Can I take Aspirin and Carbonate together?
Drug interaction guide
Originally published 14 Mar 2026
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Taking carbonates (like calcium carbonate antacids) at the same time as aspirin can make the aspirin less effective. It may also increase how quickly aspirin is removed from your body by your kidneys.
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Why this happens
Carbonates are alkaline (antacids) and raise the pH level in your stomach and urine. In the stomach, this can cause some types of aspirin (especially enteric-coated ones) to dissolve too early. In the kidneys, less acidic urine causes aspirin to be cleared out of your system faster, lowering the amount of medicine in your blood.
What you should do
Back to contentsTo make sure your aspirin works properly, try to space the doses apart. Take your aspirin at least 2 hours before or 2 hours after taking any carbonate-based antacids or supplements.
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Important precautions
Back to contentsAsthma
Do not take this medicine if you have a history of asthma triggered by aspirin or other non-steroidal anti-inflammatory drugs (NSAIDs), as it can cause a life-threatening asthma attack.
Children under 16 years old
Never give aspirin to children under 16 unless specifically prescribed by a doctor. It can cause Reye’s syndrome, a rare but very serious condition that causes swelling in the liver and brain.
Pregnancy (third trimester)
Do not take aspirin during the last 3 months of pregnancy as it can cause serious heart or kidney problems in the unborn baby and increase the risk of bleeding during delivery.
Food and drink warnings
Back to contentsAlcohol
Drinking alcohol while taking aspirin can increase the risk of stomach irritation and bleeding. It is best to limit alcohol consumption or avoid it if you have a history of stomach ulcers.
Dairy products
While calcium carbonate is often used as a supplement, consuming very high amounts of dairy (milk, cheese, yoghurt) alongside calcium carbonate supplements can occasionally lead to 'milk-alkali syndrome', which causes high calcium levels in the blood.
Caffeine
Large amounts of caffeine (found in coffee, tea, and some fizzy drinks) can slightly reduce how much calcium your body absorbs from calcium carbonate.
Iron-rich foods or Spinach/Rhubarb
Calcium carbonate can prevent your body from absorbing iron from your food. Additionally, foods high in oxalates (like spinach and rhubarb) can reduce the absorption of calcium. It is best to take calcium carbonate at a different time of day from iron-rich meals.
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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.
14 Mar 2026 | Originally published

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