Dear Dr. Roach: In several of your columns, either you or a reader has brought up the subject of ivermectin as a treatment for infections or cancer. Is this the same ivermectin that is in my dog's heartworm medication? The label on the dog medication says ivermectin/pyrantel. If it is the same, is it really safe for us humans? -- L.M.H.
Answer: Ivermectin is prescribed for humans and is approved by the Food and Drug Administration for the treatment of certain parasitic infections. Pyrantel is a separate antiparasitic drug that is used for both humans and dogs. The dose for dogs depends on their weight but is much less than the doses used for adult humans for the treatment of serious parasitic infections, like strongyloides.
When used at the correct dose, ivermectin is an effective treatment for many parasitic infections, but people should not use animal doses, even if the medication strength is the same, as they are not formulated for humans. The excipients (the nondrug components of a pill) in animal medications are potentially toxic to humans.
During the pandemic, there were many ivermectin poisonings (which was eventually shown not to be helpful for COVID-19) among people who were using preparations that were intended for external use on horses. Please don't ever use veterinary medications for humans.
Dr. Roach regrets that he is unable to answer individual letters, but will incorporate them in the column whenever possible. Readers may email questions to ToYourGoodHealth@med.cornell.edu.