Diphenoxylate and atropine (Lomotil®)

Author: OncoLink Team
Last Reviewed: July 22, 2022

Pronounce: dye-fen-OKS-i-late & A-troe-peen

Classification: Antidiarrheal

About: Diphenoxylate and atropine (Lomotil®)

Diphenoxylate and atropine is a medication (made up of two drugs) used to treat diarrhea (loose stool). It is often used as an adjunctive treatment, meaning it is used along with other medications to control diarrhea. This medication works by slowing the movement of the bowel and by preventing spasms in the muscles of the gut. If your cancer treatment is causing diarrhea, your provider may prescribe diphenoxylate and atropine to help manage it.

How this Medication Comes

Diphenoxylate and atropine comes in tablet form and as a liquid solution to be taken orally (by mouth).

How to take Diphenoxylate and Atropine

The dose and how often you take diphenoxylate and atropine depends on your treatment and how severe your diarrhea is. Ask your care team what your dose will be and how often you should take the medication.

It is important to make sure you are taking the correct amount of medication every time. Before every dose, check that what you are taking matches what you have been prescribed. One part of this medication, diphenoxylate, is chemically similar to a narcotic medication (meperidine). The amount of diphenoxylate in this medication is so low that it does not have the same effects as a narcotic and does not produce addiction. However, if overdosage happens or if diphenoxylate and atropine is misused, the effects could be similar to an overdose of a narcotic/opioid. Symptoms of an overdose of diphenoxylate and atropine include difficult or shallow breathing, coma, and lethargy. DO NOT share this medication or give it to someone else, as severe breathing problems and death can occur. This medication should not be given to children less than 6 years of age as cases of severe respiratory depression and coma can occur.

You should not drink alcohol while taking diphenoxylate and atropine. You should not drive a car or operate heavy machinery until you know how this medication affects you.

You should not take this medication if you have a fever or if your stool has mucous or blood in it, or if your stool is black without first talking with your provider. You may need to have your stool tested for certain infections prior to taking this medication, so you should tell your provider that you are having diarrhea prior to taking this medication.

Be sure to tell your healthcare provider about all medications and supplements you take. This medication can interact with other medications and supplements, including barbiturates, benzodiazepines, opioids, buspirone, antihistamines, muscle relaxants, benztropine, glycopyrrolate, hyoscyamine, and monoamine oxidase inhibitors (MAOIs).

Tell your provider if you have ever had problems with your bowels, including diarrhea associated with pseudomembranous enterocolitis (caused by Clostridium difficile) or other enterotoxin-producing bacteria, or if you have ulcerative colitis. Tell your provider if you have or ever had problems with your kidneys or liver.

Storage and Handling

Store this medication in the original container. For tablets, store them at room temperature (below 77°F [25°C]). For liquid solution, store in the original bottle at room temperature. Always use the provided oral syringe for the oral solution. Discard any medication left in an open bottle after 90 days. Keep this medication out of reach of children and pets. Dispose of any unused medication safely.

Where do I get this medication?

This medication  is available through retail/mail order pharmacies.  Your oncology team will work with your prescription drug plan to identify an in-network retail/mail order pharmacy for medication distribution.  You can work with your provider’s office if this medication needs prior authorization.

Insurance Information

Diphenoxylate and atropine may be covered under your prescription drug plan. Patient assistance may be available to qualifying individuals without prescription drug coverage.  Co-pay cards, which reduce the patient co-pay responsibility for eligible commercially (non-government sponsored) insured patients, may also be available. Your care team can help you find these resources if they are available. 

Possible Side Effects of Diphenoxylate and Atropine

This medication is given to manage and/or prevent side effects of your cancer treatment. If you are having side effects from this medication, you should talk to your team about if this medication is necessary to your treatment or if there are other options to help manage the side effect this medication is treating. These are some of the most common side effects:

Central Nervous System (CNS) Effects

Diphenoxylate and atropine may cause drowsiness, fatigue, sedation, dizziness, and weakness. If these effects make it hard to carry out daily life, talk with your provider.

Constipation and Abdominal Cramps

Due to the way this medication works, it may lead to constipation and abdominal (belly) cramps. If you are having any of these side effects after taking diphenoxylate and atropine, stop taking the medication, and notify your provider to discuss the next steps.

Less common, but important side effects can include:

  • Dehydration and Electrolyte Changes: This medication can affect the normal levels of fluid and electrolytes (potassium, magnesium, calcium, etc.) in your body. Your levels will be monitored using blood tests. If your levels become too low, your care team may prescribe fluid or specific electrolytes to be given by IV or taken by mouth. Do not take any supplements without first consulting with your care team.
  • Toxic Megacolon in Patients with Acute Ulcerative Colitis: If you have ulcerative colitis (UC), talk with your provider about the risks and benefits of using diphenoxylate hydrochloride and atropine sulfate, as there is an increased risk of this serious condition. Symptoms of toxic megacolon include pain, bloating, or tenderness of the abdomen (belly), fever, fast heart rate (tachycardia), bloody diarrhea, and painful bowel movements.
  • Atropinism:If overdosage or abuse of this medication happens, a serious condition called “atropinism” can happen. Because this medication has a subtherapeutic (very small) amount of atropine in it, there is a chance that it could cause symptoms associated with high doses of atropine if not taken as prescribed. These include hyperthermia (body temperature becomes too high), tachycardia (fast heart rate), urinary retention (unable to pee), flushing, and dryness of the skin and mucous membranes.

Reproductive Concerns

You should consult with your provider before becoming pregnant or fathering a child while on this medication. You should consult with your healthcare team before breastfeeding while receiving this medication.