How does ivermectin interact with other common medications and herbal supplements?
Executive summary
Ivermectin has known interactions with anticoagulants (notably warfarin) and alcohol, and drug interaction checkers list more than 100 possible interacting medicines; clinical guidance warns that even approved ivermectin doses can change how people metabolize other drugs [1] [2] [3]. Major consumer sites and regulators urge patients to tell clinicians about all prescription, OTC, vitamins and herbs before taking ivermectin because interactions and increased side effects have been reported [4] [5] [3].
1. How regulators and major drug sources frame the interaction risk
Regulatory and reference sources emphasize caution: the FDA explicitly states that even approved human doses of ivermectin can interact with other medications such as blood‑thinners and urges filling prescriptions through legitimate pharmacies [3]. Drugs.com and Medical News Today both advise patients to disclose all prescription, over‑the‑counter, vitamin and herbal use before taking ivermectin to avoid interactions and note alcohol can increase some side effects [5] [4].
2. The clearest documented interaction: anticoagulants (warfarin and “blood‑thinners”)
Multiple sources single out anticoagulants as a concrete concern. Medscape flags that ivermectin “increases effects of warfarin” though the mechanism is unspecified, and both FDA and the New York Times note interactions with blood‑thinners as a known safety issue [1] [3] [6]. That pattern — repeated mention of enhanced anticoagulant effect — is the strongest, repeatedly reported interaction in current coverage [1] [3] [6].
3. Alcohol, CNS effects, and other general cautions
Consumer drug guides list an alcohol/food interaction and warn that drinking alcohol can amplify certain ivermectin side effects [2] [5]. The broader concern in coverage is that ivermectin can alter drug metabolism generally, which could change blood levels and effects of co‑medications — a rationale used by experts to caution about combining it with other therapies [6] [3].
4. Lists and checkers show many possible interactions — but vary in detail
Interaction databases report different scopes: Drugs.com notes 106 interacting drugs plus one alcohol/food interaction [2], while DrugBank and other references flag many off‑target or transporter‑related interactions [7]. These resources serve as screening tools: they flag potential interactors but do not always agree on clinical significance, and some entries rely on theoretical mechanisms such as P‑glycoprotein transport [7] [1].
5. Herbal supplements and vitamins: what the sources actually say
Available sources repeatedly advise telling clinicians about vitamins, herbs and supplements, but they do not list specific herbal agents with confirmed ivermectin interactions in these excerpts. Medical News Today and Drugs.com explicitly tell patients to disclose herbs and supplements to avoid interactions, yet the current reporting does not name particular herbal supplements with proven interactions [4] [5]. Therefore: specific herb‑ivermectin interactions are not detailed in the provided material (not found in current reporting).
6. Conflicting views and limits of the evidence base
DermNet NZ states “no significant drug interactions with ivermectin are recognised,” a stance that contrasts with regulator warnings and database listings [8]. This highlights heterogeneity: some specialist summaries see few clinically meaningful interactions at standard doses, while drug‑interaction databases and regulators emphasize caution and list numerous potential interactions [8] [2] [3]. The disagreement likely reflects differences between theoretical/rare interactions flagged by databases and clinical judgments about routine significance.
7. Practical takeaways for patients and clinicians
Clinicians should review anticoagulant therapy carefully if prescribing ivermectin and monitor INR or equivalent parameters if warfarin is involved, since multiple sources warn of increased anticoagulant effects [1] [3]. Patients should avoid alcohol while taking ivermectin because it can worsen side effects [5] [2]. For vitamins and herbal supplements, tell your prescriber — the sources urge disclosure but do not provide validated lists of herb interactions in the provided reporting (p1_s1; [5]; not found in current reporting).
8. Why this matters now: policy and misuse influence risk
Wider availability and politicized promotion of ivermectin have driven increased use, poison‑center reports and more off‑label exposure — factors that raise the stakes for interactions in the real world [9] [10] [11]. As access expands, pharmacists and clinicians bear responsibility to check interactions and counsel patients, balancing evidence, safety and patient concerns [10] [3].
Limitations: this analysis is limited to the provided sources; they contain safety warnings, database listings and some conflicting summaries, but do not provide a comprehensive, peer‑reviewed catalog of every proven ivermectin–herb or drug interaction beyond the anticoagulant and alcohol cautions cited above (not found in current reporting).