Lactulose 3.3g/5ml Oral Solution 500ml

What Is Lactulose Oral Solution and How Does It Help Constipation?

Constipation is one of the most common digestive complaints in the UK, affecting people of all ages. If you have been struggling to pass stools regularly, or find them hard and uncomfortable to pass, lactulose oral solution is a well-established, clinically recognised option that can help restore normal bowel function. This 500ml bottle contains lactulose at a concentration of 3.3g per 5ml — a standard strength widely used across NHS settings and recommended by pharmacists throughout the country. You can browse our full range of constipation treatments if you want to compare your options before deciding.

Lactulose has been used for decades and has a well-documented safety profile. It is suitable for adults, children, and in many cases during pregnancy — though you should always check with a healthcare professional first. At just £8.99 for a 500ml bottle, it offers a cost-effective way to manage constipation without needing a prescription.

How Does Lactulose 3.3g/5ml Oral Solution Work in the Gut?

Lactulose belongs to a class of medicines called osmotic laxatives. Unlike stimulant laxatives, it does not force the bowel to contract. Instead, it works by drawing water into the large intestine, which softens the stool and increases its bulk — making it far easier to pass. Here is how the process unfolds:

• Lactulose is a synthetic disaccharide (a type of sugar) that the human gut cannot absorb.
• It passes intact into the colon, where it draws water across the intestinal wall by osmosis.
• Colonic bacteria ferment lactulose, producing short-chain fatty acids and gases.
• This fermentation lowers the pH of the colon, which further stimulates peristalsis (bowel movement).
• The combined effect softens and loosens the stool, typically within 24 to 48 hours.

Because lactulose is not absorbed into the bloodstream, it acts locally within the gut. This makes it a gentler choice compared with some other laxative types, particularly for people who need longer-term support.

Who Is Lactulose 3.3g/5ml Oral Solution Suitable For?

This solution is suitable for a wide range of people. It is particularly useful when dietary changes and increased fluid intake have not been enough to resolve constipation on their own. It is also used medically in the management of hepatic encephalopathy — a serious liver condition — though that use is typically supervised by a specialist. If you are also managing related digestive discomfort, our IBS and cramps range may be worth exploring alongside this product.

• Adults experiencing occasional or chronic constipation
• Children and infants (with appropriate dose adjustment and pharmacist guidance)
• Pregnant women who need a gentle laxative option (on medical advice)
• Older adults who may be more prone to constipation due to reduced mobility or medication side effects

How Does Lactulose Compare to Other Common Laxatives?

How Should You Store Lactulose Oral Solution and Is It Suitable Long-Term?

Store this product below 25°C, away from direct sunlight. Do not refrigerate — cold temperatures can cause the solution to crystallise. Once opened, use within the period stated on the label and keep the cap tightly closed. Keep out of reach and sight of children at all times.

If you are considering using lactulose oral solution for more than a few days, it is worth speaking to your GP or pharmacist. Prolonged use without medical review is not advised, as persistent constipation can sometimes indicate an underlying condition that needs investigation. Short-term use for occasional constipation is generally safe and well-tolerated for most people.

This product is a medicine. Speak to your doctor or pharmacist before using if you have an underlying medical condition or are taking other medicines.

What Is Lactulose 3.3g/5ml Oral Solution and What Is It Used For?

Lactulose 3.3g/5ml Oral Solution is an osmotic laxative used to treat constipation in adults and children. It works by softening the stool and encouraging the bowel to move more regularly. According to the NHS, lactulose is one of the first-line laxative options recommended for constipation, particularly when lifestyle measures such as increased fibre and fluid intake have not been sufficient. It is also used under specialist supervision for hepatic encephalopathy — a condition where the liver cannot adequately remove toxins from the blood, leading to a build-up that affects brain function.

What Do You Need to Know Before Using Lactulose Oral Solution?

Before taking this medicine, make sure it is appropriate for you. There are certain situations where lactulose should not be used, and others where caution is needed.

Do not use lactulose if you:

• Have galactosaemia (a rare inherited disorder affecting how the body processes galactose)
• Have a known bowel obstruction or suspected intestinal blockage
• Are allergic to lactulose or any of the other ingredients in the solution
• Have been told you have a condition requiring a low-galactose or low-lactose diet

Use with caution and speak to your pharmacist or GP if you:

• Are diabetic — lactulose contains small amounts of galactose and lactose
• Are pregnant or breastfeeding
• Have a history of inflammatory bowel disease
• Are taking other medicines, particularly those that affect electrolyte balance

Known drug interactions:

• No clinically significant interactions are documented at standard doses
• If you are taking neomycin or other antibiotics that affect gut flora, the effectiveness of lactulose in hepatic encephalopathy may be reduced
• Always inform your pharmacist of all medicines you are taking, including herbal remedies

How Should You Use Lactulose 3.3g/5ml Oral Solution?

Always use this medicine exactly as directed on the label or as advised by your pharmacist or doctor. The solution can be taken on its own or mixed with water or fruit juice if preferred. It is important to drink plenty of fluids throughout the day while taking lactulose — this helps the medicine work more effectively and reduces the risk of side effects such as bloating.

1. Measure the correct dose using the measuring cup or spoon provided.
2. Take the dose orally — swallow it directly or mix with a small amount of water or juice.
3. Drink at least 6–8 glasses of water throughout the day.
4. Take at the same time each day to help establish a routine.
5. Allow 24–48 hours for the medicine to take effect before adjusting your dose.

Doses for children should always be confirmed with a pharmacist or GP. If you are unsure about the right dose for your child, our baby and toddler health range includes additional resources and products to support your child's wellbeing.

What Are the Possible Side Effects of Lactulose Oral Solution?

Like all medicines, lactulose can cause side effects, although not everyone experiences them. Most side effects are mild and tend to improve after the first few days of treatment as your body adjusts.

Common side effects:

• Flatulence (wind)
• Bloating or abdominal distension
• Abdominal cramps or discomfort
• Nausea, particularly when starting treatment

Less common side effects:

• Diarrhoea — especially if the dose is too high
• Electrolyte imbalance (with prolonged high-dose use — more relevant in hepatic encephalopathy treatment)
• Vomiting

If you experience severe diarrhoea, stop taking lactulose and contact your pharmacist or GP. Prolonged diarrhoea can lead to dehydration and electrolyte disturbances. You may also find our diarrhoea treatments helpful if this occurs.

How Should You Store Lactulose 3.3g/5ml Oral Solution?

• Store below 25°C in a dry place away from direct sunlight and heat.
• Do not refrigerate — cold temperatures may cause crystallisation of the solution.
• Keep the bottle tightly closed when not in use.
• Keep out of the sight and reach of children.
• Do not use after the expiry date printed on the label.
• Do not dispose of medicines via wastewater or household waste — return unused medicine to your pharmacy.