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Can I take Calcium and Doxycycline together?

Drug interaction guide

Taking calcium at the same time as doxycycline can stop the antibiotic from working properly. The calcium attaches to the medicine in your stomach, which prevents your body from absorbing it into your bloodstream. This means the infection you are treating might not clear up as it should.

Why this happens

This is an absorption issue called 'chelation'. Calcium binds to the doxycycline molecules in the digestive tract to form a large complex that the body cannot absorb.

You should separate the doses of these two substances. Take your doxycycline at least 2 hours before or 3 hours after consuming calcium-rich foods (like milk, cheese, or yoghurt) or calcium supplements.

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Photosensitivity

Doxycycline makes your skin much more sensitive to sunlight. You will burn more easily; avoid sunbeds and use high-factor sunscreen even on cloudy days.

Oesophageal irritation

To prevent painful throat irritation or ulcers, swallow doxycycline with a full glass of water while sitting or standing. Do not lie down for at least 30 minutes after taking it.

Alcohol

Chronic or heavy drinking can speed up the removal of doxycycline from your body, making the antibiotic less effective. It is best to avoid or limit alcohol during your treatment.

Caffeine (coffee, tea, cola)

High amounts of caffeine can slightly interfere with how your body absorbs calcium and may increase the amount of calcium lost in your urine. Try to limit caffeine intake or have it at a different time than your supplement.

High-fibre foods (bran, whole grains) and Spinach/Rhubarb

Foods very high in phytic acid (grains) or oxalic acid (spinach, rhubarb) can bind to calcium and reduce its absorption. Avoid taking your calcium supplement at the same time as a very high-fibre meal.

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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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