mainlining

Origin

The invention of the hypodermic needle in the mid-19th century revolutionized medicine, but it also opened a new, more potent avenue for drug use. As the practice of injecting substances directly into the bloodstream became more prevalent in the 20th century, a new vocabulary emerged to describe this direct and powerful method. "Mainlining" specifically referred to targeting the body's most significant veins—the "main lines" of the circulatory system—to deliver drugs straight to the heart and brain, ensuring the most immediate and intense effect. This stark, descriptive term quickly entered the lexicon, capturing the unadulterated immediacy and dangerous potency of intravenous drug administration.