Most ivermectin interactions trace back to a single mechanism: P-glycoprotein, the transport protein that pumps ivermectin out of the central nervous system. Anything that inhibits it raises brain exposure, and that is where the meaningful risk sits. The other interactions worth knowing are with warfarin and with anything sedating.
Ivermectin's safety rests on being actively excluded from the brain. P-glycoprotein at the blood-brain barrier does that work. Drugs that inhibit it can allow ivermectin to accumulate centrally, and that is the route to confusion, ataxia, seizures and reduced consciousness.
Known P-glycoprotein inhibitors include verapamil, quinidine, amiodarone, ketoconazole and itraconazole, clarithromycin and erythromycin, ritonavir, and cyclosporine. This class of interaction deserves genuine caution rather than a passing mention, and combining them warrants clinical supervision.
Ivermectin can potentiate warfarin and increase INR, raising bleeding risk. Where the two are used together, INR should be monitored more closely around the ivermectin course. Anyone on warfarin should discuss ivermectin with their prescriber before starting.
Ivermectin can cause dizziness and drowsiness on its own. Combined with benzodiazepines, sleep medication, opioids or other sedatives, those effects can compound. Because the shared mechanism involves GABA-related pathways, this is worth taking seriously rather than treating as a routine caution.
Alcohol may increase ivermectin absorption and adds its own sedative effect. Avoiding alcohol around the time of dosing is sensible.
A high-fat meal roughly doubles ivermectin absorption relative to fasting. This is a genuine pharmacokinetic interaction; it simply happens to be a helpful one. It matters mainly for consistency: taking one dose fasted and the next with a large meal produces meaningfully different exposure.
Known hypersensitivity to ivermectin is an absolute contraindication. Beyond that, the situations calling for caution are: pregnancy, where data are limited and treatment is usually deferred if it can safely wait; breastfeeding, where small amounts pass into milk; children under 15 kg, where experience with oral dosing is more limited; and significant liver or kidney impairment, which alters clearance.
One specific and serious situation: in parts of Central Africa where Loa loa is endemic, people with very high Loa loa microfilarial loads can develop severe encephalopathy after ivermectin. Screening is required there. This risk does not apply outside co-endemic regions.
People undergoing cancer treatment are frequently on drugs that affect P-glycoprotein or liver enzymes, and are often immunosuppressed. Ivermectin is not approved for any oncology indication, and combining it with active cancer treatment is a decision for the treating oncologist rather than something to undertake independently.
The same applies to transplant immunosuppression and to biologic therapies for autoimmune disease.
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View products and pricingIvermectin can potentiate warfarin and raise INR, increasing bleeding risk. It is not an absolute prohibition but it does require discussion with your prescriber and closer INR monitoring around the course.
P-glycoprotein inhibitors, because they let ivermectin accumulate in the brain. These include verapamil, quinidine, amiodarone, ketoconazole, itraconazole, clarithromycin, erythromycin, ritonavir and cyclosporine.
It is best avoided around dosing. Alcohol may increase absorption and adds to the dizziness and drowsiness ivermectin can already cause.
Data are limited. Standard practice is to defer treatment during pregnancy where it can safely wait, and to make the decision with a clinician where it cannot.
Potentially. Many cancer therapies affect P-glycoprotein or liver enzymes, and patients are often immunosuppressed. Ivermectin is not approved for any oncology indication, and any combination should be decided by the treating oncologist.