is secreted in very low concentration in breast milk. It remains unclear if ivermectin is safe during pregnancy. Adverse effects Side effects, although uncommon, include fever, itching, and skin rash when taken by mouth; and red eyes, dry skin, and burning skin when used topically for head lice. It is unclear if the drug is safe for use during pregnancy, but it is probably acceptable for use during breastfeeding. Ivermectin is considered relatively free of toxicity in standard doses (around 300 µg/kg). Based on the data drug safety sheet for ivermectin, side effects are uncommon. However, serious adverse events following ivermectin treatment are more common in people with very high burdens of larval Loa loa worms in their blood. Those who have over 30,000 microfilaria per milliliter of blood risk inflammation and capillary blockage due to the rapid death of the microfilaria following ivermectin treatment. One concern is neurotoxicity after large overdoses, which in most mammalian species may manifest as central nervous system depression, ataxia, coma, and even death, as might be expected from potentiation of inhibitory chloride channels. Since drugs that inhibit the enzyme CYP3A4 often also inhibit P-glycoprotein transport, the risk of increased absorption past the blood-brain barrier exists when ivermectin is administered along with other CYP3A4 inhibitors. These drugs include statins, HIV protease inhibitors, many calcium channel blockers, lidocaine, the benzodiazepines, and glucocorticoids such as dexamethasone. During the course of a typical treatment, ivermectin can cause minor aminotransferase elevations. In rare cases it can cause mild clinically apparent liver disease. To provide context for the dosing and toxicity ranges, the of ivermectin in mice is 25 mg/kg (oral), and 80 mg/kg in dogs, corresponding to an approximated human-equivalent dose LD50 range of 2.02-43.24 mg/kg, which is far in excess of its FDA-approved usage (a single dose of 0.150-0.200 mg/kg to be used for specific parasitic infections). While ivermectin has also been studied for use in COVID-19, and while it has some ability to inhibit SARS-CoV-2 in vitro, achieving 50% inhibition in vitro was found to require an estimated oral dose of 7.0 mg/kg (or 35x the maximum FDA-approved dosage), high enough to be considered ivermectin poisoning. Despite insufficient data to show any safe and effective dosing regimen for ivermectin in COVID-19, doses have been taken far in excess of FDA-approved dosing, leading the CDC to issue a warning of overdose symptoms including nausea, vomiting, diarrhea, hypotension, decreased