Drug interactions
Doxycycline + Magnesium supplement
Severity: Moderate
Doxycycline and Magnesium supplement: moderate interaction.
Last updated
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Magnesium given by mouth binds oral doxycycline in the gut and forms poorly absorbed chelates. This lowers doxycycline blood levels and may lead to treatment failure, particularly in serious infections.
What this interaction means in plain words
Doxycycline and Magnesium supplement can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Why it happens
Chelation of doxycycline by divalent magnesium cations in the gastrointestinal tract reduces its absorption.
What to do
Give doxycycline at least 2 hours before or 4 hours after the magnesium product. Choose a non-cation-containing alternative where separation is not feasible.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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Other interactions of Doxycycline
- Acitretin + Doxycycline Contraindicated
- Aminolevulinic acid + Doxycycline Major
- Cholera vaccine + Doxycycline Major
- Doxycycline + Isotretinoin Major
- Doxycycline + Methoxyflurane Major
- Doxycycline + Microbiota Major
Frequently asked questions
Can I take Doxycycline with Magnesium supplement?
MediHelp rates the interaction as moderate. Doxycycline and Magnesium supplement can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Magnesium given by mouth binds oral doxycycline in the gut and forms poorly absorbed chelates. This lowers doxycycline blood levels and may lead to treatment failure, particularly in serious infections.
How serious is the interaction between Doxycycline and Magnesium supplement?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Give doxycycline at least 2 hours before or 4 hours after the magnesium product. Choose a non-cation-containing alternative where separation is not feasible.
What other medicines interact with Doxycycline?
MediHelp also lists interactions of Doxycycline with, for example, Acitretin, Aminolevulinic acid, Cholera vaccine. The full list is on the Doxycycline page.
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