Drug & supplement interaction

Calcium + Ofloxacin

Ofloxacin brand names: Oflox, Floxin, Floxin Injection, Floxin Otic.

Moderate Interaction
Medically reviewed by · Updated September 2026
The bottom line Moderate

Calcium has a moderate interaction with Ofloxacin. Calcium seems to reduce the absorption of quinolone antibiotics.

Read the full interaction report
SeverityModerate
LikelihoodProbable
EvidenceB
What do Severity, Likelihood & Evidence mean?
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Interaction report

Calcium and Ofloxacin

Here is the interaction we found between these two, with the evidence behind it.

Moderate

QUINOLONE ANTIBIOTICS

Why this applies to Ofloxacin

Ofloxacin falls under QUINOLONE ANTIBIOTICS — the group Calcium interacts with.

Calcium seems to reduce the absorption of quinolone antibiotics.
Advise patients to take oral quinolones at least 2 hours before or 4-6 hours after calcium supplements or calcium-fortified foods. Taking calcium at the same time as oral quinolones can reduce quinolone absorption. Calcium binds to quinolones in the gut.
Severity Moderate Likelihood Probable Evidence B

Interaction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports..

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's the thing to know if you take a calcium supplement and get prescribed ofloxacin: the calcium can grab onto the antibiotic right in your stomach and gut, forming a clump your body can't absorb well. The result is that less ofloxacin actually makes it into your bloodstream, which means it may not fight your infection as effectively. This isn't about side effects, it's about the antibiotic simply not working as well, and that can lead to a stubborn infection or treatment failure.

The good news is the fix is easy and well supported. Just space them out. A common approach is to take ofloxacin at least 2 hours before or 4 to 6 hours after your calcium, including calcium-fortified foods, antacids, and dairy. Same idea applies. If you're unsure how to time things around your doses, your pharmacist can map out a simple schedule with you.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Murry JJ, Healy MD. Drug-mineral interactions: a new responsibility for the hospital dietician. J Am Diet Assoc 1991;91:66-73.
  2. Pletz MW, Petzold P, Allen A, et al. Effect of calcium carbonate on bioavailability of orally administered gemifloxacin. Antimicrob Agents Chemother 2003;47:2158-60.. PubMed
  3. Kays MB, Overholser BR, Mueller BA, et al. Effects of sevelamer hydrochloride and calcium acetate on the oral bioavailability of ciprofloxacin. Am J Kidney Dis. 2003;42(6):1253-9. PubMed
  4. Neuhofel, A. L., Wilton, J. H., Victory, J. M., Hejmanowsk, L. G., and Amsden, G. W. Lack of bioequivalence of ciprofloxacin when administered with calcium-fortified orange juice: a new twist on an old interaction. J Clin Pharmacol. 2002;42(4):461-466. DOI

What These Ratings Mean

Every interaction above is graded three ways — here’s the key to each label.

Severity how clinically significant the interaction is
Major

Clinically significant. Avoid the combination, or use only under close professional supervision.

Moderate

Usually worth avoiding or managing — may need monitoring, a dose change, or timing apart.

Minor

Generally not serious. Be aware of it and mention it to your pharmacist.

Likelihood how strong the evidence is that the interaction actually happens in people
  • LikelyWell-controlled human studies have demonstrated the likely existence of this interaction.
  • ProbableInteraction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports.
  • PossibleInteraction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.
  • UnlikelyInteraction has been demonstrated in animal or in lab research but has been shown not to occur in humans.
Evidence the quality of the studies behind the rating (graded A–D)
  • AHigh-quality meta-analysis (quantitative systematic review).
  • BCase-control study.
  • CConsensus.
  • DAnecdotal evidence.

These ratings are for information only. Never start, stop, or otherwise change your therapy before speaking with your provider.

Keep it in perspective

Calcium Also Interacts With Other Medications

Calcium has 7 major, 142 moderate, 18 minor known drug interactions in our database — the Ofloxacin one above is one of them. If you take anything else, check it against the full list below.

Major 7 Moderate 142 Minor 18 No known interaction 2,663 (incl. Ofloxacin)
Taking anything else?

Check Another of Your Medications Against Calcium

Covers the 2,830 medications we’ve checked against Calcium. Pick one to open its full report.

From our Q&A

Questions About Calcium or Ofloxacin

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Calcium or Ofloxacin, not necessarily both, but if one is close to what you were about to ask it will usually go further than a database entry can:

Not quite your question? Ask our pharmacists directly — it is free, there is no account required, and answers usually come back within 24 hours.

Everything else you take

See Every Supplement That Interacts With Ofloxacin

This page covers Calcium only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Ofloxacin page lists 145 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Apple (major), Asarabacca (major), Beer (major) and Grapefruit (major).

