Lactulose
Content date: 15 November 2026
Lactulose softens stool for constipation. In advanced liver disease, it also helps treat and prevent hepatic encephalopathy, which can cause confusion and drowsiness. These uses require different plans.
Your next step
Check your written prescription and monitoring plan. If anything is unclear, ask your care team before changing a dose.
Get urgent help: Seek urgent assessment for new confusion, unusual sleepiness, inability to wake normally, or severe or persistent abdominal pain, especially with vomiting.
How do I use it?
- Measure the prescribed millilitres with a medicine cup or oral syringe, not a kitchen spoon. Take with or without food; mixing with water or juice may help the taste. Constipation relief can take two to three days. For hepatic encephalopathy, follow your team’s adjustment plan to achieve two to three soft stools daily—not watery diarrhoea. Do not copy another patient’s dose.
How do I store it?
- Keep the bottle closed and away from children. Follow your product’s temperature and light instructions; do not freeze. Ask a pharmacist about an unusually dark or cloudy solution or storage after opening.
What tests do I need?
- During encephalopathy treatment, your team checks bowel pattern, hydration, thinking and blood salts as needed. A stool diary helps dose review. Excess diarrhoea can cause dehydration and low potassium; older or frail people may need closer monitoring.
Possible side effects: what to expect
- Not everyone gets side effects. Wind, bloating, cramps or nausea may occur, especially when starting treatment. Discuss troublesome symptoms; for hepatic encephalopathy, follow your dose plan to reach the soft-stool target.
- Excess dosing or persistent diarrhoea can cause dehydration and sodium or potassium disturbances. Repeated watery stools, dizziness or reduced urine need prompt advice. New confusion requires urgent assessment, not an assumption that it is a mild side effect.
Important points
- Drink the amount of fluid permitted in your care plan and tell your clinician about diabetes. Lactulose contains residual sugars: if you have galactosaemia or must follow a medically prescribed low-galactose diet, do not start it before the prescriber or pharmacist checks it, because the product may be contraindicated. This differs from ordinary lactose intolerance. Do not stop encephalopathy prevention just because thinking has improved; contact the team for dose advice if side effects interfere.
My prescribed plan - complete with the team
Brand / device: ........................ | Dose and how I take or use the medicine: ........................
Next dose: ........................ | Next blood tests: ........................
Team contact: ........................
Brand / device: ........................ | Dose and how I take or use the medicine: ........................
Next dose: ........................ | Next blood tests: ........................
Team contact: ........................
When to get help
Seek urgent assessment for new confusion, unusual sleepiness, inability to wake normally, or severe or persistent abdominal pain, especially with vomiting.
Contact your team promptly for repeated watery stools, dizziness, reduced urine, or failure to meet your agreed stool target.