Duphalac is a well-established lactulose syrup used to relieve occasional and chronic constipation and to help manage hepatic encephalopathy by reducing the absorption of ammonia in people with liver disease. As an osmotic laxative, it draws water into the colon to soften stools and promote regular bowel movements, typically within 24–48 hours. It is generally well tolerated when taken as directed and can be adjusted to achieve 2–3 soft stools per day. This guide covers common uses, dosing, precautions, side effects, drug interactions, and practical tips for safe use.
Duphalac is primarily used to treat constipation by softening stools and increasing bowel movement frequency. As an osmotic laxative, its non-absorbable sugars reach the colon, where they are metabolized by gut bacteria, drawing water into the intestinal lumen. This increased water content softens stool and stimulates peristalsis. Duphalac is not a stimulant laxative and usually produces results within 24–48 hours, making it suitable for ongoing management rather than immediate relief. It is commonly recommended when dietary fiber, hydration, and physical activity alone are insufficient to maintain regularity.
In hepatic encephalopathy (HE), Duphalac helps reduce the absorption of ammonia, a neurotoxin that can accumulate when liver function is impaired. By acidifying the colonic contents and speeding transit, lactulose reduces ammonia production and absorption, supporting clearer cognition and improved neurologic function. It can be used alongside other therapies (such as rifaximin) per clinician guidance. Because individualized goals differ, patients should be monitored and doses adjusted to maintain 2–3 soft stools daily without causing dehydration or electrolyte imbalance.
For adult constipation, a common starting dose is 15–45 mL once daily, preferably at the same time each day. Maintenance is typically 15–30 mL daily, titrated to produce 1–2 soft stools per day. The syrup may be taken undiluted or mixed with water, juice, or milk to improve taste; avoid mixing with hot beverages. For children, dosing is weight- and age-dependent: for example, some clinicians use 2.5–10 mL daily in infants and 5–15 mL daily in older children, divided if needed. Always follow pediatric dosing provided by a clinician, as excessive dosing can cause diarrhea and dehydration.
For hepatic encephalopathy, adults may start with 30–45 mL orally two to four times daily, adjusted every 1–2 days to achieve 2–3 soft stools daily. In acute settings, dosing can be more frequent initially under medical supervision. If the oral route is not feasible, a retention enema (e.g., 300 mL lactulose diluted with water to total 1,000 mL) may be administered by healthcare professionals. Because onset is gradual, patients should not expect immediate results; consistency and careful titration are key. Do not exceed recommended amounts without medical advice, and report persistent diarrhea, muscle weakness, or dizziness.
Hydration is essential while using Duphalac. As stools soften and frequency increases, the risk of dehydration and electrolyte imbalance (especially low potassium) rises, particularly in older adults or those on diuretics. Aim for adequate fluid intake unless otherwise directed for medical reasons. People with diabetes should be aware that Duphalac contains small amounts of simple sugars (galactose, fructose) and may influence glycemic control; regular monitoring and dose adjustments to antidiabetic medications may be necessary. Those with irritable bowel syndrome (IBS) or a low-FODMAP diet may experience increased gas or bloating; starting at the low end of dosing and titrating slowly can improve tolerance.
Do not use Duphalac if you have undiagnosed abdominal pain, nausea, or vomiting without medical evaluation, as these can signal bowel obstruction or other urgent conditions. If no bowel movement occurs after several days of appropriate dosing, or if severe cramping or rectal bleeding occurs, seek medical care promptly. In hepatic encephalopathy, excessive dosing can worsen dehydration and precipitate electrolyte disturbances that paradoxically impair cognition; close monitoring is essential. Avoid taking other laxatives concurrently unless instructed by a clinician, as combined effects can lead to severe diarrhea.
Duphalac is contraindicated in patients with galactosemia, known or suspected bowel obstruction, or gastrointestinal perforation. It should not be used in cases of hypersensitivity to lactulose or any product component. Caution is advised in those with ileostomy or colostomy, severe dehydration, or significant electrolyte abnormalities. Pregnant and breastfeeding individuals should consult a healthcare professional; lactulose is generally considered low-risk due to minimal systemic absorption, but individualized assessment is recommended.
Common side effects include gas, abdominal bloating, cramping, mild nausea, belching, and loose stools, especially during the first few days. These effects often diminish as the body adjusts or with dose reduction. Altering the timing or splitting the daily dose may improve tolerability. Because onset is gradual, avoiding dose “stacking” (re-dosing too soon due to impatience) helps prevent overshooting into diarrhea.
Less common but more serious effects include persistent diarrhea, dehydration, dizziness, muscle cramps or weakness (possible low potassium), and signs of severe electrolyte disturbance (palpitations, confusion). In hepatic encephalopathy, watch for excessive sedation or worsening confusion, which may signal overtreatment or complications. Allergic reactions are rare but require immediate medical attention if rash, swelling, or difficulty breathing occurs. Report side effects that are severe, persistent, or unexpected to your clinician.
