Lomotil (diphenoxylate hydrochloride/atropine sulfate) is a prescription drug used to treat diarrhea. Lomotil can cause side effects that range from mild to serious. Examples include dizziness, drowsiness, and headache.

Specifically, Lomotil is used to treat diarrhea in adults and children ages 13 years and older.

The active ingredients in Lomotil are diphenoxylate hydrochloride and atropine sulfate. An active ingredient is what makes a drug work. The drug comes as an oral tablet.

Keep reading to learn about the common, mild, and serious side effects Lomotil can cause. For a general overview of the drug, including details about its uses, see this article.

Some people may experience mild to serious side effects during Lomotil treatment. Examples of the drug’s commonly reported side effects include:

Mild side effects have been reported with Lomotil. These include:

In most cases, these side effects should be temporary. And some may be easily managed. But if you have ongoing or bothersome symptoms, talk with your doctor or pharmacist. Do not stop taking Lomotil unless your doctor recommends it.

Lomotil may cause mild side effects other than those listed above. See the drug’s prescribing information for details.

* To learn more about this side effect, see the “Side effects explained” section below.

Serious side effects have been reported with Lomotil. These include:

In children under the age of 6 years, Lomotil can also cause slow or difficult breathing leading to death, and coma leading to brain damage or death. Lomotil is not prescribed for children under the age of 13.

If you develop serious side effects while taking Lomotil, call your doctor right away. If the side effects seem life threatening or you think you’re having a medical emergency, immediately call 911 or your local emergency number.

* To learn more about this side effect, see the “Side effects explained” section below.
† Withdrawal symptoms are side effects caused by suddenly stopping a drug. Dependence is when your body gets used to a drug and needs it for you to function as usual.

Note: After the Food and Drug Administration (FDA) approves a drug, it tracks and reviews side effects of the medication. If you’d like to notify the FDA about a side effect you’ve had with Lomotil, visit MedWatch.

Lomotil is prescribed to treat diarrhea in children ages 13 and older.

According to the drug’s studies, there’s an increased risk of atropine (ingredient of Lomotil) poisoning* in pediatric patients with Down syndrome.

In children under the age of 6 years, Lomotil can cause coma which can result in brain damage or death. And Lomotil can cause slow or difficult breathing which can also lead to death.

Talk with your doctor or pharmacist for more information about the potential side effects of Lomotil in children.

* To learn more about this side effect, see the “Side effects explained” section below.

Get answers to some frequently asked questions about Lomotil’s side effects.

How do the side effects of Lomotil compare with those of Imodium?

Imodium (loperamide) is an over-the-counter medication approved to treat diarrhea. Imodium has fewer side effects than Lomotil when taken according to package instructions. The main side effect of Imodium in studies is constipation.

Lomotil and Imodium may cause dizziness, drowsiness, stomach pain, and allergic reaction. Each medication has a risk of misuse and dependence. With misuse, a person takes a drug in a way or for a reason other than how or why it was prescribed. Dependence is when your body gets used to a drug and needs it for you to function as usual.

Taking more than the recommended dosage for either medication poses risks of extreme drowsiness, hallucinations, and difficulty breathing. Also, the Food and Drug Administration (FDA) warns that high doses of Imodium may cause an irregular heartbeat that can lead to sudden death.

Following dosing instructions for Imodium and Lomotil can greatly reduce the risk of severe side effects.

Does Lomotil cause long-term side effects?

It’s possible. Long-term side effects include those that may start any time you’re taking a drug, even if you’ve taken it for a long time. It also includes side effects that may not go away even after you stop taking the drug.

Examples of long-term side effects reported in Lomotil’s studies include dependence and withdrawal. (Dependence is when your body gets used to a drug and needs it for you to function as usual. Withdrawal symptoms are side effects that can happen when you stop taking a drug your body has become dependent on.)

Lomotil is considered a Schedule V drug by federal law*. This means it carries the risk of dependence and misuse. (With misuse, a person takes a drug in a way or for a reason other than how or why it was prescribed.)

Lomotil’s main ingredient, diphenoxylate hydrochloride, is similar to a pain medication called meperidine. Adults and children ages 13 years and older taking FDA-approved doses of Lomotil for diarrhea have a rare risk of withdrawal and dependence. But long-term use or taking more than the prescribed dose of the drug increases this risk.

Withdrawal and dependence from Lomotil may cause symptoms such as:

  • stomach cramps
  • nausea
  • vomiting
  • feeling you need more of the medication than prescribed for it to work

It’s critical that you take Lomotil exactly as your doctor prescribes to prevent the risk of withdrawal and dependence. Let them know if you have a history of substance misuse. If Lomotil isn’t managing your diarrhea or it stops working, notify your doctor right away.

If you’re concerned about possible long-term side effects from Lomotil, talk with your doctor or pharmacist.

* Lomotil is a controlled substance in the United States. This means the drug has an approved medical use, but may be misused for other purposes. It also means government agencies, doctors, and pharmacists pay close attention to how it’s prescribed and used. Your doctor will assess your risk of misuse and addiction before prescribing this drug for you. (Addiction is when a drug is taken even if it’s causing harmful effects.) People with a mental health condition or who have misused drugs or alcohol in the past may be more likely to have misuse or addiction problems.

Learn more about some of the side effects Lomotil may cause.