By severity: 8 major · 115 moderate · 22 minor.

Open the Ofloxacin interaction page

One more smart check

Taking Calcium as Part of a Dietary Supplement Product? Check It for Interactions

We hold 38,397 real supplement products containing Calcium, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Calcium. Your product may carry other ingredients that interact with Ofloxacin too, on top of Calcium — and those would not show on this page. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Calcium and Ofloxacin Sit Against Everything Else

Out of every supplement and medication people look up on HelloPharmacist, here is where these two land this week — and which way each has been moving.

Supplement Calcium
Top 10

#2 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Ofloxacin
Steady interest

#1,583 of 2,830 medications looked up here in the last 7 days

29 days ago today

Position among everything looked up on this site, not a measure of how commonly either one is used or how important it is. A supplement can climb this list because of a news story. It counts every request to the page, automated ones included, and nothing here identifies anyone.

Supplement

About Calcium

What is Calcium?

  • Bone health and osteoporosis prevention
  • Dietary calcium deficiency
  • Heartburn relief (calcium carbonate antacids)
  • Supporting healthy teeth
  • High blood pressure support during pregnancy

Calcium is an essential mineral your body needs for strong bones, nerve signaling, and muscle function, and supplements can help fill gaps when diet falls short. Most people do best getting calcium from food, and supplements should be used at the lowest dose needed. Talk to your pharmacist or doctor before starting, especially if you have kidney problems or take other medicines.

Read the full Calcium monograph & all interactions
Medication

About Ofloxacin

What Is Ofloxacin Used For?

Brand names: Oflox, Floxin, Floxin Injection, Floxin Otic

Ofloxacin is used in several different forms, each approved for specific infections. The otic (ear) solution treats outer ear infections (otitis externa) in patients 6 months and older, chronic middle ear infections with a ruptured eardrum (chronic suppurative otitis media) in patients 12 and older, and acute middle ear infections in children 1 year and older who have ear tubes. The ophthalmic (eye) solution — including the brand Ocuflox — treats bacterial conjunctivitis (pink eye) and bacterial corneal ulcers.

Ofloxacin oral tablets treat adults with mild to moderate bacterial infections including community-acquired pneumonia, skin and skin structure infections, gonorrhea, chlamydial infections of the urethra or cervix, mixed urethral/cervical infections, and acute pelvic inflammatory disease. The oral tablet is also used for acute bacterial exacerbations of chronic bronchitis and uncomplicated cystitis, but only when no other treatment options are available, due to serious risk concerns with this drug class.

See full Ofloxacin drug information
Keep checking

Other Drugs & Calcium

Browse every other medication we’ve checked against Calcium — both the ones with a known interaction and the ones without. Select any drug for the full detail.

7Major
142Moderate
18Minor
2,662No known interaction
7 Major 142 Moderate 18 Minor 2,662 No interaction
Major

7 interactions

Moderate

142 interactions

Showing 60 of 142 moderate interactions — see all 142 on the Calcium page.

Minor

18 interactions

No interaction 2,662 drugs checked — show the list

We also checked Calcium against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 2,662 medications checked with no known interaction — see the full Calcium list.

See the full Calcium interactions page
See every supplement checked against Ofloxacin, ranked by severity
Sources

Sources & How We Checked

Interaction details are evidence-graded and sourced from the Natural Medicines database. The medication overview comes from MedlinePlus.

Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.

Parts of this content are provided by the Therapeutic Research Center, LLC.

DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.

© 2021 Therapeutic Research Center, LLC

Keep exploring
Calcium monograph › Uses, safety, and every drug interaction in one place Ofloxacin supplement interactions › Every supplement checked against Ofloxacin, ranked by severity Ofloxacin drug information › The full plain-English guide to this medication Supplement interaction checker › Check any supplement or product against your medications Browse medications A–Z › Every drug we've checked against herbs & supplements Ask a pharmacist › Free, personal answer from our licensed team
Pharmacist Counseling Corner

Taking Calcium and Ofloxacin Together: Common Questions

Can you take Calcium with Ofloxacin?
There is a moderate interaction, so it may be acceptable with monitoring or timing changes — but check with your pharmacist first. Read the full details on this page and confirm with your pharmacist before combining them.
How serious is the Calcium and Ofloxacin interaction?
We rate it Moderate. This combination may require monitoring, a dose adjustment, or separating the times you take each one. Consult your pharmacist before using them together.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

Still Have a Question About Ofloxacin and Calcium?

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This information is for education only and is not a substitute for professional medical advice. Always check with your pharmacist or doctor before starting, stopping, or combining supplements and medications.