Can I take Lactulose and Naproxen together?
Drug interaction guide
Originally published 25 Jan 2026
Meets Patient’s editorial guidelines
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There is no known direct interaction between lactulose and naproxen. It is generally safe to take these two medicines together.
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Why this happens
Lactulose is a sugar-based laxative that works locally in the bowel to soften stools. Naproxen is a non-steroidal anti-inflammatory drug (NSAID) used for pain and inflammation. They are processed by the body through different pathways and do not interfere with how the other works.
What you should do
Back to contentsYou can take both medicines as prescribed. However, always ensure you drink plenty of water while taking lactulose to help it work effectively and to prevent dehydration, which can sometimes increase the risk of kidney strain when taking NSAIDs like naproxen.
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Important precautions
Back to contentsAsthma
Do not take naproxen if you have asthma that is sensitive to aspirin or other non-steroidal anti-inflammatory drugs (NSAIDs), as it can trigger a severe or life-threatening asthma attack.
Stomach ulcers or bleeding
Naproxen significantly increases the risk of stomach ulcers and internal bleeding. Avoid it if you have a history of stomach ulcers or inflammatory bowel disease.
Pregnancy (third trimester)
Do not take naproxen if you are more than 20 weeks pregnant. It can cause serious heart or kidney problems in the unborn baby and lead to complications during delivery.
Galactosaemia
You must not take lactulose if you have galactosaemia, a rare genetic disorder where your body cannot process galactose.
Diabetes
If you are taking high doses of lactulose for liver disease (portal systemic encephalopathy), the sugar content may affect your blood glucose levels.
Food and drink warnings
Back to contentsAlcohol
It is best to avoid or strictly limit alcohol while taking naproxen. Both alcohol and naproxen can irritate the lining of your stomach; combining them significantly increases your risk of stomach ulcers and internal bleeding.
It is best to avoid or strictly limit alcohol when taking lactulose. Alcohol can cause dehydration, which may worsen the constipation you are trying to treat. Additionally, if you are taking lactulose for liver disease (hepatic encephalopathy), alcohol must be avoided entirely as it can significantly worsen your condition.
Water and Fluids
It is essential to drink plenty of fluids (such as water) while taking lactulose. This medicine works by drawing water into the bowel to soften stools; if you do not drink enough, the medicine may not work effectively and you may become dehydrated.
Food (General)
You should always take naproxen with or just after a meal or a snack. This helps to protect your stomach lining and reduces the risk of indigestion and stomach pain.
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Using other medicines
Back to contentsTaking 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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