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Doxycycline with antacid — GPhC CRA MCQ

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EasyGastrointestinal TherapeuticsDoxycycline with antacidGPhC CRA

A patient taking doxycycline for acne buys a magnesium-containing antacid and plans to take both after breakfast. What is the most appropriate action?

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Correct answer: DMagnesium antacids can reduce doxycycline absorption

Divalent and trivalent cations can bind tetracyclines and reduce absorption. In this scenario, the pharmacist should prioritise safe supply, appropriate counselling and timely referral or clarification where needed. This is the single best answer because the other options would either delay assessment, ignore a clinically significant risk, or create an unsafe legal or professional outcome.

Reference: BNF