Ivermectin is a broad spectrum antiparasitic medication used in both human and veterinary medicine. Its primary action targets certain ion channels in parasites that are not present or are far less sensitive in mammals. By binding to these channels, ivermectin increases the flow of chloride ions into parasite nerve cells. The resulting paralysis prevents the parasites from feeding or moving, leading to their death and eventual elimination from the body. In human medicine ivermectin is most commonly administered in oral form as tablets or liquid suspension. A single dose is calculated according to body weight at approximately 0.7 milligrams per kilogram. This regimen is effective against intestinal strongyloidiasis and onchocerciasis the cause of river blindness. In tropical and subtropical regions mass drug administration campaigns distribute ivermectin to entire communities to prevent the spread of these debilitating diseases. Dermatologists prescribe oral or topical ivermectin for conditions such as scabies and head lice. For scabies a single oral dose often suffices but may be repeated after two to four weeks if symptoms persist. The topical cream formulation is applied in a thin layer to clean dry skin once a day typically at bedtime and washed off in the morning. This approach limits systemic exposure while directly targeting mites in the skin. Most people tolerate ivermectin very well. Mild nausea headache or light dizziness may occur during the first day after treatment but tend to subside quickly. Rarely patients experience rash or itching as the parasites die. Because the drug is processed by the liver and eliminated by the kidneys dose adjustments may be necessary for individuals with significant organ impairment. In recent years ivermectin has attracted attention for potential antiviral activity but current clinical trials have not produced convincing evidence of benefit against acute viral infections. Health authorities caution against using the drug outside of approved indications without guidance from a qualified medical professional. When used correctly under a doctor’s supervision ivermectin remains one of the safest and most effective treatments for a variety of parasitic diseases. Its proven track record and ease of administration make it an invaluable tool in global public health efforts to reduce the burden of infections that disproportionately affect vulnerable populations.