Chronulac Syrup

Generic name: Lactulose.

Other brand names: Cephulac, Cholac, Constilac, Duphalac, Enulose.

Chronulac Syrup is a laxative. It works by increasing the stool’s fluid content, promoting bowel evacuation. 

Quick Facts About Chronulac Syrup


Used to treat constipation. For chronic constipation, increases the number and frequency of bowe movements.

Chronulac Syrup Dosage

Take exactly as prescribed. May take with water, fruit juice, or milk. Do not take if you are on a low-galactose diet.

  • Usual adult dose: 1 to 2 tablespoonfuls (15 to 30 milliliters) per day, up to 60 milliliters per day.
  • Usual child dose: for portal-systemic encephalopathy only — 30 to 45 milliliters 3 or 4 times per day.
  • Missed dose: take as soon as possible, do not double doses.

Chronulac Syrup Side Effects

Overdose symptoms:

abdominal cramps, diarrhea. If you suspect an overdose, immediately seek medical attention.

More common side effects: diarrhea, gas, intestinal cramps, nausea, potassium and fluid loss, vomiting.

No known less common or rare Chronulac Syrup side effects.


Inform your doctor before combining Chronulac Syrup with:

non-absorbable antacids such as Maalox and Mylanta.

No known food/other substance interactions.

Special Cautions

If pregnant or planning to become pregnant, inform your doctor immediately. May appear in breast milk; could affect a nursing baby.

No special precautions apply to seniors.

Not generally prescribed for children except in the case of portal-systemic encephalopathy.

  • May take 24 to 48 hours to have a normal bowel movement.
  • Use with caution if you are diabetic.
  • Notify your doctor of unusual diarrhea.

Note: provides accurate and independent information prescription pills, over-the-counter medicines and natural products. This material is provided for educational purposes only and is not intended for medical advice, diagnosis or treatment. If you have questions about  dosage, or Chronulac Syrup side effects, please contact your healthcare provider.