Loperamide have negative effects from rebound constipation. If a suspicion exists of diarrhea associated with organisms that can penetrate the intestinal walls, such as or "Salmonella", loperamide is contraindicated as a primary treatment. Loperamide treatment is not used in symptomatic "C. difficile" infections, as it increases the risk of toxin retention and precipitation of toxic megacolon. Loperamide should be administered with caution to people with liver failure due to reduced first-pass metabolism. Additionally, caution should be used when treating people with advanced HIV, as cases of both viral and bacterial toxic megacolon have been reported. If abdominal distension is noted, therapy
Loperamide with loperamide should be discontinued. The use of loperamide in children under 2 years is not recommended. Rare reports of fatal paralytic ileus associated with abdominal distention have been made. Most of these reports occurred in the setting of acute dysentery, overdose, and with very young children less than 2 years of age. A review of loperamide in children under 12 years old found that serious adverse events occurred only in children under 3 years old. The study reported that the use of loperamide should be contraindicated in children who are under 3, systemically ill, malnourished, moderately dehydrated, or have