What are the most common medications that interact with ivermectin?
Executive summary
Ivermectin has a wide range of documented and potential drug interactions; clinical resources list over 100 drugs that can interact with oral ivermectin, and the most commonly flagged ones fall into a few predictable classes — anticoagulants (notably warfarin), macrolide antibiotics (e.g., erythromycin), azole antifungals (e.g., ketoconazole), CYP/P‑glycoprotein modifiers (inducers like rifampicin and inhibitors), certain statins and other myopathy‑risk drugs, anticonvulsants (e.g., phenytoin), and alcohol — but strength and clinical significance vary with dose, formulation and patient factors [1] [2] [3] [4].
1. Warfarin and other anticoagulants: a bleeding risk flagged across drug checkers
Major drug‑interaction databases and patient information sites specifically single out warfarin as a drug to discuss with a prescriber before taking ivermectin, reflecting concerns that co‑administration can alter warfarin’s effects and require monitoring of anticoagulation status [1] [3] [2].
2. Macrolide antibiotics and azole antifungals: raise ivermectin levels by blocking metabolism
Macrolides such as erythromycin and azole antifungals like ketoconazole are listed among common interactants because they can inhibit pathways (including CYP3A4 and P‑glycoprotein) that handle ivermectin, thereby increasing systemic exposure and potential adverse effects [1] [4] [2].
3. CYP/P‑glycoprotein inducers and inhibitors: bidirectional effects on ivermectin levels
Strong inducers such as rifampicin can speed ivermectin clearance and potentially reduce efficacy, while inhibitors (some antivirals, azoles, macrolides and protease inhibitors) can elevate ivermectin concentrations — a theme emphasized in pharmacokinetic reviews and interaction summaries that stress transporter and CYP involvement [4] [5] [6].
4. Statins, fibrates and other myopathy‑risk drugs: overlapping toxicity concerns
Clinical reviews note that ivermectin given with commonly used statins or other agents linked to myopathy or rhabdomyolysis may increase the risk or severity of muscle injury, making this a commonly cited interaction class to monitor in practice [4].
5. Anticonvulsants and other enzyme‑inducing drugs: reduced ivermectin effect possible
Anticonvulsants such as phenytoin are listed as drugs that may reduce ivermectin levels or blunt its effect through enzyme induction, and multiple patient information pages advise clinicians to consider such interactions when dosing [7] [8].
6. Antibiotics, antivirals, immunomodulators and many others: a long tail of potential interactions
Beyond the headline drugs, systematic interaction compilations and reviews enumerate many antibiotics (erythromycin, benzylpenicillin), antivirals (grazoprevir, asunaprevir and others), immunomodulators like cyclosporine, hormonal agents, and numerous oncology agents as affecting ivermectin’s metabolism or being affected by it — underscoring that interaction evidence ranges from clinical reports to pharmacologic plausibility [4] [6] [9].
7. Alcohol, formulation differences and clinical context: modifiers of interaction risk
Alcohol can amplify certain ivermectin side effects such as dizziness and sedation and is explicitly noted as a food/ethanol interaction in interaction databases, while topical ivermectin formulations have much lower systemic absorption and thus lower interaction risk compared with oral tablets [10] [3] [11].
8. How confident can clinicians be? evidence limits and practical advice
Authoritative reviews stress that human pharmacokinetic data remain incomplete and many listed interactions are mechanistic or extrapolated from transporter/CYP data rather than large clinical trials; national compendia nevertheless list roughly 100–120 medicines as potential interactants, so the practical approach is individualized review, monitoring (e.g., INR with warfarin), and dose adjustments when strong inhibitors/inducers are co‑prescribed [5] [1] [2] [12].