Lactulose for constipation
Granskad av Sid DajaniSenast uppdaterad av Michael Stewart, MRPharmSLast updated 16 okt 2023
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Lactulose can take up to 48 hours to have an effect.
If you find the medicine makes you feel queasy, mix your dose with some water or fruit juice. Alternatively, take your doses with a meal.
Eating a healthy diet, drinking plenty of water and getting regular gentle exercise can all help prevent constipation.
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About lactulose
Typ av medicin | An osmotic laxative |
Används för | Förstoppning |
Tillgänglig som | Oral liquid medicine, liquid sachets |
Förstoppning is a common problem. It can mean either going to the toilet less often than usual to empty your bowels, or passing hard or painful stools. Constipation can be caused by a number of things. Not eating enough fibre or not drinking enough fluid can cause constipation. Some conditions (such as pregnancy) can cause constipation, as can a lack of exercise or movement (such as being ill in bed) and some medicines.
Often, increasing the amount of fibre in your diet (such as by eating more fruit, vegetables, cereals, and wholemeal bread) and drinking plenty of water each day can effectively prevent or relieve constipation. You will have been recommended lactulose, a laxative, to help relieve constipation if you cannot increase the fibre in your diet or if this is insufficient. Lactulose works by drawing fluid into your bowel, which makes your stools softer and easier to pass. It is available on prescription, and it can also be bought without a prescription at pharmacies.
Lactulose also changes the acidity of the stools and this helps to discourage the growth of some germs (bacteria) present in the bowel. Because of this, lactulose is also prescribed for people with a liver disease called hepatic encephalopathy. If you have been prescribed it for this reason, ask your doctor if you need further information about the medicine.
Before taking lactulose
Tillbaka till innehållSome medicines are not suitable for people with certain conditions, and sometimes a medicine may only be used if extra care is taken. For these reasons, before you start taking lactulose it is important that your doctor or pharmacist knows:
If you are so constipated that you think you may have a blockage.
If you are unable to digest milk sugar (lactose intolerant).
If you have a condition called galactosaemia, where your body cannot process galactose.
If you are pregnant or breastfeeding. Lactulose is not known to be harmful to a baby, but while you are expecting or feeding a baby, you should only take medicines on the recommendation of a doctor.
If it is intended for a child. This is because laxatives should only be given to children on the advice of a doctor or healthcare professional.
Om du tar andra läkemedel, inklusive de som kan köpas utan recept, samt växtbaserade och komplementära läkemedel.
If you have ever had an allergic reaction to this or to any other medicine.
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How to take lactulose
Tillbaka till innehållBefore you start the treatment, read the manufacturer's printed information leaflet from the pack. It will give you more information about lactulose and will provide you with a full list of the side-effects which you may experience.
Take lactulose exactly as your doctor tells you to, or as directed on the pack. The usual dose for constipation in an adult is 15 ml (three 5 ml spoonfuls) twice daily, although the dose you are advised to take may be different from this as it will be adjusted to suit your needs.
If a doctor or healthcare professional has recommended lactulose for your child, check the label on the pack carefully to make sure that you give the correct dose for the age of your child.
If you forget to take a dose, do not worry, just take the next dose when it is due. Do not take two doses together to make up for a forgotten dose.
Få ut det mesta av din behandling
Tillbaka till innehållLactulose can take up to 48 hours to act, so it may take two or three days before you feel the full benefit. However, if after several days you do not feel your symptoms are improving, or if they get worse, you should speak with a doctor for further medical advice.
It is important for you to drink plenty while you are constipated. Adults should aim to drink at least two litres (about 8-10 cups) of fluid per day. Most sorts of drink will do, but as a start, try just drinking a glass of water 3-4 times a day in addition to what you normally drink.
Try to eat a balanced diet containing high-fibre foods such as wholemeal and wholegrain breads and cereals, fruit and vegetables, brown rice and wholemeal pasta. If you are not used to a high-fibre diet, it may be best to increase the amount of fibre you eat gradually.
Keeping your body active will help you to keep your digestive system moving, so try to take some regular daily exercise.
You may wish to include some foods in your diet that contain sorbitol. Sorbitol is a naturally occurring sugar. It is not digested very well and draws water into your bowel which has an effect of softening stools. Fruits (and their juices) that have a high sorbitol content include apples, apricots, gooseberries, grapes (and raisins), peaches, pears, plums, prunes, raspberries and strawberries.
You can read more about how to prevent or treat constipation in the separate health information leaflets called Förstoppning (for adults) and Förstoppning hos barn.
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Can lactulose cause problems?
Tillbaka till innehållAlong with their useful effects, most medicines can cause unwanted side-effects although not everyone experiences them. The table below contains some of the ones which can occur with lactulose. You will find a full list in the manufacturer's information leaflet supplied with your medicine. Speak with your doctor or pharmacist if any of the following continue or become troublesome.
Lactulose side-effects | Vad kan jag göra om jag upplever detta? |
Excess wind (flatulence), tummy (abdominal) discomfort or cramps | These effects soon settle down as your body adjusts but if they continue or become troublesome, speak with your doctor or pharmacist for further advice |
Feeling sick (nausea) or being sick (vomiting) | Try taking lactulose with meals, or mixing your dose with some water or fruit juice |
Om du upplever några andra symtom som du tror kan bero på medicinen, tala med din läkare eller apotekare för vidare råd.
How to store lactulose
Tillbaka till innehållKeep all medicines out of the sight and reach of children.
Förvara på en sval, torr plats, borta från direkt värme och ljus.
Viktig information om alla läkemedel
Tillbaka till innehållViktig information om alla läkemedel
Om du köper några mediciner, kontrollera med en apotekare att de är säkra att ta tillsammans med dina andra mediciner.
Ta aldrig mer än den föreskrivna dosen. Om du misstänker att du eller någon annan kan ha tagit en överdos av denna medicin, gå till akutmottagningen på ditt lokala sjukhus. Ta med behållaren, även om den är tom.
Om du ska genomgå en operation eller tandbehandling, informera den som utför behandlingen om vilka mediciner du tar.
Denna medicin är för dig. Ge den aldrig till andra människor även om deras tillstånd verkar vara detsamma som ditt.
Do not keep out-of-date or unwanted medicines. Take them to your local pharmacy who will dispose of them for you.
Om du har några frågor om denna medicin, fråga din apotekare.
Rapportera biverkningar av ett läkemedel eller vaccin
Om du upplever biverkningar kan du rapportera dem online via Yellow Card website.

Osäker på att blanda mediciner?
Kontrollera möjliga interaktioner mellan läkemedel, kosttillskott och livsmedel innan du tar dem tillsammans.
Vidare läsning och referenser
- Manufacturer's PIL, Duphalac 3.335 g/5 ml Oral Solution; Mylan Products Ltd, The electronic Medicines Compendium. Dated April 2022.
- Mediciner Komplett BNF 89:e Utgåvan; Brittiska Läkarföreningen och Kungliga Farmaceutiska Sällskapet i Storbritannien, London.
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Artikelhistorik
Informationen på denna sida är skriven och granskad av kvalificerade kliniker.
Nästa granskning: 15 okt 2026
16 okt 2023 | Senaste versionen

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