Can I take Amitriptyline and Lactulose together?
Drug interaction guide
Originally published 25 Jan 2026
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Amitriptyline can cause constipation as a side effect. This may make lactulose (a laxative) less effective or mean you need a higher dose to see results.
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Why this happens
Amitriptyline has 'anticholinergic' effects, which slow down the movement of the digestive system. Lactulose works by drawing water into the bowel to encourage movement. These two medications essentially work against each other regarding bowel habits.
What you should do
It is safe to take these together, but be aware that the amitriptyline might be the cause of your constipation. If your constipation does not improve with lactulose, speak to your doctor or pharmacist about adjusting your dose or trying a different type of laxative.
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Using other medicines
Taking multiple medicines? Our Medicines Interaction Checker helps you check whether your prescriptions, over-the-counter medicines, and supplements are safe to take together. Simply search for your medicines to see potential interactions and what to do about them.
Disclaimer
This information is for general educational purposes only and should not be relied upon as a substitute for professional medical advice. Always consult your GP, pharmacist, or another qualified healthcare professional before making decisions about your medications. Individual circumstances may vary, and only a healthcare professional who knows your medical history can provide personalised guidance.
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Article history
The information on this page is written and peer reviewed by qualified clinicians.
25 Jan 2026 | Originally published

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