NutriStack
Ciprofloxacin and Green Tea Extract, a caution.
Ciprofloxacin inhibits CYP1A2, the same enzyme that metabolizes caffeine present in green tea extract. This inhibition can roughly double caffeine half-life, leading to jitteriness, insomnia, palpitations, and increased blood pressure during the antibiotic course. People who normally tolerate green tea may notice exaggerated stimulant effects.
One pair, every claim cited. The two substances, the type, the mechanism, the recommendation, and the primary literature.
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What the row says.
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At a glance
- Substances
- Ciprofloxacin and Green Tea Extract
- Pair type
- Caution
- Evidence (highest tier)
- Strong
- Source citations
- 2 sources
- Stack Score effect
- −5 to your Stack Score (per scored caution row).
- Scope
- Supplement × Prescription
- Last verified
- May 30, 2026
Caution · Strong evidence
Caution
What is happening. Ciprofloxacin inhibits CYP1A2, the same enzyme that metabolizes caffeine present in green tea extract. This inhibition can roughly double caffeine half-life, leading to jitteriness, insomnia, palpitations, and increased blood pressure during the antibiotic course. People who normally tolerate green tea may notice exaggerated stimulant effects.
Mechanism. Ciprofloxacin is a moderate-to-strong CYP1A2 inhibitor, reducing clearance of caffeine and other CYP1A2 substrates. Green tea extract contains both caffeine and catechins, and the caffeine accumulates during co-administration.
Recommendation. Reduce green tea extract intake while on ciprofloxacin, especially products with high caffeine content. Watch for jitteriness, insomnia, and palpitations. Return to your usual dose once the antibiotic is finished.
Sources (2)
- Granfors MT, Backman JT, Neuvonen M, Neuvonen PJ. Ciprofloxacin greatly increases concentrations and hypotensive effect of tizanidine by inhibiting its cytochrome P450 1A2-mediated presystemic metabolism. Clin Pharmacol Ther. 2004;76(6):598-606. PMID 15592331
- Parker AC, Preston T, Heaf D, Kitteringham NR, Choonara I. Inhibition of caffeine metabolism by ciprofloxacin in children with cystic fibrosis as measured by the caffeine breath test. Br J Clin Pharmacol. 1994;38(6):573-6. PMID 7888295
Stack Score
How this pair moves the number.
Effect on the composite score
If both Ciprofloxacin and Green Tea Extract are in the same stack, this pair applies −5 to your Stack Score (per scored caution row).
The full algorithm, the clamping rules, and four worked stacks are documented at /methodology/stack-score.
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