Which prescription drugs have dangerous interactions with ivermectin (e.g., warfarin, benzodiazepines, antiepileptics)?
Executive summary
Ivermectin has documented interactions with a broad range of prescription drugs, including blood‑thinners (notably warfarin), drugs that depress the central nervous system (such as benzodiazepines and barbiturates), antibiotics and antifungals that alter ivermectin levels (for example, erythromycin, azithromycin, ketoconazole), and agents that modify P‑glycoprotein transport (e.g., fostamatinib, eliglustat) — all of which can increase risk of bleeding, sedation, neurotoxicity, or elevated ivermectin exposure [1] [2] [3] [4] [5]. Public health agencies and drug compendia warn clinicians to review concomitant medications before prescribing ivermectin and to monitor patients closely when these combinations are unavoidable [6] [7].
1. Warfarin and other anticoagulants: a measurable bleeding risk
Post‑marketing reports and regulatory warnings have linked co‑administration of ivermectin with warfarin to increases in INR (a laboratory marker of anticoagulation), and the FDA and prescribing resources explicitly flag blood‑thinners as potential interactants with ivermectin, meaning clinicians should monitor INR and bleeding signs if both are used together [2] [6] [4].
2. Benzodiazepines, barbiturates and other CNS depressants: additive sedation and toxicity
Federal health advisories and clinical summaries note that ivermectin may potentiate the effects of central nervous system depressants such as benzodiazepines and barbiturates, increasing risks of excessive drowsiness, respiratory depression, altered consciousness, and in severe cases overdose‑like presentations — a concern emphasized by the CDC in its ivermectin advisory [3] [8].
3. Antiepileptics and neurologic drugs: vigilance for neurotoxicity and pharmacokinetic complexity
While classic antiepileptic drugs are not singled out universally in every source, the literature on ivermectin’s neurotoxicity and its potential for drug–drug pharmacokinetic interactions (enterohepatic recycling, P‑glycoprotein transport) implies that agents affecting central nervous system function or ivermectin clearance could increase risk of neurologic adverse events; authoritative reviews advise caution and individualized monitoring when combining ivermectin with neurologically active agents [9] [10] [3].
4. Macrolide antibiotics, azoles and certain antiparasitics: raised ivermectin exposure and CNS effects
Clinical reviews and interaction studies report that coadministration of azithromycin, erythromycin and some antifungals like ketoconazole can increase ivermectin concentrations and potentiate central nervous system effects; similarly, combinations used in parasitic therapy (e.g., albendazole) have been shown to raise ivermectin levels and CNS manifestations in some reports, so these combinations warrant caution and possible dose adjustment or monitoring [11] [4] [10].
5. P‑glycoprotein modulators (fostamatinib, eliglustat): mechanistic drivers of toxicity
Drug monographs identify drugs that inhibit P‑glycoprotein (MDR1) — notably fostamatinib and eliglustat — as agents that can increase ivermectin systemic concentrations by reducing efflux transport, a mechanism that predicts higher exposure and thus higher risk of ivermectin‑related adverse effects; professional guidance classifies such combinations as “monitor closely” or require therapy modification [5].
6. How common is this, and where the evidence is thin
Comprehensive checkers list more than a hundred possible interactants with ivermectin, reflecting many theoretical and some reported interactions rather than uniform clinical outcomes; databases such as Drugs.com enumerate 106 interacting medications while clinical guidance (Mayo Clinic, Drugs.com, Medical News Today) urge clinicians to review full medication lists because interactions range from pharmacodynamic (additive CNS depression) to pharmacokinetic (CYP/P‑gp mediated) in nature [1] [12] [13]. Some signals — for example rare INR elevations with warfarin or neurotoxicity reports — are documented in post‑marketing surveillance but not all purported interactions have large controlled studies confirming clinical harm, so risk assessment must be individualized [2] [9].
7. Practical bottom line and unanswered questions
Clinicians should treat warfarin and other anticoagulants, benzodiazepines/barbiturates and P‑gp or CYP inhibitors (macrolides, azoles, fostamatinib, eliglustat, albendazole) as higher‑risk combinations with ivermectin and monitor appropriately (INR, neurologic status, signs of sedation or hypotension), while recognizing that many listed interactions are theoretical or rare and that high‑quality clinical trials quantifying risk for many drug pairs are limited in the public record [2] [3] [5] [11] [1]. If an interaction is suspected, authoritative resources referenced here (FDA, CDC, Drugs.com, drug monographs) provide the basis for monitoring or choosing alternatives [6] [3] [4].