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Can I take Aspirin and Diclofenac together?

Drug interaction guide

Taking aspirin and diclofenac together significantly increases your risk of developing stomach ulcers, internal bleeding, and kidney problems. Both medicines belong to the same family (NSAIDs), and using them together 'doubles up' the risk of side effects without providing much extra pain relief.

You should not take aspirin and diclofenac together unless specifically instructed by your doctor.

Both drugs work by blocking enzymes (COX-1 and COX-2) that protect the lining of your stomach and keep your kidneys working properly.

When you take both, the protective layer in your stomach is weakened further, and blood flow to the kidneys can be reduced. Additionally, both drugs thin the blood, making any bleeding more difficult to stop.

If you must take both, your doctor may prescribe a 'stomach protector' medicine (such as omeprazole).

If you are taking low-dose aspirin for heart protection, speak to your GP or pharmacist before using diclofenac, as diclofenac can interfere with aspirin's heart-protective benefits and increase your risk of a stomach bleed.

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How to know if you're having a drug interaction?

You may be experiencing an interaction between aspirin and diclofenac if you have:

  • Stomach pain, indigestion, or heartburn.

  • Nausea or vomiting.

  • Black, tarry stools or blood in your stools.

  • Vomiting blood.

  • Unusual bruising or bleeding.

  • Dizziness or headaches.

  • Swelling of the ankles or feet.

  • Shortness of breath or chest pain (rare but serious).

If you have any of the above symptoms, you should:

  • Stop taking the medicines and contact your GP or pharmacist if you develop stomach pain, indigestion, nausea, unusual bruising or mild bleeding.

  • Seek urgent medical help (call 999 / go to A&E) if you have:

    • Black, tarry poo.

    • Vomit (sick) that looks like blood or coffee grounds.

    • Severe stomach pain.

    • Chest pain or shortness of breath.

    • Signs of an allergic reaction (swelling of face/lips, difficulty breathing).

Do not restart either medicine until you have spoken to a healthcare professional.

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Asthma

Do not take these medicines if you have asthma and have ever had a flare-up or breathing difficulties triggered by aspirin or other NSAIDs. This can cause a life-threatening allergic reaction or severe asthma attack.

Stomach ulcers or bleeding

Avoid these medicines if you have a history of stomach ulcers or gastrointestinal bleeding. They significantly increase the risk of serious stomach damage and internal bleeding.

Pregnancy (third trimester)

Do not take these medicines if you are more than 20 weeks pregnant. They can cause serious kidney or heart problems in the unborn baby and may lead to complications during delivery.

Alcohol

Drinking alcohol while taking these medicines increases the risk of irritation and bleeding in your stomach and intestines. It is best to avoid or limit alcohol consumption.

Caffeine (coffee, tea, energy drinks)

Aspirin can increase the effects of caffeine, potentially leading to jitteriness, a racing heart, or difficulty sleeping. Additionally, both caffeine and aspirin can irritate the stomach lining, increasing the risk of indigestion or ulcers when combined.

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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.

Article history

The information on this page is written and peer reviewed by qualified clinicians.

  • 25 Jan 2026 | Originally published
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