Lactulose: What is it? Precautions, Administration and Recommendations

It is a laxative that can take up to 48 hours to have an effect.

If you find that the medicine makes you feel dizzy, mix your dose with a little water or fruit juice. Alternatively, take your doses with a meal.

Eating a healthy diet, drinking plenty of water and exercising regularly, can help prevent constipation.

The constipation is a common problem

It may mean going to the bathroom less often than usual to empty the bowels or pass hard or painful stools. Constipation can be caused by several things.

Not eating enough fiber or not drinking enough liquid can cause constipation. Some conditions (such as pregnancy) can cause constipation, as well as lack of exercise or movement (such as being sick in bed) and some medications.

Often, increasing the amount of fiber in your diet (such as eating more fruits, vegetables, cereals and whole grain bread) and drinking lots of water every day can prevent or relieve constipation.

You will have been recommended lactulose, a laxative, to help relieve constipation if you can not increase fiber in your diet or if this is insufficient.

Lactulose works by drawing fluid into the intestine, which makes your stools softer and easier to pass. It is available by prescription, and can also be purchased without a prescription in pharmacies.

Lactulose also changes the acidity of the stool and this helps to discourage the growth of some germs (bacteria) present in the intestine.

Because of this, lactulose is also prescribed for people with a liver problem called hepatic encephalopathy . If it has been prescribed for this reason, ask your doctor if you need more information about the medication.


Some medications are not suitable for people with certain conditions, and sometimes a medication can only be used if additional 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 can not digest the milk sugar (lactose intolerant).
  • If you have a condition called galactosemia, where your body can not process galactose .
  • If you are pregnant or breast-feeding. It is not known that lactulose is harmful to a baby, but while waiting or feeding a baby, you should only take medication on the recommendation of a doctor.
  • If it is intended for a child, laxatives should only be administered to children following the advice of a doctor or health professional.
  • If you are taking other medications, including those available to buy without a prescription, as well as herbal and complementary medications.
  • If you have ever had an allergic reaction to this or any other medication.


Before starting treatment, read the printed information brochure from the package manufacturer. It will give you more information about lactulose and will provide you with a complete list of the side effects you may experience.

Take lactulose exactly as your doctor tells you to, or as directed on the package. The usual dose for constipation in an adult is 15 ml (three tablespoons of 5 ml) twice a day, although the recommended dose may be different, as it will be adjusted according to your needs.

If a doctor or health care professional has recommended lactulose your child, carefully check the package label to make sure you give the correct dose for your child’s age.

If you forget to take a dose, do not worry, just take the next dose when it’s time. Do not take two doses together to make up for a forgotten dose.


Lactulose can take up to 48 hours to act, so it can take two or three days before you feel the full benefit. However, if after several days you do not feel that your symptoms are getting better, or if they get worse, you should talk to a doctor to get more information.

It is important that you drink a lot of liquid while you are constipated. Adults should try to drink at least two liters (about 8-10 cups) of fluid per day. Most types of drinks will work, but as a start, try simply drinking a glass of water 3-4 times a day in addition to what you normally drink.

Try eating a balanced diet that contains foods high in fiber, such as whole grain breads and cereals, fruits and vegetables, brown rice and whole grain pasta. If you are not used to a high fiber diet, it may be better to gradually increase the amount of fiber you consume.

Keeping your body active will help keep your digestive system moving, so you should perform some daily exercises.

You may want to include some foods in your diet that contain sorbitol. Sorbitol is a natural sugar. It does not digest very well and attracts water to the intestine, which has a softening effect on the stool.

Fruits (and their juices) that are high in sorbitol include apples, apricots, currants, grapes (and raisins), peaches, pears, plums, prunes, raspberries and strawberries.

Foods such as cakes, desserts, sweets, cheese and cake can make constipation worse and it is better to avoid it.

Important information on all medicines

  • If you buy any medication, consult a pharmacist who is safe to take it with your other medications.
  • This medicine is for you. Never give it to other people, even if their condition seems to be the same as yours.
  • If you have any questions about this medication, ask your pharmacist.