Drug interactions
Doxycycline + Warfarin
Severity: Moderate
Doxycycline and Warfarin: 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
Doxycycline may increase the anticoagulant effect of warfarin and raise INR, with a risk of bleeding. The effect varies between patients and is more likely with illness and reduced oral intake.
What this interaction means in plain words
Doxycycline and Warfarin 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; Warfarin belongs to Cardiovascular.
Why it happens
Probably reduced vitamin K-producing gut flora and possible effects on clotting factor synthesis; not fully established.
What to do
Check INR within a few days of starting or stopping doxycycline and adjust the warfarin dose as needed. Educate the patient on bleeding signs.
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
Other interactions of Warfarin
- Defibrotide + Warfarin Contraindicated
- Ketorolac + Warfarin Contraindicated
- Abciximab + Warfarin Major
- Acetylsalicylic acid + Warfarin Major
- Adagrasib + Warfarin Major
- Amiodarone + Warfarin Major
Frequently asked questions
Can I take Doxycycline with Warfarin?
MediHelp rates the interaction as moderate. Doxycycline and Warfarin 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 may increase the anticoagulant effect of warfarin and raise INR, with a risk of bleeding. The effect varies between patients and is more likely with illness and reduced oral intake.
How serious is the interaction between Doxycycline and Warfarin?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Check INR within a few days of starting or stopping doxycycline and adjust the warfarin dose as needed. Educate the patient on bleeding signs.
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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