Duphalac (Lactulose) in Spain: What It Is For
Medically Reviewed by Dr. Pedro Yelamo Vera, MD
Licensed Physician No. 484814280 · Official Medical College of Bizkaia (Spain)Last reviewed: 29 October 2026
Duphalac is lactulose, a laxative syrup for constipation and soft stools with piles. Why it causes wind, diabetes notes and why Spain needs a prescription.
You don't have to figure this out alone
Dr. Pedro Yelamo Vera is an independent, bilingual GP licensed in Spain. Book a 15-minute video consultation in English or Spanish for €50, with a private electronic prescription issued under Spanish law when clinically appropriate.
Duphalac is the Spanish brand of lactulose, a sweet liquid laxative. It is a man-made sugar that softens stools by drawing water into the bowel. Doctors use it for constipation and to keep stools soft with piles or an anal tear. Specialists also use it in severe liver disease. In Spain it needs a prescription.
- Duphalac (lactulose) is an osmotic laxative syrup. Gut bacteria break it down, which pulls water into the stool.
- It treats constipation and keeps stools soft with haemorrhoids, anal fissures or after anal surgery.
- Wind and bloating are common in the first few days. It can take two to three days to work.
- In Spain both Duphalac packs (bottle and sachets) need a prescription. In the UK it is sold in pharmacies.
Dr. Pedro Yelamo Vera is a GP licensed in Spain (Colegiado No. 484814280).
For a medical emergency, call 112 or go to the nearest local emergency department. Do not wait for a video consultation or an online reply.
What is Duphalac used for?
The Spanish leaflet lists three uses:
- Constipation in adults and children.
- Soft stools when passing them hurts: piles (haemorrhoids), an anal fissure, a fistula or abscess, or after surgery on the back passage. Soft stools mean less straining and less pain.
- Hepatic encephalopathy: confusion caused by severe liver disease. This use is for people with liver disease, under a specialist. The amounts are much higher and are set by the liver team.
Duphalac comes as a syrup in a bottle and as single sachets of liquid. It is lactulose only; there is no flavour or colour added.
How does lactulose work, and why does it cause wind?
Lactulose is a sugar that your small bowel cannot absorb. It reaches the large bowel intact. There, normal gut bacteria ferment it into small acids. These acids pull water into the bowel and make the stool softer and bulkier.
The same fermentation makes gas. That is why wind, bloating and gurgling are common in the first days. The Spanish leaflet says this usually settles within a few days. It also says you may need two to three days to notice an effect. So it is not a laxative for quick relief.
Duphalac, lactulose, Enulose: which name is which?
| Name | What it is | Where |
|---|---|---|
| Duphalac | Lactulose syrup or liquid sachets | Spain (prescription); also sold as Duphalac in the UK and Ireland |
| Lactulosa Lainco | Generic lactulose | Spain (prescription) |
| Lactulose (generic) | Lactulose oral solution | UK (pharmacy), US (prescription) |
| Enulose, Generlac | Lactulose oral solution | US (prescription) |
| Movicol (macrogol) | A different osmotic laxative, a powder | Spain, UK, Ireland |
If lactulose did not suit you because of wind, a doctor may suggest macrogol instead. Macrogol (Movicol) is a powder that gut bacteria do not ferment, so it tends to cause less wind.
Do you need a prescription for Duphalac in Spain?
Yes. The AEMPS CIMA database lists both Duphalac packs, the bottle and the sachets, as a medicamento sujeto a prescripción médica. The generic lactulose on sale in Spain is listed the same way. A pharmacy needs a Spanish prescription, which can be a private electronic one.
This is different from the UK, where adults can buy lactulose in a pharmacy. In the US, lactulose is prescription-only too.
Hard stools that hurt, piles, or constipation that will not shift?
You can book a video visit with a GP licensed in Spain, in English or Spanish. He checks for warning signs and explains whether lactulose, another laxative or a change in habits suits you.
Lactulose and sugar: diabetes, intolerances and children
- Diabetes: the leaflet says the usual amounts for constipation should not be a problem. The much higher liver amounts may affect blood sugar.
