Intravenous (IV) therapy, which delivers fluids and medication directly into a vein, is a procedure used countless times daily across modern healthcare systems. This technique allows for the immediate distribution of substances throughout the bloodstream, bypassing the digestive system for rapid effect. The history of this common practice is not marked by a single invention but rather a centuries-long progression of experimental failures, scientific breakthroughs, and technological advancements. It matured into a reliable medical procedure through the gradual refinement of chemical understanding and specialized equipment.
The Early Concept and Failed Experiments of the 17th Century
The initial concept of injecting substances directly into the circulatory system emerged shortly after the discovery of blood circulation in the early 17th century. English architect and scientist Christopher Wren performed the earliest confirmed intravenous experiments, conducting trials on dogs in 1656 at Oxford. He devised a crude delivery system consisting of an animal bladder, which functioned as a syringe, connected to a sharp goose quill inserted into the animal’s vein.
Wren and his colleagues injected various substances, such as wine, beer, and opium, not for therapy but to observe the systemic effects of bypassing the gut. They sought to learn if orally taken medications would be effective when delivered directly into the blood. These attempts demonstrated that substances could enter the bloodstream this way, but the lack of sterile technique and precise knowledge of physiology made the procedure too dangerous for human application. Attempts by physicians in Germany in the 1660s resulted in frequent and severe adverse reactions, leading to the rapid abandonment of the practice for nearly 150 years.
The Critical Breakthrough: Fluid Replacement and Saline
The transformation of intravenous injection into a therapeutic tool occurred during the cholera pandemic in the early 19th century. In 1831, Scottish physician William Brooke O’Shaughnessy analyzed the blood and excreta of cholera patients, observing a significant loss of water and “saline matters.” He deduced that the fatal effects of cholera were caused by severe dehydration and electrolyte depletion, proposing that these lost fluids needed replacement.
Following O’Shaughnessy’s analysis, Dr. Thomas Latta, a physician in Leith, Scotland, was the first to apply this theory clinically. In 1832, Latta began administering a solution of salt and water directly into the veins of severely ill cholera patients. He used custom-made silver needles and a modified enema syringe to inject the solution into the basilic vein.
Latta’s initial results were dramatic; he observed patients near death regain consciousness and strength almost immediately after the infusion began. This marked the invention of IV therapy as a life-saving medical treatment focused on volume replacement. Although Latta’s work was initially met with skepticism and the practice disappeared after the epidemic subsided, his successful use of saline established the foundational concept for all subsequent fluid therapy.
Standardization of Equipment and Sterilization
For IV therapy to become a safe, routine treatment, significant improvements in equipment and procedure began in the mid-19th century. The development of the hypodermic needle was a major mechanical step, credited to Irish physician Francis Rynd in 1844, who created a hollow steel instrument for injections. This was followed by the all-glass syringe designed by Alexander Wood in 1851, which allowed physicians to accurately measure the dosage of the injected fluid.
These early metal and glass devices were reused, carrying a high risk of infection. The critical procedural safety step came with the widespread adoption of antiseptic principles in the late 19th century, following the work of Louis Pasteur and Robert Koch. This led to the development of sterilization techniques, such as the autoclave, and the implementation of aseptic practices for preparing solutions and cleaning equipment. The later Luer-lock system provided a standardized, secure connection between the syringe and the needle, minimizing contamination and leakage. These advancements transformed the high-risk injection into a repeatable, safer medical intervention.
Widespread Adoption and Modern IV Practice
The institutionalization of IV therapy as a routine medical procedure was accelerated by the massive casualties of 20th-century conflicts. The World Wars created an urgent, large-scale need for reliable methods of blood transfusion and fluid resuscitation on the battlefield. This necessity drove the commercial production of standardized, sterile IV solutions in the 1930s and pushed for the training of non-physicians, such as nurses, to administer the infusions.
The introduction of disposable materials in the mid-20th century completed the transition to the modern IV system. Previously, reusable metal needles were sharpened and sterilized by hand. The invention of the disposable plastic catheter, which slides over the needle and remains in the vein, revolutionized patient comfort and safety by reducing the risk of vein damage and infection. Today, the use of flexible plastic bags for sterile solutions and single-use plastic catheters has made IV therapy one of the most common and reliable medical interventions globally.