Side Effects of Lomotil (Lonox, Vi-Atro)

This Drug Might Be Used To Treat Diarrhea From IBS Or Other Conditions

What Is Lomotil?

Lomotil (diphenoxylate hydrochloride; atropine sulfate) is a drug that slows down or stops diarrhea by slowing the contractions of the large intestine. Lomotil may be prescribed by a healthcare provider for the diarrhea associated with irritable bowel syndrome (IBS) or other digestive diseases or conditions. Lomotil is a controlled substance and is chemically related to a narcotic.

A healthcare provider showing a prescription to a senior person

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Warnings and Precautions When Using Lomotil

Lomotil should not be used to treat antibiotic-associated diarrhea or diarrhea resulting from infectious bacteria, such as Escherichia coli, Salmonella, or Shigella. Diarrhea from these causes should be ruled out before Lomotil is prescribed. The reason is that because when diarrhea is caused by a bacteria, the bacteria needs to leave the body in order for a person to get better. A drug like Lomotil will prevent diarrhea and prolong the time the bacteria spends in the body.

Lomotil should also only be used under the supervision of a healthcare provider by anyone who has liver disease or ulcerative colitis (due to a risk of a rare but serious condition called toxic megacolon).

Taking Lomotil can increase the effects of barbiturates, tranquilizers, or alcohol, and can cause side effects such as sedation. Tell your healthcare provider if you are taking any other drugs while taking Lomotil, and you shouldn't drink alcohol while taking it. It should also not be taken at doses higher than what is prescribed because of the risk of addiction to diphenoxylate hydrochloride. Taking Lomotil as prescribed to treat diarrhea, however, will not result in addiction.

Recommended Dosage of Lomotil

It is very easy to become confused about dosage, especially when using the liquid formulation. That's why it is important to only use the dropper that comes with the medication, especially when giving Lomotil to children.

Adults: A typical dose is two 2.5 mg tablets four times a day (for 20 mg a day) or 5 to 10 ml four times a day of the liquid formulation. When diarrhea slows down, which generally happens in about 48 hours, less Lomotil can be taken.

Children: Don't give Lomotil to children under the age of 2. For older children, use the liquid, and only use this drug under the supervision of a medical professional. The dosage will vary by weight, so it's important that the child's weight is known and that a healthcare provider prescribes the correct amount. A dosing schedule is available in the Lomotil Prescribing Information, which is provided for reference only. Children with Down syndrome may be more prone to experience side effects as a result of the atropine component of Lomotil.

Possible Side Effects of Lomotil

Check with your healthcare provider if any of the following side effects continue or are bothersome:

  • Blurred vision
  • Confusion
  • Difficult urination
  • Dizziness or lightheadedness
  • Drowsiness
  • Dryness of skin and mouth
  • Fever
  • Headache
  • Depression
  • Numbness of hands or feet
  • Skin rash or itching
  • Swelling of the gums

Always Notify Healthcare Provider

Call your healthcare provider if any of the following side effects are severe and occur suddenly, since they may be signs of a more severe and dangerous problem with your bowels.

  • Bloating
  • Constipation
  • Loss of appetite
  • Severe stomach pain with nausea and vomiting

Symptoms of an Overdose of Lomotil

  • Blurred vision (continuing) or changes in near vision
  • Drowsiness (severe)
  • Dryness of mouth, nose, and throat (severe)
  • Fast heartbeat
  • Shortness of breath or troubled breathing (severe)
  • Unusual excitement, nervousness, restlessness, or irritability
  • Unusual warmth, dryness, and flushing of the skin

Other side effects not listed above may also occur in some patients. If there are any other effects, check with a healthcare provider. This information is meant only as a guideline. Always consult a practitioner or pharmacist for complete information about prescription medications.

1 Source
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  1. Pfizer, Inc. Prescribing Information - Lomotil. Uodated Oct 2005.

By Amber J. Tresca
Amber J. Tresca is a freelance writer and speaker who covers digestive conditions, including IBD. She was diagnosed with ulcerative colitis at age 16.