- Galactosaemia: do not take it. It is a rare inherited condition, usually found in babies.
- Rare sugar intolerances: Duphalac contains traces of lactose, galactose and fructose. People with hereditary galactose or fructose intolerance, or glucose-galactose malabsorption, should not take it. If you are lactose intolerant, ask first.
- Sulfites: it may contain traces that, rarely, cause a serious allergic reaction.
- Children: the leaflet says a laxative should be the exception in children, and only with a doctor's advice.
- Pregnancy and breastfeeding: the leaflet says it can be used, as very little enters the blood.
What Duphalac does not treat
- Tummy pain with no clear cause. The leaflet says this needs checking first, to rule out a blocked or torn bowel.
- A blocked bowel or a risk of a tear. It must not be used.
- Diarrhoea. It would make it worse.
- Bloating on its own. Lactulose tends to add wind, not relieve it.
- Liver disease itself. In hepatic encephalopathy it is part of a specialist plan, not a home treatment.
Read about the usual causes on our constipation page. If piles are the reason you need soft stools, see our haemorrhoids page.
Side effects and when to see a doctor
Loose stools are very common, and are a sign the amount may be too high. Wind, tummy ache, nausea and vomiting are common. Long use at high amounts can upset your body salts, such as potassium. Skin rash and itching are rare. See a doctor if:
- There is blood in your stools, or they are black.
- You are losing weight without trying.
- You have strong tummy pain or keep vomiting.
- You are over 50 and constipation is new, or comes and goes with diarrhoea.
- There is no change after a few days, or things get worse.
- You have frequent diarrhoea and feel weak or very tired, or your heart beats oddly.
Call 112 if you have severe tummy pain and cannot pass wind, swelling of the face, lips or throat, or trouble breathing. Call too if someone with liver disease becomes confused or very drowsy.
Talking it through with a doctor by video
Dr. Yelamo is a GP licensed in Spain. He sees adults, children and pregnant patients by video, every day from 07:30 to 20:30 (Spain time). In the visit he will:
- Ask about your stools, your diet, your fluids and the medicines you take.
- Check for warning signs that need tests or an in-person exam.
- Explain whether lactulose, macrogol, fibre or another option fits you best.
- Tell you when to stop, and what to do if wind or loose stools get in the way.
He does not promise any test or prescription before the visit. Where clinically appropriate, following a genuine evaluation. Treatment and prescriptions are issued solely at the doctor's discretion based on evidence-based clinical guidelines.
A prescription is never guaranteed: it is issued only where clinically appropriate after a genuine evaluation, as a private electronic prescription under Spanish law. This service is for urgent, non-emergency care. In an emergency, call 112.
See how the Urgent Care video visit works. It lasts 15 minutes and costs €50.
This guide is general information. It does not replace the package leaflet or the advice of your doctor or pharmacist.
Frequently asked questions
Is Duphalac the same as lactulose?
Yes. Duphalac is a brand of lactulose syrup. Generic lactulose works the same way. In the US it is sold as Enulose, Generlac or plain lactulose.
Can I buy Duphalac without a prescription in Spain?
No. CIMA lists both Duphalac packs, and the generic lactulose sold in Spain, as prescription-only. In the UK adults can buy it in a pharmacy.
How long does Duphalac take to work?
It can take two to three days to notice an effect. It is not meant for quick relief. See a doctor if nothing changes after a few days.
Why does lactulose give me wind?
Gut bacteria ferment lactulose, and that makes gas. Wind and bloating are common in the first days and usually settle. If they do not, a doctor may suggest another laxative.
Can I take Duphalac if I have diabetes?
The leaflet says the usual amounts for constipation should not be a problem. The much higher amounts used in liver disease may affect blood sugar, so ask your doctor.
Why is lactulose used in liver disease?
In severe liver disease, lactulose helps lower ammonia from the gut, which can cause confusion. This use is set and followed by a specialist, not started at home.
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This content is written and reviewed by a licensed physician with reference to the following official health authorities.
