Is there a patent on ivermectin?

Short answer: there were patent protection rights on ivermectin (and on related derivatives and uses), but the original patents have largely expired in most parts of the world. Ivermectin is now generic in many markets. That said, there can still be active patents in some jurisdictions for specific formulations, dosage forms, veterinary uses, or particular methods of manufacture, so status can vary by country and application.

If you want a precise answer, tell me the country or region and the specific aspect you’re interested in (the compound itself, a particular formulation, or a use). I can help look up the current legal status in that jurisdiction using patent databases (e.g., USPTO, EPO, WIPO Patentscope, Google Patents).