What You Need To Know About Lomotil (Atropine and Diphenoxylate)

Prescribing, Dosing, And Potential Side Effects Of This Anti-Diarrheal Drug

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Lomotil may be prescribed for diarrhea, such as may occur with irritable bowel syndrome. Image © Lauren Nicole / DigitalVision / Getty Images

Lomotil is a combination of two drugs: atropine and diphenoxylate. Together, these two medications are used as an antidiarrheal. Lomotil works by preventing spasms in the muscles of the gut and the bladder by causing them to relax. This drug also treats diarrhea by slowing the function of the bowel.

Status as a Controlled Substance

One part of Lomotil, diphenoxylate, is classified as a narcotic. This might seem concerning, but it's important to note that when the drug is used correctly and as prescribed, there is only a small amount of diphenoxylate present. Some people have been known to abuse lomotil but they would be taking the drug in much higher amounts than would be used to treat diarrhea. 

How Lomotil Is Taken

Lomotil comes in the forms of a tablet and an oral liquid. The liquid form should be measured carefully to ensure the correct dosage is being administered. Lomotil should also be taken with a glass of water.

Why Lomotil Is Prescribed

Lomotil may be prescribed for diarrhea caused by irritable bowel syndrome (IBS) or for other conditions as needed.

What To Do About a Missed Dose

If a dose is missed, take it as soon as it is remembered. If the next dose should be taken soon, just take that dose. Don't double up, or take more than one dose at a time.

Precautions in Taking Lomotil

Tell a doctor if any of the following conditions are currently present or have been diagnosed in the past:

  • Asthma, chronic lung disease, or allergies
  • Difficulty urinating
  • Down's syndrome
  • Glaucoma
  • Heart disease
  • Hiatal hernia or reflux disease
  • Hypertension (high blood pressure)
  • Kidney disease
  • Liver disease
  • Myasthenia gravis
  • Numbness or tingling in hands or feet
  • Prostate enlargement - BPH
  • Severe ulcerative colitis when bowel movements have stopped
  • Thyroid problems

Side Effects

Serious side effects of Lomotil can include dizziness or drowsiness. Most side effects are not common when taking this medication, but they can include blurred vision, dryness of skin and mouth, headache, and fever.

Medication Interactions

Lomotil could interact with several different types of medications, including some that are available over-the-counter. Some of the medications currently known to interact with Lomotil include:

  • Antidepressants (Haldol, Elavil)
  • Antihistamines (Benadryl)
  • Anxiety medicines
  • Monoamine oxidase (MAO) inhibitors (Nardil, Parnate)
  • Muscle relaxants
  • Pain relievers
  • Sedatives (Ambien, Dalmane, Restoril)

Food Interactions

Lomotil is not known to interact with any foods. People taking Lomotil should avoid alcoholic drinks, however, as the two together could have an increased sedative effect (and cause excessive drowsiness). When taking Lomotil, take care to avoid alcohol from unexpected sources, such as over-the-counter cough suppressants or cold products (Nyquil, for example).

Safety During Pregnancy

The FDA has classified Lomotil as a type C drug, which means that the effect that Lomotil has on an unborn child is unknown. There are no data from controlled studies of the effects of Lomotil on pregnant women. There have been some studies done that have shown a concern of congenital defects in connection with atropine.

Lomotil should only be used during pregnancy if clearly needed. Notify the prescribing doctor if you become pregnant while taking Lomotil.

It is not known if Lomotil passes into breast milk, but it is theorized that atropine does pass into breast milk. It's unknown if diphenoxylate passes into breast milk.

How Long Lomotil Can Be Taken Safely

Under the supervision of a physician, Lomotil can be used long-term. Dependency to Lomotil is a concern if the drug is taken at very high doses which would not be prescribed for the treatment of diarrhea. For this reason, it is very important to follow the dosing schedule carefully and not take more Lomotil than prescribed.

A Word From Verywell

Lomotil is largely considered to be safe and effective when taken in the appropriate doses. There is the potential for it to be abused and/or become habit-forming, but this is not a concern when it is taken as prescribed by a doctor. It's important to understand why diarrhea is occurring, especially when considering the long-term use of anti-diarrheal medications. For those who have had surgery on their intestines or who have certain conditions, long-term use might be needed.

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