How Lactulose Works in Harmony With Your Body: The Science Behind Duphalac (Lactulose)
Lactulose relieves constipation by drawing water into the bowel to make stools softer.1 Duphalac (lactulose) is an osmotic laxative that supports the colon’s natural rhythm.2 Understanding how it works can help you feel more confident about using it. This article walks through the science, step by step, in plain language.
What is lactulose, and where in the body does it work?
Lactulose is a sugar that your body cannot digest as there are no enzymes in the small intestine to break it down. Thus, it is poorly absorbed in the small intestine and travels through unchanged until it reaches the colon, or large intestine.3 The colon is where lactulose has its effect. 4
How does lactulose draw in water to soften stools?
Lactulose is an osmotic laxative which works by drawing water into the inside of the bowel.5 Increasing the water around hard, dry stools, softens the stool and helps make going to the toilet more comfortable as it is easier to pass.6
How does lactulose work together with your gut bacteria?
Lactulose also works hand in hand with the natural bacteria living in your colon. When lactulose reaches the colon, colonic bacteria ferment (break down) lactulose into natural organic acids.2 These acids lower the pH of the colon, making it slightly more acidic and thereby reducing the growth of bacteria that don’t like low pH. 7 At the same time, lactulose acts as an energy source for other bacteria, encouraging the growth of beneficial types such asBifidobacteria and Lactobacilli.7 Lactulose feeds these bacteria and increases their production of short-chain fatty acids.8 This is a natural process — your own gut bacteria are part of how lactulose works.
How do these effects work in harmony to get things moving?
The two effects work together – in synergy. The extra water drawn into the colon and the acids produced by fermentation both help stimulate the natural muscle movements of the colon, known as peristalsis, which move the stool along.2 The osmotic pull of water complements the acids that encourage the bowel muscles to contract, together helping to speed up the passage of stool.7 The result is that constipation is relieved and the colon’s natural rhythm is restored.2 As it supports processes your body already uses, lactulose works in harmony with your gut rather than against it.
How is this different from stimulant laxatives?
Lactulose belongs to a different group of laxatives than stimulants, and the two work in different ways. Osmotic laxatives such as lactulose draw water into the bowel to soften stool.5 Stimulant laxatives work differently — they act on the nerves and muscles of the gut to trigger movement, and they reduce the amount of water the bowel absorbs.5 Knowing this difference helps explain why lactulose is described as working with the body’s natural water balance and bacteria.
Does lactulose do more than relieve constipation?
In addition to softening stool, lactulose has a prebiotic effect in adults. By feeding beneficial bacteria, it helps create and maintain a healthy balance in the gut.2 It has been suggested that even small daily amounts can support beneficial bacteria and their helpful by-products.8 It is worth noting that this prebiotic benefit has only been studied in adults.2
What does this mean for you?
Understanding the mechanism helps you understand what to expect. As lactulose is fermented by gut bacteria, some wind (flatulence) can occur in the first few days; which generally settles after a few days.2 Lactulose is not an instant remedy — It is recommended you drink plenty of fluids while taking lactulose.1, 6
Is Duphalac right for you?
Duphalac (lactulose) is used to relieve constipation, and in adults, it can also support a healthy gut balance.2 It is suitable for many people, but not for everyone — for example, people with galactosaemia (a rare sugar disorder) should not take it.2 If you are unsure whether it is right for you, ask your pharmacist or doctor.
Important safety information
Like other osmotic laxatives, lactulose can sometimes cause wind, bloating, feeling sick or diarrhoea.2, 5 Taking higher doses than instructed may lead to diarrhoea and stomach pain, which can be eased by reducing the amount (i.e. dose) taken.2 Always read the patient leaflet and speak to a pharmacist or doctor if you have questions, or if your constipation does not improve.
Conclusion
Lactulose relieves constipation through a natural, step-by-step process: it travels unchanged to the colon, draws in water to soften stool, and is fermented by your gut bacteria into acids that lower the pH and encourage the bowel to move.1, 2, 7 Working alongside your own gut bacteria and natural muscle movements, Duphalac (lactulose) supports the colon’s natural rhythm.2 Your pharmacist or doctor can help you decide whether it is right for you.
FAQ
Lactulose works in the colon, or large intestine.4 It is not absorbed by the small intestine, so it travels to there unchanged.3, 4 In the colon, it draws in water and is fermented by gut bacteria.2
Lactulose is an osmotic laxative which means it pulls water into the inside of the bowel.5 Softer stools are easier and more comfortable to pass.6
No, lactulose is poorly absorbed after oral administration and reaches the colon unchanged.2 The small intestine doesn’t have the enzymes to break it down.3 This is why its effects are focused in the colon.4
Short-chain fatty acids are natural organic acids that gut bacteria produce when they ferment lactulose.7 These acids lower the pH of the colon.7 They also help encourage the bowel’s natural movement.7
Yes, lactulose has a prebiotic effect and feeds beneficial bacteria such as Bifidobacteria and Lactobacilli.7 In adults, this has been shown to help support a healthy gut balance.2 It has been shown that even small daily amounts can help support these bacteria.8
Lactulose is an osmotic laxative that draws water into the bowel.5 Stimulant laxatives act on the nerves and muscles of the gut and reduce how much water the bowel absorbs.5 They belong to different groups and work in different ways.5
Lactulose usually takes at least 2 days to work.1 It is not an instant remedy, so it may be a couple of days before you notice a difference.1 Talk to your doctor if your constipation does not improve.1
Wind happens because gut bacteria ferment lactulose, which produces gas as a natural by-product.4 This is most likely in the first few days and, as a rule, settles after a few days.2 Reducing the amount taken can help if side effects bother you.2
Lactulose can sometimes cause wind, bloating, feeling sick or diarrhoea.2, 5 These effects are linked to how it works in the gut.3, 4 If they bother you or do not settle, speak to a pharmacist or doctor.5
This article was written with the assistance of generative AI technology and reviewed for accuracy.
