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Generic Name: Lactulose
Product Name: Actilax


Used to treat constipation. Also used in the treatment of a specific disorder of brain function (called portal systemic encephalopathy – PSE) caused by many different types of liver disease.


Actilax is taken orally and reaches the large bowel without being absorbed into the bloodstream. Here, it is degraded by the normal bacteria found in the bowel, and this changes the pH, making it more acidic. This has two effects: one is to increase the amount of water in the bowel, which makes the stools softer and allows defecation to occur. The other is to remove harmful ammonia from the system and expel it in faeces, preventing the brain from being exposed to it as happens in PSE.

Dose advice

Chronic constipation: The dose depends on the severity of the constipation, and is different for adults and children.Adults:

  • Begin with initial dose of 15-30ml once a day.
  • The maximum dose is 45ml daily.
  • After three days a maintenance dose of 10-25ml daily should be commenced.

Children:Actilax should only be used in children under medical supervision:Initial doses:

  • 7-14 yrs: 15ml.
  • 1-6 yrs: 10ml.

Maintenance doses:

  • – 7-14 yrs: 10ml.
  • 1-6 yrs: 5-10ml.

Portal systemic encephalopathy:

  • 30-45ml 3-4 times daily.
  • Initially the medication may be given more often, even up to hourly, but this will be reduced to the above dose as soon as possible.

Unconscious patient:

  • If the patient is unconscious it may be necessary to give Actilax in enema form until the patient regains consciousness and can take it orally.
  • 300ml of Actilax is mixed with 700ml of water.



Common side effects

Distension, flatulence and intestinal cramps occur in 20% of cases, which are usually mild and transient. Excessive dosage can lead to diarrhoea, which can lead to fluid loss and electrolyte imbalance if left untreated.

Uncommon side effects

For further information talk to your doctor.

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Posted On: 22 July, 2003
Modified On: 14 June, 2007

Created by: myVMC