Atropine poisoning

Poisoning from atropine (an active ingredient* in Lomotil) was a rare side effect reported in Lomotil studies. Atropine poisoning may cause symptoms such as:

Adults taking Lomotil at FDA-approved doses for diarrhea are at very low risk of atropine poisoning. Children, especially those younger than 6 years or with Down syndrome, have the highest risk. (This drug is not prescribed for children under the age of 13 years.)

What might help

If you or someone you’re caring for develops symptoms of atropine poisoning, seek emergency medical attention right away. Atropine poisoning can be fatal.

* An active ingredient is what makes a drug work.

Intestinal inflammation and infection

Lomotil can slow down the movement in your stomach and intestines. This could cause an increase in harmful bacteria and inflammatory toxins. Studies show people with infection in their intestines had worse problems after taking Lomotil. Problems included harmful bacteria overgrowth, bleeding intestines, and bacteria in the bloodstream.

Symptoms of intestinal inflammation and infection include:

The risk of intestinal inflammation and infection increases when taking Lomotil at the same time as an antibiotic.

What might help

Before taking Lomotil, let your doctor know if you’ve had an intestinal infection recently or are currently taking antibiotics. Notify them immediately if you develop intestinal inflammation and infection symptoms, as these can lead to a life threatening blood infection.

Allergic reaction

Like most drugs, Lomotil can cause an allergic reaction in some people. Symptoms can be mild to serious and can include:

  • skin rash
  • itchiness
  • flushing (temporary warmth, redness, or deepening of skin color)
  • swelling under your skin (usually in your eyelids, lips, hands, or feet)
  • swelling of your mouth, tongue, or throat, which can make it hard to breathe

What might help

If you have mild symptoms of an allergic reaction, such as a mild rash, call your doctor right away. They may suggest a treatment to manage your symptoms. Examples include:

  • an oral antihistamine, such as Benadryl (diphenhydramine)
  • a product you apply to your skin, such as hydrocortisone cream

If your doctor confirms you’ve had a mild allergic reaction to Lomotil, they’ll decide whether you should continue taking it.

If you have symptoms of a severe allergic reaction, such as swelling or trouble breathing, call 911 or your local emergency number right away. These symptoms could be life threatening and require immediate medical care.

If your doctor confirms you’ve had a serious allergic reaction to Lomotil, they may have you switch to a different treatment.

Keeping track of side effects

During your Lomotil treatment, consider taking notes on any side effects you’re having. You can then share this information with your doctor. This is especially helpful when you first start taking a new drug or using a combination of treatments.

Your side effect notes can include things such as:

  • what dose of the drug you were taking when you had the side effect
  • how soon you had the side effect after starting that dose
  • what your symptoms were
  • how your symptoms affected your daily activities
  • what other medications you were taking
  • any other information you feel is important

Keeping notes and sharing them with your doctor will help them learn more about how Lomotil affects you. They can then use this information to adjust your treatment plan if needed.

Below is important information you should consider before taking Lomotil.

Warnings

Lomotil can sometimes cause harmful effects in people with certain conditions. This is known as a drug-condition interaction. Other factors may also affect whether Lomotil is a good treatment option for you.

Talk with your doctor about your health history before starting Lomotil. Be sure to tell them if any of the following factors apply to you:

  • younger than age 13 years
  • dehydration
  • infectious diarrhea
  • active ulcerative colitis
  • obstructive (post-hepatic) jaundice
  • liver or kidney disease
  • taking an antibiotic
  • taking Demerol (meperidine)
  • taking other drugs that cause dizziness or drowsiness, such as:
  • history of substance misuse (taking a drug in a way or for a reason other than how it was prescribed)
  • previous allergic reaction to Lomotil
  • pregnancy
  • breastfeeding

Alcohol and Lomotil

You should not take Lomotil with alcohol. Drinking alcohol while taking Lomotil may make you feel more drowsy and can increase your risk of dizziness, confusion, depression, fatigue (low energy), and hallucinations.

If you have questions about consuming alcohol while taking Lomotil, talk with your doctor or pharmacist.

Pregnancy and breastfeeding with Lomotil

There is limited information about the safety of Lomotil use while pregnant or breastfeeding.

Pregnancy

There aren’t enough studies to know exactly how Lomotil affects pregnant people. The drug is usually prescribed for someone who’s pregnant only if the benefits of treatment outweigh the potential risks to the fetus.

If you’re pregnant or planning a pregnancy, talk with your doctor about the risks and benefits of Lomotil.

Breastfeeding

It’s not known whether Lomotil is safe to take while breastfeeding. Both ingredients, diphenoxylate and atropine, can pass into breast milk and may affect a child who’s breastfed. Children under the age of 6 years are at risk of serious side effects from this medication. (See the “Side effects in children” section for more details.)

If you’re breastfeeding or planning to do so, talk with your doctor before starting this medication.

Like most drugs, Lomotil can cause several side effects ranging from mild to serious. But most are temporary and go away after a few days to weeks. If you have questions about the side effects that Lomotil can cause, talk with your doctor. Examples of questions to help get you started include:

  • Can Lomotil cause confusion?
  • Do I have an increased risk of becoming addicted to Lomotil?
  • Can Lomotil make diarrhea worse?
  • Will Lomotil make me too sleepy to drive?

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Disclaimer: Healthline has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.