Short answer: Lomotil combines diphenoxylate, an opioid-related drug that slows the gut, with a small dose of atropine added to discourage misuse. It treats diarrhea and is a Schedule V controlled substance. It is dangerous for young children, in whom even a few tablets can cause delayed, life-threatening breathing problems.
Key takeaways
- What it is: Diphenoxylate and atropine is an opioid-derived antidiarrheal with atropine and a Schedule V controlled substance in the US.
- Main uses: Diarrhea (adjunct).
- Timing: effects start in 45 to 60 minutes and last 3 to 4 hours.
- Most dangerous mix: MAO inhibitors, which can cause possible hypertensive crisis.
- Naloxone: it reverses an overdose.
- Dependence risk: Low at prescribed doses.
- Legal route: only with a prescription from a DEA-registered clinician, filled by a licensed pharmacy.
What is diphenoxylate and atropine?
Diphenoxylate slows the muscle contractions of the gut and is used, alongside fluids and treating the cause, for diarrhea in adults and children 13 and older.
The tiny dose of atropine has no effect at normal doses but causes unpleasant effects, such as dry mouth, flushing, and a fast heartbeat, at high doses, which discourages misuse.
Quick facts
| Fact | Diphenoxylate and atropine |
|---|---|
| Generic name | Diphenoxylate hydrochloride and atropine sulfate |
| Brand names | Lomotil, Lonox |
| Drug class | Opioid-related antidiarrheal (diphenoxylate) with an anticholinergic (atropine) |
| US legal status | Schedule V, prescription only |
| Approved uses | Additional treatment of diarrhea in people 13 and older |
| Forms | Tablets (2.5 mg diphenoxylate, 0.025 mg atropine); liquid |
| Onset | 45 to 60 minutes |
| Half-life | About 2.5 hours; difenoxin 12 to 14 hours |
| Reversal agent | Naloxone (repeated or prolonged dosing may be needed) |
How long does diphenoxylate and atropine last?
- Starts working: 45 to 60 minutes
- Effects last: 3 to 4 hours
- Half-life: About 2.5 hours; difenoxin 12 to 14 hours
If diarrhea does not improve within 10 days at the maximum dose, it is unlikely to help; see a clinician.
Timing varies with the dose, the form, how it is taken, liver and kidney function, age, and other drugs taken at the same time.
What are the biggest risks of diphenoxylate and atropine?
Common side effects include dizziness, drowsiness, dry mouth, nausea, and constipation.
Children: accidental ingestion of even one or two tablets by a young child can cause breathing problems that appear up to 30 hours later. Keep it locked away.
Infections and colitis: slowing the gut in diarrhea caused by toxin-producing bacteria, such as C. difficile, or in ulcerative colitis can lead to toxic megacolon. It should not be used for these conditions.
What should you never mix with diphenoxylate and atropine?
| Combined with | What happens | Label guidance |
|---|---|---|
| MAO inhibitors | Possible hypertensive crisis | Avoid |
| Alcohol, benzodiazepines, sleep medicines, opioids | Additive sedation and slowed breathing | Use caution |
| Other anticholinergics (antihistamines, tricyclics, bladder medicines) | Dry mouth, urinary retention, confusion, overheating | Use caution |
Check any combination with the DoseUses combination checker or ask a pharmacist.
What are the signs of a diphenoxylate and atropine overdose, and what should you do?
Overdose causes atropine effects first, flushing, dry skin and mouth, high temperature, and a fast heartbeat, followed by sleepiness, pinpoint pupils, and slowed breathing that can be delayed and prolonged.
If someone may have overdosed
- Call 911 if the person is unresponsive, cannot be woken, has blue or gray lips, or is breathing slowly or not at all.
- Give naloxone (Narcan or a generic nasal spray, sold without a prescription) into one nostril. If there is no response after 2 to 3 minutes, give another dose.
- If you are trained, give rescue breaths. Otherwise place the person on their side so they do not choke.
- Stay with them. Naloxone can wear off before diphenoxylate and atropine does, so the overdose can return even after the person wakes up.
- Most states have Good Samaritan laws that protect people who call 911 for an overdose from some drug charges.
What is diphenoxylate and atropine withdrawal like, and how long does it last?
Physical dependence is rare at recommended doses for short periods. Long-term, high-dose use can cause opioid-like dependence.
- 12 to 24 hoursEarly symptomsRestlessness, sweating, runny nose, and stomach cramps after long-term high-dose use.
- Days 1 to 3PeakDiarrhea, nausea, aches, and poor sleep.
- Within 1 weekResolvesSymptoms usually fade over several days.
See the withdrawal timelines and the full diphenoxylate and atropine withdrawal guide.
Is diphenoxylate and atropine legal?
In the United States, diphenoxylate and atropine is a Schedule V controlled substance. The only legal way to get it is with a prescription from a clinician registered with the Drug Enforcement Administration (DEA), filled by a licensed pharmacy. Depending on state law, that can be a physician, nurse practitioner, or physician assistant.
- Refills: Schedule V prescriptions can be refilled as the prescriber authorizes, subject to state law.
- Telehealth: federal flexibilities let DEA-registered clinicians prescribe Schedule II to V medicines after a telemedicine visit, without a prior in-person exam, through December 31, 2026. A permanent DEA rule was under final review in late 2026. State rules can be stricter.
- Monitoring: prescribers and pharmacists in most states check a prescription drug monitoring program, a database of controlled-substance prescriptions, before prescribing or dispensing.
Outside the United States
| Country | Status |
|---|---|
| United Kingdom | Prescription-only medicine (co-phenotrope) |
| International | Diphenoxylate is in Schedule I of the 1961 Single Convention; low-dose preparations with atropine are exempted in Schedule III |
Frequently asked questions about diphenoxylate and atropine
Is Lomotil a narcotic?
Diphenoxylate is chemically related to meperidine and is a Schedule V controlled substance, the lowest federal schedule.
Why does Lomotil contain atropine?
To discourage misuse. Large doses cause unpleasant effects such as dry mouth, flushing, and a racing heart.
Can children take Lomotil?
No. It is contraindicated under age 6 and not recommended under 13, because it can cause severe, delayed breathing problems.
Is Lomotil stronger than Imodium?
Both slow the gut. Loperamide (Imodium) is available without a prescription and is usually tried first.
How long can I take Lomotil?
If diarrhea does not improve within 10 days at the maximum dose, it is unlikely to help; see a clinician.
Sources
- Lomotil (diphenoxylate and atropine) prescription information, DailyMed, US National Library of Medicine.
- Controlled Substance Schedules, DEA Diversion Control Division.
- Prescribing controlled substances via telehealth, US Department of Health and Human Services.
- BeSafeRx: Your Source for Online Pharmacy Information, US Food and Drug Administration.
- Safe Pharmacy, National Association of Boards of Pharmacy.
- One Pill Can Kill, US Drug Enforcement Administration.
- International drug control conventions, United Nations Office on Drugs and Crime.
This guide summarizes the sourced DoseUses Diphenoxylate and atropine profile, written from FDA labels, DEA rules, and federal health agencies. It is educational and is not medical advice. Last updated October 5, 2026.
