NutriStack
Calcium and Ciprofloxacin, timing-sensitive.
Calcium chelates ciprofloxacin in the GI tract, forming insoluble calcium-quinolone complexes that can reduce ciprofloxacin absorption by up to 90%. This can render the antibiotic completely ineffective, leading to treatment failure and potential antibiotic resistance development.
One pair, every claim cited. The two substances, the type, the mechanism, the recommendation, and the primary literature.
Same shape as the other 1,729 pairs in the public database.
From the interaction database
What the row says.
Every entry follows the same shape: what is happening, the mechanism, the recommendation, and the primary literature.
At a glance
- Substances
- Calcium and Ciprofloxacin
- Pair type
- Timing Sensitive
- Evidence (highest tier)
- Strong
- Source citations
- 4 sources
- Stack Score effect
- −5 to your Stack Score (per scored timing-sensitive row).
- Scope
- Supplement × Prescription
- Last verified
- May 30, 2026
Timing Sensitive · Strong evidence
Timing Sensitive
What is happening. Calcium chelates ciprofloxacin in the GI tract, forming insoluble calcium-quinolone complexes that can reduce ciprofloxacin absorption by up to 90%. This can render the antibiotic completely ineffective, leading to treatment failure and potential antibiotic resistance development.
Mechanism. Calcium divalent cations form insoluble chelate complexes with ciprofloxacin's 4-oxo and 3-carboxyl groups, which are essential for both antibacterial activity and GI absorption. The chelated complex is not absorbed and is excreted in feces.
Recommendation. Separate ciprofloxacin and calcium supplements by at least 2 hours (take ciprofloxacin 2 hours before or 6 hours after calcium). This timing separation is critical for maintaining antibiotic efficacy.
Minimum separation. 120
Sources (4)
- Lomaestro BM, Bailie GR. Absorption interactions with fluoroquinolones. Drug Saf. 1995;12(5):314-333. PMID 7646824
- Alves C, Mendes D, Marques FB. Fluoroquinolones and the risk of tendon injury: a systematic review and meta-analysis.. European Journal of Clinical Pharmacology. 2019. PMID 31270563
- Liu C, Kuang X, Li K, Guo X, Deng Q, Li D. Effects of combined calcium and vitamin D supplementation on osteoporosis in postmenopausal women: a systematic review and meta-analysis of randomized controlled trials. Food & Function. 2020. PMID 33237064
- Yao P, Bennett D, Mafham M et al.. Vitamin D and Calcium for the Prevention of Fracture: A Systematic Review and Meta-analysis. JAMA Network Open. 2019. PMID 31860103
Stack Score
How this pair moves the number.
Effect on the composite score
If both Calcium and Ciprofloxacin are in the same stack, this pair applies −5 to your Stack Score (per scored timing-sensitive row).
The full algorithm, the clamping rules, and four worked stacks are documented at /methodology/stack-score.
Check your full routine
One pair was the worked example. NutriStack runs every pair in your stack at once.
Drop in your supplements and prescriptions and the public database surfaces every interaction, synergy, timing rule, and contraindication, every one linked to its primary source.