Ciprofloxacin and Clozapine interaction

Ciprofloxacin and Clozapine: both prescribing labels flag this combination with the strongest language, such as a contraindication, a boxed warning, or an instruction to avoid it.

Major

Do not combine without a prescriber's guidance. The label language below is the strongest FDA uses.

What the FDA labels say

From the Ciprofloxacin label · effective 2026-06-30

Major

Avoid use in patients with known prolongation, those with hypokalemia, and with other drugs that prolong the QT interval.

Warnings and precautionsby drug classView label on DailyMed
Major

Table 8: Drugs That are Affected by and Affecting Ciprofloxacin Drugs That are Affected by Ciprofloxacin Drug(s) Recommendation Comments Tizanidine Contraindicated Concomitant administration of tizanidine and ciprofloxacin is contraindicated due to the potentiation of hypotensive and sedative effects of tizanidine [see Contraindications ( 4.2 )].

Drug interactionsby drug classView label on DailyMed
Moderate

Co-administration of ciprofloxacin and other drugs primarily metabolized by CYP1A2 (for example, theophylline, methylxanthines, caffeine, tizanidine, ropinirole, clozapine, olanzapine and zolpidem), results in increased plasma concentrations of the co-administered drug and could lead to clinically significant pharmacodynamic adverse reactions of the co-administered…

Warnings and precautionsnames ClozapineView label on DailyMed
Moderate

Clozapine Use with caution Careful monitoring of clozapine associated adverse reactions and appropriate adjustment of clozapine dosage during and shortly after co-administration with ciprofloxacin are advised.

Drug interactionsnames ClozapineView label on DailyMed
Moderate

…syndrome, uncorrected electrolyte imbalance, such as hypokalemia or hypomagnesemia and cardiac disease, such as heart failure, myocardial infarction, or bradycardia), and patients receiving Class IA antiarrhythmic agents (quinidine, procainamide), or Class III antiarrhythmic agents (amiodarone, sotalol), tricyclic antidepressants, macrolides, and antipsychotics.

Warnings and precautionsby drug classView label on DailyMed

From the Clozapine (Clozaril) label · effective 2025-06-06

Moderate

• Concomitant use of Strong CYP1A2 Inhibitors: Reduce CLOZARIL dose to one-third when coadministered with strong CYP1A2 inhibitors (e.g., fluvoxamine, ciprofloxacin, enoxacin).

Drug interactionsby drug classView label on DailyMed
Moderate

CYP1A2 Inhibitors Concomitant use of CLOZARIL and CYP1A2 inhibitors can increase plasma levels of clozapine, potentially resulting in adverse reactions.

Drug interactionsby drug classView label on DailyMed
Moderate

Reduce the CLOZARIL dose to one-third of the original dose when CLOZARIL is coadministered with strong CYP1A2 inhibitors (e.g., fluvoxamine, ciprofloxacin, or enoxacin).

Drug interactionsby drug classView label on DailyMed
Moderate

The CLOZARIL dose should be increased to the original dose when coadministration of strong CYP1A2 inhibitors is discontinued [see Dosage and Administration ( 2.7 ), Clinical Pharmacology ( 12.3 )] .

Drug interactionsby drug classView label on DailyMed
Minor

Moderate or weak CYP1A2 inhibitors include oral contraceptives and caffeine.

Drug interactionsby drug classView label on DailyMed

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Not medical advice. Interaction Checker quotes FDA label text and NIH fact sheets. Whether an interaction matters for you depends on doses, timing, kidney and liver function, and other conditions. Confirm with a pharmacist or prescriber.