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Can I take 1.25 and Vitamin a together?

Drug interaction guide

Taking 1.25 (calcitriol) and Vitamin A together can lead to dangerously high levels of calcium in your blood. This can cause symptoms like nausea, vomiting, constipation, and in severe cases, damage to your kidneys or heart. Additionally, high doses of Vitamin A can interfere with how calcitriol works, potentially making your treatment less effective or more toxic.

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Why this happens

Calcitriol (1.25-dihydroxyvitamin D3) is a very potent form of Vitamin D that helps your body absorb calcium. Vitamin A also influences bone metabolism and calcium levels. When taken together, they can have an 'additive' effect, pushing calcium levels too high. Furthermore, Vitamin A can compete with Vitamin D at a cellular level, disrupting the balance of how your body uses these nutrients.

You should speak to your doctor or pharmacist before taking Vitamin A supplements if you are prescribed calcitriol (1.25). Your doctor may need to monitor your blood calcium levels more frequently or adjust your doses. Avoid taking over-the-counter multivitamins containing Vitamin A without professional medical advice.

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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.

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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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