entamoeba histolytica through ingesting food or water contaminated with animal or human feces that contain their cysts.6 A typical scenario is that of hikers who discover a clear mountain stream and assume that the water is safe to drink. The problem is that deer, beavers, and other wild animals have done the same thing, leaving their droppings close enough that they get washed into the water. Children may also acquire G lamblia in daycare from other infants wearing leaking diapers that leave fecal residue behind. Other children may crawl through the residue, subsequently placing contaminated fingers and hands into their mouths. 

Most cases of bacterial diarrhea are contracted through ingesting contaminated food or drink, although direct fecal-oral contact and sexual spread can also occur. The pharmacist might ask about food that did not smell or taste right, although contamination in food is often not detectable through smell or taste. It might be helpful to discover if the patient recently attended an unusual event such as a potluck dinner or fundraiser where people untrained in preparation of large amounts of food attempted to do so.6 In one case with which the author is familiar, a large quantity of hot chicken was placed in a refrigerator for the next day's activities. However, the refrigerator was inadequate to cool the large amount of food overnight, and its spoilage was evident when it was removed for serving. If this had not been noticed and the food had been served, a great number of cases of bacterial diarrhea might have developed. 

Of the viral diarrheas, rotavirus and Norwalk virus are the first and second most common causes of viral gastroenteritis, respectively.6 These types seldom require more than electrolyte replacement, as they are most often self-limiting and resolve without serious sequelae. 

Nonprescription Treatment for Diarrhea

As discussed in this month's Patient Information, only two active ingredients are considered to be safe and effective for self-care of diarrhea--loperamide (e.g., Imodium A-D) and the adsorbent bismuth subsalicylate (e.g., Pepto-Bismol).6 When counseling patients, it is vital to ascertain the time that has elapsed since the first loose stool. Self-care is only safe and effective for acute diarrhea that has lasted for no more than 48 hours.6 Chronic diarrhea cannot be safely self-treated. The CDC defines chronic diarrhea as a condition wherein loose stools have persisted for more than 2 weeks, far in excess of the safe 48-hour use limit for nonprescription products.9 

It is also critical to ask about the age of the patient. The pharmacist must not assume that the person asking the questions is the patient, as it may be an infant for whom treatment is sought. While loperamide is safe for those 6 years of age and above, bismuth subsalicylate is only considered safe for self-use in patients aged 12 years and over. Products do not carry labeling for patients below those ages. Pharmacists should refrain from issuing opinions about safe doses, such as informing patients that one-half of the dose of loperamide for a 6-year-old would probably be safe for a 3-year-old. Any doses created on the spot are medically unsupported and could lead to unwanted toxicity and the potential for legal liability. If the pharmacist notices old dosing charts for OTC Imodium A-D (published by McNeil in 1993), they should be discarded, as the doses (down to 2 years of age) are not FDA approved for pharmacist-assisted self-care.10 

Nonprescription antidiarrheals carry a host of additional labeling to ensure safe use.11-13 For instance, they warn against use if the patient has fever (over 101˚F in the case of Imodium A-D), mucus in the stools, or bloody or black stools. These problems may indicate the presence of bacterial or viral gastroenteritis, irritable bowel syndrome, ulcerative colitis, or other serious medical conditions. 

Short-term use of loperamide presents little worry regarding drug interactions. Labels warn patients to consult with a pharmacist or physician if they are taking antibiotics, but this pertains to a concern that the diarrhea may have been induced by antibiotics.12 

Products containing bismuth subsalicylate must carry a drug interaction label warning patients to consult with the pharmacist or physician if they are taking any medication for anticoagulation, diabetes, gout, or arthritis. It also warns against use if the patient is taking other salicylates, is allergic to aspirin, or has an ulcer, a bleeding problem, or bloody and/or black stools. In those cases, the pharmacist should suggest that the patient use loperamide as a safer alternative product.11 

Patients purchasing both ingredients are advised to cease use if symptoms worsen, if they develop abdominal swelling (loperamide only), or if they experience tinnitus or hearing loss (bismuth subsalicylate only).11-13 Bismuth subsalicylate products also warn about the occurrence of Reye's syndrome. 

While it is common to have several bouts of diarrhea during an average year, when it lasts for more than a few days, it can cause loss of fluid and electrolytes (e.g., potassium) that leads to dehydration and serious medical problems. For this reason, it is critical to understand the limitations of what you can do about diarrhea before you seek care from a physician. 

How Long Can You Treat Diarrhea?

A close look at the labels of nonprescription products for diarrhea will reveal that the products are not to be used longer than 2 days. This must be clarified. The 2-day time period begins at the first loose stool, not from when the product was purchased. Thus, if the first loose stool was at 8 am on Monday morning, the product should not be used after 8 am on Wednesday, 48 hours later. If you decide to continue to self-treat beyond that time, you may experience dehydration and other problems. 

What Age Groups Can Safely Treat Diarrhea?

At one time, diarrhea products were sold for children down to the age of 3 years. That age was too low for safety reasons, so the acceptable age was raised to 6 years. Only products containing loperamide (e.g., Imodium A-D) are safe down to the age of 6 years. Products containing bismuth subsalicylate (e.g., Pepto-Bismol) should not be used without physician approval in those under the age of 12 years, as they may be unsafe. 

Who Should Not Use Nonprescription Products?

Nonprescription products should not be used if you or the child has a fever. Bismuth products do not provide a specific fever grade on the label, so any fever is unacceptable. However, loperamide products specifically state “over 101°F.” Labels for both products suggest consulting a physician before use if the patient has mucus in the stool. Loperamide products state that the patient should consult a physician before use if there is blood in the stool, while bismuth products simply state not to use them with bloody or black stools. Loperamide products suggest speaking to a physician first if you have abdominal pain, bloating, and constipation along with the diarrhea. Bismuth products caution against use if you have an ulcer or bleeding problem, if you are allergic to salicylates (including aspirin), or if you are currently taking other salicylate products (e.g., aspirin, magnesium salicylate, topical methyl salicylate). Bismuth products also suggest speaking to a physician or pharmacist before use if you are taking medications for anticoagulation (blood thinning), diabetes, gout, or arthritis. 

Oral Electrolyte Products

You will notice products in the pharmacy that contain fluids and electrolytes (e.g., Pedialyte). They will help prevent dehydration and fight against electrolyte losses. However, they do not stop diarrhea, and using them does not allow you to go beyond the 48-hour time limit nor does it allow you to ignore the other warnings on the labels of nonprescription antidiarrheals. 


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