Drug interactions
Doxycycline + Magnesium hydroxide
Severity: Moderate
Doxycycline and Magnesium hydroxide: 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 in antacids binds oral doxycycline in the gut, forming poorly absorbed chelates. This lowers doxycycline levels and may cause treatment failure, although the effect is smaller than with older tetracyclines.
What this interaction means in plain words
Doxycycline and Magnesium hydroxide 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.
Doxycycline belongs to Anti Bacterial; Magnesium hydroxide belongs to Gastrointestinal Tract.
Why it happens
Chelation of doxycycline by divalent magnesium cations in the gastrointestinal tract reduces absorption.
What to do
Take doxycycline at least 2 hours before or several hours after magnesium hydroxide. Consider avoiding regular antacid use during therapy.
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 Magnesium hydroxide
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 hydroxide?
MediHelp rates the interaction as moderate. Doxycycline and Magnesium hydroxide 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 in antacids binds oral doxycycline in the gut, forming poorly absorbed chelates. This lowers doxycycline levels and may cause treatment failure, although the effect is smaller than with older tetracyclines.
How serious is the interaction between Doxycycline and Magnesium hydroxide?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Take doxycycline at least 2 hours before or several hours after magnesium hydroxide. Consider avoiding regular antacid use during therapy.
What other medicines interact with Magnesium hydroxide?
MediHelp also lists interactions of Magnesium hydroxide with, for example, Ciprofloxacin, Dolutegravir, Gemifloxacin. The full list is on the Magnesium hydroxide page.
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