Gastroenterology: Medications

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All About Lomotil

Many patients are not as well-informed about prescription medications as they ought to be. We believe that the more you know about your medications, the better. This leaflet is our attempt to inform you about Lomotil and to emphasize the importance of taking it properly. If any of this information causes you concern or if you desire additional information about Lomotil and its use, check with your doctor or pharmacist.

Lomotil overdosage is especially dangerous in young children. Remember to keep this medication, along with all prescription drugs, beyond the sight and reach of children when not in use. Store Lomotil in its original labeled container; the place of storage should be cool, dry, and dark. Carefully read the instructions on the label before each use.

What is Lomotil?

Introduced in 1960, Lomotil is the most commonly known brand of a potent anti-diarrheal drug called diphenoxylate (dye-fen-OX-i-late). Other brands include Lonox, Low-Quel, Logen, Colonil, Diphenatol, and Lo-Trol. The generic form of diphenoxylate is as safe and effective as the brand-name versions; it is also much less expensive. Each tablet contains 2.5 mg. of diphenoxylate and a trace amount of atropine, a chemical that prevents the use of this medication for illicit drug purposes.

What Lomotil is not.

Lomotil does not act to heal inflammation or fight infection in the bowel; it merely controls symptoms. Although chemically related to narcotics, Lomotil rarely causes dependency or serious side effects when taken as prescribed. It does not cause sexual dysfunction.

How does Lomotil work?

Lomotil delays the passage of waste through the digestive tract by slowing bowel contractions. Such action reduces cramping as well as the frequency and looseness of bowel movements.

Taking Lomotil properly

    1. Take the dose as prescribed. Initially, your doctor determines what dose is best for you on the basis of your age, weight, the severity of your diarrhea, and other medical conditions that you may have. In general, adults require one to four tablets of Lomotil per day. However, individuals with severe diarrhea may require higher doses. Your doctor will give you clear instructions about taking Lomotil and will adjust your dosage as needed. The goal, of course, is to control your diarrhea with the lowest possible dose of Lomotil.

    Although Lomotil is usually prescribed for the short-term treatment of simple acute diarrhea, it is sometimes prescribed for the long-term treatment of chronic diarrheal conditions like irritable bowel syndrome, ulcerative colitis, and Crohn¹s disease. This should only be done with your doctor's supervision.

    2. Lomotil can be taken on an empty stomach as well as with food or milk. If necessary, the tablets may be chewed or crushed. You do not need to follow any food or beverage restrictions while taking this medication. Alcohol, however, may increase the sedative effects of Lomotil. During an attack of diarrhea, remember to drink extra fluids. The beverage Gatorade ® is especially helpful in preventing dehydration at such a time.

    3. It is safe to stop taking Lomotil on your own. In fact, you should discontinue this medication if your symptoms disappear. Taking Lomotil after your diarrhea subsides may lead to severe constipation. Moreover, it is safe to decrease the dosage as your symptoms improve. If you have been taking more than three tablets per day for longer than one month, however, you may need to taper off the medication gradually. Ask your doctor about this.

What are the side effects?

All medicines

These side effects should be reported to your doctor:

  • Skin rash, severe itching
  • Unexplained fever
  • Blurred vision
  • Swelling of stomach, vomiting
The following side effects usually do not require medical attention. They often subside as the body becomes used to the medication or when the dosage is decreased. Should these side effects continue or become bothersome, however, check with your doctor:
  • Constipation
  • Dryness of mouth and throat
  • Drowsiness
Side effects not listed above may occasionally occur. If you experience further symptoms, simply check with your doctor, nurse, or pharmacist.


Lomotil merely acts to control the symptoms of diarrhea; it does not cure serious disorders or infections of the bowel. For this reason, you should report any persistent change in bowel habits or episodes of blood-stained diarrhea to your physician.

Please tell your doctor if you are pregnant or breast-feeding. Inform your doctor if you have glaucoma severe liver disease, urinary difficulties, or prostate problems. Also inform your doctor if you have recently taken antibiotics or if you are currently taking any prescription medications, particularly sedatives or tranquilizers. Patients using antidepressants known as MAO inhibitors (Nardil, Marplan) should not take Lomotil.

As Lomotil can cause drowsiness, avoid driving and operating machinery until you have learned how this drug affects you. Avoid alcohol while taking Lomotil.


Lomotil is a powerful drug that can effectively control diarrhea. As with all medications, however, side effects may occur. You can best limit problems with this medication by taking it exactly as prescribed. If you have any questions or concerns, do not hesitate to discuss them with your doctor.

Text & Images Courtesy of Three Rivers Endoscopy Center
© Dr. Robert Fusco, Three Rivers Endoscopy Center, All Rights Reserved

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