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

Prescribing, Dosing, And Potential Side Effects Of This AntiDiarrheal 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

What Is Lomotil?

Lomotil is a mixture of two drugs: atropine and diphenoxylate. Together, these two drugs are used to create an antidiarrheal medication. Lomotil prevents 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.

Is It 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, it is only a small amount. 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 Is Lomotil 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 Is It Prescribed?

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

What Do I Do If I Miss a Dose?

If you miss a dose, take it as soon as you remember. If your next dose should be taken soon, just take that dose. Don't double up, or take more than one dose at a time.

Who Should Not Take Lomotil?

Tell your doctor if you have ever had any of the following conditions:

  • 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

What Are the Side Effects?

Serious side effects of Lomotil can include dizziness or drowsiness. Most side effects are not common when taking this medication, but can can include blurred vision, dryness of skin and mouth, headache, and fever. See the Lomotil side effects page for a complete list

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 (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).

Is Lomotil Safe 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 not 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 Can Lomotil 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.

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