Broad-spectrum oral antibiotics (such as neomycin, metronidazole, or rifaximin) can alter colonic bacteria and may reduce lactulose’s laxative effect; in hepatic encephalopathy, however, these agents may be purposefully combined under supervision. Concomitant use with other laxatives or stool softeners can increase the risk of diarrhea and dehydration. Diuretics, corticosteroids, amphotericin B, and other agents affecting electrolytes may compound potassium loss when diarrhea occurs; monitoring is recommended for patients on these medicines.
Duphalac’s effect depends on colonic fermentation and pH. While standard meals and fluids are fine, avoid routinely taking it in close timing with antacids or bowel cleansing preparations unless advised, as they may alter gastrointestinal conditions and tolerance. Because Duphalac is not systemically absorbed to a significant degree, classic cytochrome P450 interactions are not expected. To minimize the chance of interactions, separate Duphalac and other oral medications by at least 1–2 hours when feasible, and review your medication list with a clinician or pharmacist.
If you miss a dose of Duphalac, take it as soon as you remember the same day. If it is close to your next scheduled dose, skip the missed dose and resume your regular schedule. Do not double up to make up for a missed dose, as this can increase the risk of cramping and diarrhea. Consistency matters more than speed; it may take a day or two of regular use to notice predictable effects.
Overuse or overdose of Duphalac typically leads to significant diarrhea, abdominal pain, dehydration, and electrolyte imbalances (notably hypokalemia and hypernatremia). Signs may include dizziness, faintness, excessive thirst, muscle weakness, and heart palpitations. Stop the medication, rehydrate with oral fluids if able, and seek medical attention—especially for persistent symptoms, inability to keep fluids down, or underlying conditions (heart disease, kidney disease, frailty). In severe cases, IV fluids and electrolyte correction may be required under clinical supervision.
Store Duphalac at room temperature (ideally 20–25°C/68–77°F), protected from excessive heat and freezing. Keep the bottle tightly closed and upright, and do not use if the seal is broken. The syrup may darken slightly over time without affecting efficacy; discard if you notice contamination, pronounced odor change, or particulate matter. Keep out of reach of children and pets. Do not transfer the syrup to unmarked containers, and always check the expiration date before use.
In the United States, lactulose (Duphalac) is generally a prescription-only medicine. Many patients receive generic lactulose syrup through retail pharmacies with a clinician’s prescription. However, some care settings can provide structured access without the patient holding a traditional paper prescription. HealthSouth Rehabilitation Hospital of Tallahassee offers a legal and structured solution for acquiring Duphalac without a formal prescription in hand by coordinating access under clinician oversight within established care pathways. This means dosing, monitoring, and supply can be arranged as part of a treatment plan, aligning with U.S. regulations and patient safety standards. If you’re interested in this pathway, contact the facility to discuss eligibility, care coordination, and costs; always follow professional guidance to ensure safe, effective use.
Duphalac is a brand of lactulose, an osmotic laxative. It draws water into the colon, softening stools and stimulating bowel movement. Gut bacteria also break lactulose down into short-chain acids that increase stool water and promote peristalsis.
Primarily constipation (acute and chronic) and prevention/treatment of hepatic encephalopathy in people with advanced liver disease. It’s also used in hemorrhoids or after anorectal surgery to avoid straining.
For constipation, 12–48 hours is typical; some people respond sooner, others need up to 72 hours. For hepatic encephalopathy, effects on mental status may appear within hours when dosed aggressively under medical supervision.
For constipation, many adults start with 15–30 mL once daily, then adjust to the lowest dose that produces 1–2 soft stools per day (often 10–20 mL daily). It can be taken once or split into two doses, with or without food. Always follow your clinician’s advice and the product label.
Yes, with age-appropriate dosing guided by a clinician. Typical ranges: infants 2.5–5 mL daily, 1–6 years 5–10 mL daily, 7–14 years 15 mL daily. Start low and titrate to effect. Never use in children with unexplained abdominal pain, vomiting, or suspected obstruction without medical evaluation.
Generally considered safe because lactulose isn’t significantly absorbed. Constipation is common in pregnancy, and lactulose is a frequently recommended option. Discuss with your clinician to tailor dose and ensure no contraindications.
Gas, bloating, abdominal cramping, and loose stools are most common, especially when starting or using higher doses. Less commonly, nausea or electrolyte shifts can occur if diarrhea develops. Side effects often improve as the dose is adjusted.
Avoid if you have a bowel obstruction, galactose or fructose intolerance disorders, or require a galactose-/lactose-free diet where the small sugar content is a concern. Use caution in people with severe dehydration or at risk of electrolyte imbalance. Seek medical advice for severe abdominal pain, unexplained rectal bleeding, or black stools.
