Updated May 30, 2026, 4:23 PM
AntidiarrhealUS FDA Database Verified

diphenoxylate with atropine (Rx)

Generic: Diphenoxylate with atropine

Brand: Lomotil, Lonox

(dye-fen-ox'i-late)

Pregnancy Category: C
Controlled substance schedule V (diphenoxylate/atropine); IV (difenoxin/atropine (US))
Do not confuse: Lomotil/Lamictal/Lamasil/Lanoxin/Lasix/Ludomil

Pharmacological Action

Inhibits gastric motility by acting on mucosal receptors responsible for peristalsis

Therapeutic outcome: Decreased loose stools

Uses

Acute nonspecific and acute exacerbations of chronic functional diarrhea

Contraindications

Hypersensitivity, pseudomembranous colitis, child <2 yr, severe electrolyte imbalances, diarrhea associated with organisms that penetrate intestinal mucosa

Precautions: Pregnancy C, breastfeeding, hepatic disease, ulcerative colitis, severe hepatic disease, substance abuse, dehydration

Dosage & Routes

diphenoxylate/atropine

Adult: PO 5 mg qid, titrated to patient response, max 8 tabs/24 hr Child 2-12 yr: PO (liquid only) 0.3-0.4 mg/kg/day in 4 divided doses difenoxin/atropine

Adult: PO initially 2 tabs, then 1 tab after each loose stool or q3-4 hr prn, max 8 tabs/day

Available forms: diphenoxylate/atropine: tab 2.5 mg diphenoxylate/0.025 mg atropine; liq 2.5 mg diphenoxylate/0.025 mg atropine/5 ml; difenoxin/atropine: tabs 1 mg difenoxin/0.025 atropine

Implementation • Give for 48 hr only; tabs may be given with food, crushed and mixed with fluids; liquid should be measured accurately

Adverse Effects

CNS: Dizziness, drowsiness, light-headedness, headache, fatigue, nervousness, insomnia, confusion

EENT: Blurred vision, burning eyes

GI: Nausea, vomiting, dry mouth, epigastric distress, constipation, paralytic ileus, toxic megacolon

MISC: Anaphylaxis, angioedema

RESP: Respiratory depression

Pharmacokinetics

Absorption: Well absorbed

Distribution: Unknown

Metabolism: Liver, active metabolite

Excretion: Kidneys

Half-life: 2½ hr

Pharmacodynamics

Onset: 45-60 min

Peak: 2 hr

Duration: 3-4 hr

Interactions

Individual drugs

Alcohol: increased action of alcohol Amantadine, amoxapine, diphenhydrAMINE, clemastine, cloZAPine, cyclobenzaprine, disopyramide, loperamide, maprotiline, olanzapine: decreased GI motility, possible toxic megacolon

Drug classifications

Anticholinergics: increased anticholinergic effect Antimuscarinics, phenothiazines, tricyclics: decreased GI motility, possible toxic megacolon

Barbiturates: increased action of barbiturates CNS depressants: increased action of CNS depressants

MAOIs: hypertensive crisis; do not use together

Opiates: increased action of opioids

Nursing Considerations

Assessment • Monitor electrolytes (potassium, sodium, chloride) if on long-term therapy; fluid status, skin turgor • Assess bowel pattern before, during treatment; check for rebound constipation after termination of medication; check bowel sounds • Check response after 48 hr; if no response, product should be discontinued and other treatment initiated • Assess for abdominal distention and toxic megacolon, which may occur in ulcerative colitis • Assess hepatic function if on long-term therapy

Patient/family education • Advise patient to avoid alcohol and OTC products unless directed by prescriber; may cause increased CNS depression • Caution patient not to exceed recommended dosage; that product may be habit forming • Advise patient that product may cause drowsiness; to avoid hazardous activities until response to product is determined • Teach patient that dry mouth can be decreased by frequent sips of water, hard candy, sugarless gum

Evaluation

Positive therapeutic outcome: Decreased diarrhea

Reference

Mosby's Drug Guide; Davis Drug Guide

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