Duphalac (Lactulose)
Also sold as: Duphalac, Lactolax, Looz, Laxolac, Gulac
Pregnancy
Cat B
Lactation
Safe
Schedule
OTC
Forms
Syrup/Solution 3.35g/5mL (66.7% w/v) +1
Indications
- Constipation — chronic and acute
- Hepatic encephalopathy — prevention and treatment (reduces ammonia production)
- Constipation in pregnancy
- Constipation in elderly and paediatric patients
Adult Dosing
Constipation
15-30 mL PO once daily or BD
Adjust to produce 2-3 soft stools/day
May take 2-3 days to see effect
Hepatic encephalopathy (treatment)
30-45 mL PO TDS-QID
Target 2-4 loose stools/day to acidify colon and trap ammonia (NH3 → NH4+)
Hepatic encephalopathy (prevention)
15-30 mL BD, titrated
Pediatric Dosing
Safe and effective across all paediatric age groups. Adjust dose to produce soft stools.
Renal Dose Adjustment
| CrCl / eGFR | Dose Adjustment |
|---|---|
| Any | No adjustment — not absorbed systemically |
Hepatic Adjustment
KEY USE in hepatic disease — reduces gut ammonia; no dose adjustment needed except titrate to stool target
Pregnancy & Lactation
Pregnancy: Category B
First-line laxative in pregnancy — not absorbed, safe for fetus. Preferred over stimulant laxatives.
Lactation: Safe
Not absorbed systemically; safe during breastfeeding.
Top Drug Interactions
| Interacting Drug | Effect | Severity |
|---|---|---|
| Neomycin / Antibiotics | Some antibiotics may reduce lactulose efficacy in HE by altering gut flora | Minor |
| Antacids (non-absorbable) | May reduce lactulose laxative effect | Minor |
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Side Effects
Common
- Flatulence (very common initially)
- Abdominal cramps
- Diarrhea (if excessive dose)
- Nausea
- Electrolyte imbalance (prolonged overuse — rare)
Serious / Discontinue If
- Dehydration and electrolyte imbalance (prolonged excessive use)
- Hypernatremia (diabetes insipidus patients — free water deficit)
Contraindications
- Galactosaemia (contains galactose and lactose)
- Intestinal obstruction
- Appendicitis
- Abdominal pain of unknown cause
Available Indian Brands
| Brand | Manufacturer | Price (approx) |
|---|---|---|
| Duphalac 100mL | Abbott | 100mL ₹110 |
| Looz 300mL | Lupin | 300mL ₹195 |
| Lactolax 200mL | Sun Pharma | 200mL ₹135 |
| Laxolac 100mL | Alkem | 100mL ₹95 |
Monitoring Required
- Stool frequency (target 2-3/day for constipation; 2-4 loose/day for HE)
- Serum sodium, potassium (prolonged high-dose)
- Serum ammonia (for hepatic encephalopathy monitoring)
Patient Counseling Points
- Takes 1-2 days to work — do not increase dose too quickly
- Mix with juice, water or milk if preferred to improve taste
- Flatulence is very common initially — usually settles after 1 week
- For hepatic encephalopathy: take regularly even when feeling well — prevents hospital admission
- Contact doctor if diarrhea becomes severe or prolonged
- Not habit-forming — safe for long-term use
Stop Googling drug references mid-consultation
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Clinically reviewed by: Dr. Rajesh Nair, DM (Gastroenterology), Senior Consultant
Last reviewed: 2026-04-01
References
- BNF — Lactulose
- AASLD Hepatic Encephalopathy Guidelines 2022
- ACG Chronic Idiopathic Constipation Guidelines
- WHO Maternal Constipation Guidelines