Twenty-five men with induced shigellosis received a mixture of diphenyoxylate hydrochloride with atropine (Lomotil), placebo and oxolinic acid (Oxabid), or a second placebo in four randomly assigned treatment groups. Diarrhea was decreased by oxolinic acid or Lomotil therapy, while fever was prolonged in the group receiving only Lomotil. Two men who received Lomotil alone had fever until the drug regimen was discontinued five days later. Shigellae were eradicated from stool in four of six men treated with oxolinic acid alone, but in only one of six men receiving oxolinic acid and Lomotil.
Lomotil may be contraindicated in shigellosis. Diarrhea may represent a defense mechanism when disease is caused by a bacterial pathogen that must penetrate the intestinal epithelium to produce illness where increased intestinal motility (diarrhea) may decrease contact time between the invasive bacteria and mucosal cells.
DuPont HL, Hornick RB. Adverse Effect of Lomotil Therapy in Shigellosis. JAMA. 1973;226(13):1525–1528. doi:10.1001/jama.1973.03230130013006