Drug interactions
Doxycycline + Magnesium sulphate
Severity: Moderate
Doxycycline and Magnesium sulphate: 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
Oral magnesium salts bind tetracyclines in the gut and reduce their absorption, which can lead to subtherapeutic antibiotic levels and treatment failure. The interaction is relevant only when both are given orally.
What this interaction means in plain words
Doxycycline and Magnesium sulphate 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 sulphate belongs to Cardiovascular.
Why it happens
Chelation of doxycycline by divalent magnesium cations in the gastrointestinal tract, forming poorly absorbed complexes.
What to do
Give doxycycline at least 2 hours before or several hours after oral magnesium. Intravenous magnesium does not need separation.
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 sulphate
- Amikacin + Magnesium sulphate Moderate
- Amphotericin b deoxycholate + Magnesium sulphate Moderate
- Atracurium + Magnesium sulphate Moderate
- Baloxavir marboxil + Magnesium sulphate Moderate
- Ciprofloxacin + Magnesium sulphate Moderate
- Cisatracurium + Magnesium sulphate Moderate
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 sulphate?
MediHelp rates the interaction as moderate. Doxycycline and Magnesium sulphate 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. Oral magnesium salts bind tetracyclines in the gut and reduce their absorption, which can lead to subtherapeutic antibiotic levels and treatment failure. The interaction is relevant only when both are given orally.
How serious is the interaction between Doxycycline and Magnesium sulphate?
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 several hours after oral magnesium. Intravenous magnesium does not need separation.
What other medicines interact with Magnesium sulphate?
MediHelp also lists interactions of Magnesium sulphate with, for example, Amikacin, Amphotericin b deoxycholate, Atracurium. The full list is on the Magnesium sulphate page.
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