The short answer
Taking oral iron at the same time as ofloxacin can reduce antibiotic absorption. In a small ferrous-sulfate study, total ofloxacin exposure fell by 25% and its peak by 36%. Current tablet directions advise at least 2 hours between ofloxacin and iron in either direction.
What this answer covers
Oral ofloxacin tablets and oral iron products; direct study tested ferrous sulfate. Intravenous iron and nonoral antibiotic use are outside this gut-absorption finding.
- Supplement or preparation
- Iron
- Medication ingredient
- ofloxacin
How much did ferrous sulfate change absorption?
Eight healthy volunteers received ofloxacin 400 mg with and without ferrous sulfate providing 100 mg elemental iron. When taken together, the antibiotic’s overall blood exposure was 25% lower and its peak was 36% lower. These are pharmacokinetic measurements, not a prediction that one quarter of infections will fail treatment. The experiment did not compare all iron salts.
How should the tablets be separated?
The current ofloxacin label requires at least 2 hours before or after the iron-containing product. That timing comes from product guidance, while the direct iron experiment tested simultaneous administration. If iron is taken more than once daily, a pharmacist can arrange the schedule around the prescribed antibiotic rather than having you miss or add doses.
Are other minerals interchangeable with iron?
No. The same paper studied several different antibiotics, and ofloxacin was less affected than ciprofloxacin or norfloxacin. A separate ofloxacin antacid trial also found little effect with separated calcium carbonate. Neither larger percentages from another drug nor a general mineral warning should replace the result for the exact medicine and preparation you use.
What if iron is in a multivitamin?
Include the iron in prenatal vitamins or other combined supplements when reviewing the schedule. Keep the elemental iron amount and salt name available, because a product’s marketing name may not reveal all relevant ingredients. A dosing interaction does not remove the reason iron was prescribed; coordinate both treatments and seek advice if doses have overlapped.
Evidence and practical considerations
Absorption & effectiveness
Taking oral iron at the same time as ofloxacin can reduce antibiotic absorption. In a small ferrous-sulfate study, total ofloxacin exposure fell by 25% and its peak by 36%. Current tablet directions advise at least 2 hours between ofloxacin and iron in either direction.
- Exact scope
- oral iron preparations, directly tested as ferrous sulfate providing 100 mg elemental iron with oral racemic ofloxacin tablets
- Medication form and route
- oral
- Timing or duration
- Single concurrent antibiotic and iron dose in healthy volunteers; ongoing scheduling precaution while both oral treatments are used.
What remains uncertain
- Eight participants, one iron salt, no infection outcomes and no iron-spacing trial. Other minerals in grouped claims are not assumed to share the same effect size; calcium evidence is qualified.
Factors that may matter: exact salt and dose; order and interval between oral doses; combination-product ingredients; oral versus nonoral route.
Read the supporting source summaries
Source 1: regulatory product label
dailymed.nlm.nih.gov · Source check Sep 10, 2026
Population: Patients prescribed oral ofloxacin tablets.
Product directions require at least 2 hours before or after named mineral products. Ofloxacin can be taken without regard to meals.
How this applies: Exact parent RxCUI 7623, oral racemic ofloxacin. Levofloxacin enantiomer data, ophthalmic products and injections are not substituted. Article-specific counterparty: oral iron preparations, directly tested as ferrous sulfate providing 100 mg elemental iron.
Some explanatory wording describes quinolones as a class, but the dosing direction explicitly names ofloxacin. Effect sizes and every supplement salt are not quantified.
Source 2: original human clinical study
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: Eight healthy volunteers in the ofloxacin arm of three separate two-period crossover trials.
Concurrent iron reduced ofloxacin AUC by 25% and peak concentration by 36%. Authors advised avoiding simultaneous use, especially for only moderately susceptible organisms.
How this applies: Uses only the ofloxacin arm, not the much larger ciprofloxacin/norfloxacin effects in the same paper. Article-specific counterparty: oral iron preparations, directly tested as ferrous sulfate providing 100 mg elemental iron.
Small single-dose experiment with ferrous sulfate; no quantified treatment failure or directly tested spacing interval. Full clinical article was not inspected; original author abstract was read.
Source 3: original human clinical study
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: 32 healthy participants in a randomized open-label crossover trial; 16 in each antacid group.
Calcium carbonate had no significant effect at the tested intervals. Magnesium/aluminum antacid 2 hours before produced a small significant reduction in overall exposure and peak. Authors judged effects generally not clinically important with at least 2 hours separation.
How this applies: Direct for the two specified antacids and oral ofloxacin at tested separated intervals. Calcium result cannot clear simultaneous use or every calcium salt. Article-specific counterparty: oral iron preparations, directly tested as ferrous sulfate providing 100 mg elemental iron.
Simultaneous administration was not tested. Combined Mg/Al cannot isolate either mineral. Healthy-volunteer pharmacokinetics, not infection outcomes. Full clinical article was not inspected; original author abstract was read.
Research assessment: · Open full citations ↗
Review and change history
- Publication status
- Published research summary
- Clinical review
- Not yet recorded
| Date | Update |
|---|---|
| Article prepared | |
| Exact-drug product guidance and original research checked; complete private article prepared with evidence limitations and current-claim adjudication. | |
| Research summary published |
Article revision: 8accf9b20bf2d008
This guide brings together the evidence records used by our interaction checker. Each finding retains its own preparation limits, research date, and source summaries.
Full citations require verification. Reading this answer and the source summaries does not.
Taking other supplements or medications?
Use the checker to explore your other combinations. Ask a pharmacist to review the exact products, amounts and medical conditions in your complete list.
Open the interaction checkerInformation, not medical advice. Do not change prescribed treatment based on this guide.