What is Lomotil? Understanding this Prescription Diarrhea Medication

October 11, 2025 •

3 min read

Lomotil, a prescription medication containing the active ingredients diphenoxylate and atropine, is an effective treatment for diarrhea in adults and adolescents over 13 years old. The drug, which is a Schedule V controlled substance, works by slowing down the movement of the gut to reduce the frequency of bowel movements. It is crucial to understand how this combination drug works and its specific safety considerations, especially in comparison to over-the-counter options.

Quick Summary

A prescription medication for severe diarrhea containing diphenoxylate (an opioid) and atropine (an anticholinergic) to slow bowel movements. Its status as a controlled substance requires careful use and adherence to a doctor's instructions. Not for use in young children or certain infectious diarrheas.

Key Points

Prescription Only: Lomotil is a Schedule V controlled substance requiring a valid prescription due to its opioid-like component, diphenoxylate.
Dual Action: It works by combining diphenoxylate to slow down gut motility and atropine to discourage misuse by causing unpleasant side effects in high amounts.
Not for Infectious Diarrhea: Lomotil should not be used for diarrhea caused by bacteria like C. difficile, as it can worsen the infection and lead to severe complications.
Age Restrictions: Lomotil is contraindicated in children under 6 years old due to the risk of severe respiratory depression.
Serious Side Effects: Potential serious side effects include toxic megacolon in ulcerative colitis patients and potential for dependence or overdose with misuse.
Risk of Interactions: Use caution with alcohol and other CNS depressants, as Lomotil can increase drowsiness and sedation.

How Lomotil Works

Lomotil is a combination medication containing diphenoxylate and atropine, working together to treat severe diarrhea.

Diphenoxylate

Diphenoxylate, a synthetic opioid analogue, acts on opioid receptors in the intestines to slow down gut contractions. This process increases the time food and waste spend in the intestines, improving water and electrolyte absorption and reducing the frequency and fluidity of bowel movements. While related to opioids, it primarily affects the gut at therapeutic levels.

Atropine

Atropine is included as an anticholinergic agent to deter misuse. At low levels in Lomotil, its main function is to cause unpleasant side effects like nausea or dry mouth if higher-than-prescribed amounts are taken, making recreational use less appealing, especially since diphenoxylate has potential for abuse.

Indications and Usage

Lomotil is prescribed for the adjunctive management of diarrhea in patients 13 years and older, particularly for severe or chronic cases where other treatments haven't worked. It is not typically the first choice for mild diarrhea. Proper fluid and electrolyte management should always accompany Lomotil treatment, as dehydration must be corrected beforehand.

Important Safety Considerations and Precautions

Using Lomotil requires adherence to important safety warnings and precautions:

Pediatric Risk: Avoid in children under 6 due to risk of severe respiratory issues. For children 6 to 12, a liquid form may be used under strict medical guidance.
Infectious Diarrhea: Contraindicated in diarrhea caused by bacteria like Clostridioides difficile, as it can worsen the infection and lead to complications.
Ulcerative Colitis: Can cause toxic megacolon, a dangerous enlargement of the large intestine, in patients with acute ulcerative colitis.
Other Conditions: Use cautiously in patients with advanced liver or kidney disease due to increased risk of hepatic coma. Those with Down syndrome may be more sensitive to atropine.

Potential Drug Interactions

Avoid certain substances and medications while taking Lomotil due to interaction risks:

Alcohol: Increases the risk of drowsiness and CNS depression.
CNS Depressants: Taking with other sedatives, opioids, or muscle relaxants can enhance sedative effects.
MAO Inhibitors: Can lead to dangerously high blood pressure.

Lomotil vs. Imodium: A Comparison

Lomotil and Imodium (loperamide) both treat diarrhea but differ in availability, mechanism, and risks.


Feature	Lomotil (diphenoxylate/atropine)	Imodium (loperamide)
Availability	Prescription only	Over-the-counter (OTC)
Controlled Status	Schedule V controlled substance	Not a controlled substance
Active Ingredients	Diphenoxylate (opioid) and Atropine (anticholinergic)	Loperamide (opioid-like agent)
Mechanism	Acts on intestinal opioid receptors to slow motility; atropine deters misuse	Binds to intestinal opioid receptors to slow motility and reduce fluid loss
CNS Effects	Potential for more pronounced CNS side effects like drowsiness and confusion	Minimal CNS effects at standard therapeutic levels
Abuse Potential	Possible, especially at high levels	Much lower, but misuse of high levels poses risks
Serious Side Effect Risk	Toxic megacolon, respiratory depression in young children	Heart rhythm problems and potential sudden death with overuse

Potential Side Effects

Common side effects include dizziness, drowsiness, headache, nausea, and stomach pain. Serious side effects like severe allergic reactions, euphoria, depression, or hallucinations can occur. Seek immediate medical help for severe reactions or other serious adverse events.

Administration

Lomotil is typically administered several times daily until diarrhea is controlled. The frequency may be reduced for ongoing management. If no improvement is observed after a certain period of time at the maximum recommended amount, the medication should be discontinued.

Conclusion

Lomotil is a powerful prescription medication for severe diarrhea in adults and adolescents over 13. Its combination of diphenoxylate to slow gut motility and atropine to prevent misuse makes it an effective option. As a controlled substance, it requires careful use under medical supervision. Awareness of side effects, drug interactions, and contraindications, particularly regarding infectious diarrhea and young children, is essential. For milder diarrhea, over-the-counter options may be more suitable. Always consult a healthcare provider with concerns to determine the best treatment. More information can be found in the official FDA drug label by Pfizer.

Frequently Asked Questions

Lomotil is a prescription medication used as an adjunctive therapy for the management of severe or persistent diarrhea in patients aged 13 and older, typically when other, less potent treatments have not been effective.

Most patients can expect to see an improvement in their diarrhea symptoms within 48 hours of starting Lomotil treatment. If there is no clinical improvement for chronic diarrhea after 10 days, treatment should be discontinued.

No, Lomotil is generally not recommended for diarrhea caused by viral or bacterial infections, like the stomach flu or food poisoning. By slowing the gut, it can trap the infection in the intestines and potentially worsen the condition.

When taken at the recommended therapeutic amounts, Lomotil is not typically addictive. However, because it contains an opioid-like substance, diphenoxylate, there is a risk of dependence and misuse, particularly if taken in high amounts or for a prolonged period.

You should avoid consuming alcohol and taking other central nervous system depressants, such as certain antihistamines, opioids, or muscle relaxants, as this can increase the risk of dizziness, drowsiness, and slowed breathing.

Lomotil is a prescription-only, Schedule V controlled substance used for severe or chronic diarrhea, while Imodium (loperamide) is available over-the-counter for milder, acute diarrhea. Lomotil contains two active ingredients (diphenoxylate and atropine), while Imodium contains one (loperamide).

Lomotil is contraindicated in several groups, including children under 6 years old, patients with infectious diarrhea (e.g., C. difficile), those with obstructive jaundice, and individuals with a known hypersensitivity to its components.