Doxycycline × Iron oral (salts: sulfate, bisglycinate, fumarate, gluconate, polymaltose; heme iron polypeptide, lactoferrin)
MajorTetracyclines×Oral iron preparations; antianaemic agents
Updated · Methodology
Mechanism
Iron is named in the label alongside calcium and magnesium as a cation that reduces tetracycline absorption. The binding works both ways: the iron that gets absorbed also drops, so neither the antibiotic nor the anaemia treatment performs as planned.
Symptoms
An antibiotic course without the expected response and, in parallel, ferritin that fails to rise at the 4–8 week check.
Management
At least 2–3 hours apart. For short courses the practical arrangement is iron with dinner and doxycycline in the morning. If the course is long, repeat ferritin at the end to confirm the iron treatment is making progress.
Check the full regimen, not just this pair
Opens the checker with these two drugs prefilled. Add the rest of the regimen and recompute additive risks.
Summary of a multi-drug list →
Medicine list: everything you take in one place →
Sources
- FDA: Doxycycline hyclate tablet (Alembic Pharmaceuticals Inc.) – Prescribing Information (2014)– ; DailyMed setid cff08863-7156-49d0-abbd-8f9274302886
- AEMPS: Ficha técnica Doxiciclina Normon 100 mg comprimidos recubiertos (2024)– AEMPS, CIMA, nº registro 47077, sección 4.5
- NIH Office of Dietary Supplements: Iron – Health Professional Fact Sheet (2025)– NIH ODS, Iron, Interactions with Medications