Lomotil (co-phenotrope)

What is Lomotil used for?

  • Relieving acute diarrhoea.
  • Relieving diarrhoea and pain associated with mild or long-term ulcerative colitis.
  • Regulating stool formation in people who have had a olostomy to reduce the number of stools produced and make them less watery.

Pharmacist - M.B.A. (Public Health) D.I.C.

Lomotil (co-phenotrope)

How does Lomotil work? When you have diarrhoea…

Garvan J. Lynch
MBA (Public Health)

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How does Lomotil work?

  • When you have diarrhoea, your body loses water and important salts. As well as giving you Lomotil, the doctor may give you medicine to help replace the water and salts that you have lost. In some cases the doctor will not give you Lomotil until after the water and salts have been replaced.
  • Lomotil tablets contain two ingredients, diphenoxylate hydrochloride and atropine sulfate. This combination of medicines is known as co-phenotrope.
  • Co-phenotrope works by slowing down the muscular contractions of the intestine. It reduces the speed at which the gut contents are pushed through the intestines, allowing more time for water and electrolytes to be reabsorbed from the gut contents back into the body. The diphenoxylate in Lomotil helps stop diarrhoea by slowing down the movement of the muscles in your intestines. This results in firmer stools that are passed less frequently and so controls diarrhoea.
  • Atropine relieves the sharp pains you sometimes get with diarrhoea. Slowing down the muscles in the intestines also relieves painful spasms.

How do I take Lomotil?

Always follow the instructions given by your doctor or pharmacist and do not take more than the recommended dose. The usual doses are as follows:

  • Adults and teenagers aged 16 years and over should take four tablets initially, followed by two tablets after six hours and then a further two tablets every six hours.
  • Children aged 13 to 16 years should take two tablets three times a day.
  • Children aged 9 to 12 years should take one tablet four times a day.
  • Children aged 4 to 8 years should take one tablet three times a day.


Most people only need to take Lomotil for a few days to control diarrhoea. If you're taking it because you have a colostomy or ileostomy you may need to take it on a more long-term basis. Always follow the instructions given by your doctor or pharmacist.

Lomotil tablets should be swallowed with a drink of water. They can be taken either with or without food.

If you forget to take a dose, just leave out that dose and wait to take your next dose as usual when it's due. Do not take a double dose to make up for a missed dose.

What should I know before taking Lomotil?

  • Don't take this medicine and consult a doctor instead if any of the following apply to you: you have diarrhoea that started either during or after taking a course of antibiotics, if the diarrhoea contains yellow or greenish mucus or blood, or if you also have a fever.
  • Acute diarrhoea makes you lose more fluids and salt than you usually would and can make you dehydrated. This medicine only treats the symptoms of diarrhoea and so will not rehydrate you. You should make sure that you drink plenty of fluids, and you may also want to take an oral rehydration therapy, which is a soluble powder containing sugars and salts, to help rehydrate you. This is particularly important for frail and elderly people. Rehydration salts can be bought from pharmacies or may be prescribed by your doctor.
  • If you get any swelling of your stomach or constipation after taking Lomotil, don't take any further doses and consult your doctor.
  • Lomotil may make you feel sleepy or dizzy. If affected do not drive or operate machinery. Avoid drinking alcohol as it may make these problems worse.

Who shouldn't take Lomotil?

  • Children under four years of age. Co-phenotrope should not be given to children under 16 years of age unless prescribed by a doctor.
  • People with severe constipation, or a lack of movement or blockage in the gut.
  • People with pyloric stenosis, a condition where the opening from the stomach into the small intestine is narrowed.
  • People with severe acute ulcerative colitis.
  • People with diarrhoea caused by inflammation of the gut following antibiotic treatment (antibiotic-associated pseudomembranous colitis).
  • People with a head injury or raised pressure inside the skull.
  • People with jaundice.

Can I take Lomotil while pregnant or breastfeeding?

Only if it is prescribed by your doctor. If you're pregnant or breastfeeding you should get advice from your doctor before taking this medicine. Since its safety for use during pregnancy and breastfeeding has not been fully established, it should only be used with caution, and only if the expected benefit to the mother outweighs any potential risk to the baby. Co-phenotrope may pass into breast milk. You are breastfeeding, you should use an alternative form of infant feeding while you are taking LOMOTIL.

What are the possible side effects of Lomotil?