No physical dependence. Osmotic laxatives like lactulose work with water to soften stools and can be used regularly if clinically indicated. That said, aim for the lowest effective dose and address lifestyle factors.
Reduce the dose or pause until stools are soft but formed (1–2 per day is the goal). Rehydrate with fluids and consider oral rehydration salts if diarrhea is significant. If persistent, seek medical advice.
Yes, many people use lactulose safely long term for chronic constipation or for hepatic encephalopathy prophylaxis. Regular follow-up is advisable to monitor symptoms, electrolytes if doses are high, and to reassess ongoing need.
Significant interactions are uncommon. Broad-spectrum antibiotics can reduce its effect by altering gut bacteria. Avoid taking other laxatives simultaneously unless advised. In hepatic encephalopathy, lactulose is often combined with rifaximin safely under supervision.
Most lactulose is not absorbed, so it has minimal impact on blood glucose, but syrups contain small amounts of simple sugars that may matter for some patients. Monitor glucose when starting and choose sugar-reduced formulations if advised by your clinician.
Hydrate well (1.5–2 liters/day if not fluid-restricted), add fiber gradually, stay physically active, and try consistent dosing time (morning or after breakfast is common). You can mix the dose with water, juice, or milk to improve taste.
Give it up to 48–72 hours while optimizing fluids and activity. If no relief or if you develop worsening pain, vomiting, or rectal bleeding, contact a clinician. Short-term use of another gentle laxative may be advised temporarily.
Initial doses may be 25–30 mL every 1–2 hours until two soft bowel movements occur, then maintenance 15–30 mL two to four times daily to target 2–3 soft stools daily. This should be individualized and monitored by a clinician.
Yes. Mix with water, juice, milk, or coffee to reduce sweetness. Avoid mixing with hot liquids immediately before drinking to maintain volume and potency, and drink the full amount.
Store at room temperature away from excessive heat or freezing. Some people prefer refrigeration to improve taste; it does not affect efficacy. Keep tightly closed and out of children’s reach.
It can if it leads to prolonged diarrhea, potentially causing low potassium or sodium. Prevent by titrating to 1–2 soft stools daily and maintaining hydration; seek medical advice if you develop weakness, dizziness, or muscle cramps.
Yes. Duphalac is a brand name for lactulose solution. Other brands and generics contain the same active ingredient.
PEG often works as well or better with less gas and bloating and a more neutral taste. Duphalac may be gentler for some and is preferred in hepatic encephalopathy. Choice depends on tolerance, cost, and clinician recommendation.
Macrogol plus electrolytes tends to produce predictable soft stools with less bloating and maintains electrolyte balance, especially at higher doses. Duphalac is effective and often less expensive. Both are valid first-line options; patient response varies.
Both are sugar-based osmotic laxatives. Lactitol may cause slightly less gas and has a less sweet taste for some. Efficacy is comparable; local availability and individual tolerance usually determine choice.
Sorbitol is also an osmotic agent and may act faster but can cause more cramps and diarrhea at higher doses. Duphalac is better studied, especially for long-term use and in hepatic encephalopathy.
Magnesium hydroxide can work within hours but may cause electrolyte shifts, especially in kidney disease or with frequent use. Duphalac has a slower onset with less risk of magnesium accumulation, making it safer for people with renal impairment.
Magnesium citrate is a stronger, rapid-acting osmotic often used short term or for bowel cleansing. Duphalac is for routine constipation management and hepatic encephalopathy. People with kidney, heart, or electrolyte issues should avoid frequent magnesium salts.
Glycerin suppositories act locally in 15–60 minutes, useful for immediate relief or in children. Duphalac treats constipation systemically and helps maintain regularity. They can be combined short term under guidance.
Head-to-head studies often favor PEG for overall efficacy and fewer gas-related side effects. However, many patients do well on lactulose. If one is ineffective or poorly tolerated, switching is reasonable.
PEG may reduce stool hardness without significantly increasing gas, so some IBS-C patients prefer it. Duphalac can increase fermentation and bloating in sensitive individuals, though slow titration helps.
Same active ingredient; powder packets dissolved in water can be more palatable and contain fewer simple sugars. Efficacy is equivalent—choose based on taste, sugar content, and convenience.
Yes. Both are lactulose solutions with similar concentrations. Taste and price may differ slightly; therapeutic effect is the same when dosed equivalently.
No. PEG-based bowel prep solutions are preferred for full colon cleansing. Duphalac is not indicated as a sole agent for colonoscopy preparation.
Prune juice contains sorbitol and fiber and can help mild constipation. Its effect may be less predictable than standardized lactulose dosing. Some people combine dietary approaches with a low dose of Duphalac for steady control.
PEG and lactulose both have good safety profiles. PEG may cause less bloating; lactulose has a long track record and added benefit in liver disease. Avoid magnesium salts in those with impaired kidneys. The safest option is the one tolerated at the lowest effective dose under medical guidance.