Constipation From Your Medicines? How Duphalac (Lactulose) Can Help

Many common medicines can cause constipation as a side effect, and it happens more often than people realise. ^1-3 If you have started a new medicine and notice you are going to the toilet less often, or that your stools have become hard and difficult to pass, your medication may be the reason. ¹ The good news is that this kind of constipation can usually be managed. This article explains which medicines are most likely to cause constipation, why it happens, and how a laxative such as Duphalac may help relieve it.

Can your medicines cause constipation?

Yes — Medicines are a known cause of constipation.^1-3 Constipation means having fewer bowel movements than usual, or passing stools that are hard, dry or difficult to move.²

Diet, fluids and how active you are all play a part. So do some medicines, which can slow the bowel down and lead to these symptoms.¹

It is more common than you might think. Medicine-related constipation is thought to account for around 11% of all treated constipation cases.³ However, as the medicine causing the constipation is often needed for another health condition, this type of constipation can be easy to overlook.³

Which medicines are most likely to cause it?

Several everyday types of medicine are linked with constipation. Opioid painkillers are a common cause, along with some medicines used for pain, high blood pressure, seizures, depression, nervous-system conditions and allergies.¹

A large review of reported side effects found that pain medicines such as opioids, some antidepressants, iron and certain other medications are among those associated with constipation.³ These findings show a link between some medicines and constipation and it does not mean that every medicine will affect every person, as responses vary from one person to another.³ If you think a medicine is affecting your bowels, it is worth discussing it with your doctor or pharmacist.

Why do some medicines make you constipated?

Some medicines slow down the way your bowel works. For example, opioid painkillers act on receptors in the gut, reducing the natural muscle movements that push stool along and increasing the time it spends in the bowel.⁴

That extra time is what causes the problem. When stool stays longer in the bowel, more water is drawn out of it, so it becomes harder and more difficult to pass.¹ This is why constipation is one of the most common side effects of opioid treatment.⁴

What can you try first?

Simple lifestyle steps are usually the first thing to try. Drinking plenty of fluids, eating a healthy diet, eating more fibre and staying physically active can all help keep your bowels moving.²

Just as importantly, do not stop a medicine your doctor has prescribed on your own because it is causing constipation — the best approach should be decided with your doctor or pharmacist.⁴

If these everyday measures are not enough, a pharmacist can suggest a suitable laxative.²

How does Duphalac (lactulose) work, and where does it fit?

Duphalac (lactulose) is an osmotic laxative that helps relieve constipation by drawing water into the bowel to soften stools.^5,6

Lactulose is broken down by the natural bacteria in your colon, and as it makes the colon more acidic, it draws water in. This increases the water content and the volume of the bowel contents, which helps stimulate the bowel to move.⁵ This can help restore the natural rhythm of the bowel.⁵

Lactulose is one of the options to consider when simple measures, such as fibre and other everyday steps, have not brought enough relief.⁷ It is worth knowing that the clinical evidence for lactulose in long-term constipation is limited.⁷

Lactulose may not provide an instant remedy, and it may take a couple of days before you see an effect.^5,6 If your constipation has not improved after 4 or 5 days, speak to your doctor.⁶ It is important to drink plenty of water/liquids to support your bowel movements.⁵

Is Duphalac right for you if you take other medicines?

If you take other medicines, it is important to get advice before using lactulose. Tell your doctor or pharmacist about all the prescription and non-prescription medicines you take, so they can check whether it is suitable for you.⁸

Lactulose can be used during pregnancy and while breastfeeding as very little of it is absorbed into the body.⁵

Lactulose contains a synthetic sugar but the amounts (recommended doses) used for constipation are not usually a problem for people with diabetes.^5,8 As it is poorly absorbed, it doesn’t affect blood sugar levels in the same way as other sugars.⁵ Higher doses of lactulose are used for some conditions, and that is when it may need to be taken into account.⁵ It is still sensible to check with a healthcare professional before taking.^5,8

Lactulose is not suitable for everyone — for example, people with galactosaemia (a rare sugar disorder) or a bowel blockage should not take it, and those who are intolerant to lactose should use it with care.⁵

Important safety information

Like all medicines, lactulose can cause side effects, although many people have none or only mild ones.⁹

The most common side effects are wind (flatulence) and bloating.⁹ Wind may occur in the first few days and usually settles on its own.⁵ Higher doses than instructed can lead to diarrhoea and stomach pain; if this happens, the amount taken can be reduced.⁵ It is recommended to drink plenty of fluids while taking lactulose.^5,10

This is not a full list of side effects — always read the patient leaflet and speak to a pharmacist or doctor if you have questions.⁹

When should you speak to a doctor or pharmacist?

Speak to a healthcare professional if your constipation does not improve or if you are worried.

See your doctor or pharmacist if your symptoms do not get better after a few days, or if you have painful tummy symptoms you cannot explain.^5,6 Also speak to your doctor if you notice warning signs such as bleeding, unexplained weight loss, or a lasting change in your bowel habits.¹

Conclusion

Constipation caused by medicines is common, but it can usually be managed.¹

The first step would be making sure you are getting enough fluids, fibre and physical activity, and getting advice from a health professional on any prescribed medicines you may be taking which may be a factor in your constipation.^2,4

When more help is needed, an osmotic laxative such as Duphalac (lactulose) can help relieve constipation by softening stools.^5,6

Your pharmacist or doctor can help you decide whether it is right for you.

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This article was written with the assistance of generative AI technology and reviewed for accuracy.