  • Nausea and vomiting
  • Abdominal pain
  • Constipation
  • Loss of appetite.
  • Feeling tired or sleepy
  • Dizziness
  • Feeling generally unwell
  • Confusion
  • Restlessness
  • Headache
  • Difficulty passing urine
  • Dry mouth or skin
  • Fever or flushing
  • Changes in heart rate
  • A condition called paralytic ileus, where the bowels become paralysed and stop working
  • Hallucinations
  • Changes in mood
  • Raised pressure in the eyeball
  • Dilated pupils and blurred vision

Can I take Lomotil with other medicines?

It's important to tell your doctor or pharmacist if you're already taking any medicines, including those bought without a prescription and herbal medicines, before starting treatment with Lomotil. Similarly, check with your doctor or pharmacist before taking any new medicines with this one, to make sure that the combination is safe.

These are the main things to be aware of:

If you feel sleepy while taking Lomotil this may be made worse if you take any of the following medicines as well:

  • antihistamines that cause drowsiness
  • baclofen
  • benzodiazepines
  • sleeping tablets
  • strong opioid painkillers
  • tricyclic antidepressants

You're more likely to get side effects such as constipation, dry mouth, blurred vision or difficulty passing urine, if you take Lomotil with other medicines that can have antimuscarinic effects

Lomotil may oppose the effect of the following medicines:

  • domperidone
  • galantamine
  • metoclopramide
  • neostigmine
  • pilocarpine
  • pyridostigmine

Lomotil may decrease the blood level of the Parkinson's medicine levodopa, which could make it less effective.

If you get a dry mouth while taking Lomotil you may find that medicines that are designed to dissolve and be absorbed from under the tongue, eg sublingual glyceryl trinitrate (GTN) tablets, become less effective. This is because the tablets do not dissolve properly in a dry mouth. To resolve this, drink a mouthful of water before taking sublingual tablets.

Accidental overdose may produce narcosis with respiratory depression or atropine poisoning or both, particularly in children. Symptoms of overdose include dryness of the skin and mucous membranes, flushing, hypothermia and tachycardia, nystagmus, pinpoint pupils, hypotonic reflexes, lethargy, coma and severe respiratory depression. The onset of symptoms of overdose may be considerably delayed and respiratory depression may not become evident until as late as 12-30 hours after ingestion and may occur in spite of initial response to narcotic antagonists. Continuous observation should be maintained for at least 48 hours.

If respiratory depression develops, naloxone, a specific antidote, should be administered. The duration of action of naloxone hydrochloride is considerably shorter than that of diphenoxylate hydrochloride and repeated injections of the antidote may be required. Establishment of a patient airway and artificial ventilation may be needed. If the patient is not comatose, gastric lavage and administration of slurry of an activated charcoal may be indicated.

Getting the most from your treatment

  • It is important that you have lots to drink to prevent you from becoming lacking in fluid in the body (dehydrated). Drinking plain water is ideal, but juice and/or soup are also suitable. Try to avoid drinks that contain a lot of sugar, such as cola or pop, as they can sometimes make diarrhoea worse.
  • Oral rehydration salts can be taken to help prevent dehydration and replace lost salts. These are especially recommended for children and for people who are frail or who have underlying health problems. You can buy these from a pharmacy.
  • Eat small, light meals as soon as you are able. Plain foods such as wholemeal bread and rice are good foods to try eating first.
  • If your symptoms continue for more than 48 hours, speak with a doctor or pharmacist for advice if you have not already done so.
  • If your symptoms get worse, or if you develop a high temperature, or if you pass blood in the diarrhoea, you should ask your doctor or pharmacist for advice as soon as possible.
  • If you buy any medicines check with a pharmacist that they are suitable to take with co-phenotrope. This is because the risk of side-effects can be increased when co-phenotrope tablets are taken with some other medicines.
  • Do not take more than the prescribed dose. If you suspect that someone has taken an overdose of this medicine, or that a child has taken it by accident, go to the accident and emergency department of your local hospital straightaway. Take the container with you, even if it is empty.


  1. https://www.netdoctor.co.uk/medicines/digestion/a7032/lomotil-co-phenotrope/
  2. https://www.hpra.ie/img/uploaded/swedocuments/LicenseSPC_PA0899-007-001_19052015122117.pdf
  3. https://patient.info/medicine/co-phenotrope-tablets-for-diarrhoea
  4. https://www.hpra.ie/img/uploaded/swedocuments/PA%20899-7-1%20PIL%20-2162562-11062015155951-635696351923400000.pdf
  5. https://www.webmd.com/drugs/2/drug-6876/lomotil-oral/details
  6. https://www.rxlist.com/lomotil-drug.htm#precautions

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