Ivermectin is an anti-parasitic medication that is commonly used to treat infections like lice and scabies. Though it is safe for most people, there are some potential side effects of taking too much ivermectin, including blindness. In rare cases, ivermectin can cause a condition called retinal toxicity, which leads to vision loss. If you experience any changes in your vision after taking ivermectin, be sure to see a doctor right away. A person may take too much ivermectin if they use more than the prescribed dose or if they accidentally ingest the medication rather than applying it topically. While this rarely happens, if it does happen, seek medical attention immediately as there could be permanent damage to the eyesight.