Intravenous therapy or IV therapy is the infusion of liquid substances directly into a vein

Vein

In the circulatory system, veins are blood vessels that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are the pulmonary and umbilical veins, both of which carry oxygenated blood to the heart...

. The word intravenous simply means "within a vein

Vein

In the circulatory system, veins are blood vessels that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are the pulmonary and umbilical veins, both of which carry oxygenated blood to the heart...

". Therapies administered intravenously are often called specialty pharmaceuticals. It is commonly referred to as a drip because many systems of administration employ a drip chamber

Drip chamber

A drip chamber is a device used to allow gas to rise out from a fluid so that it is not passed downstream. They are commonly employed in delivery systems of intravenous therapy and act to prevent air embolism....

, which prevents air from entering the blood stream (air embolism

Air embolism

An air embolism, or more generally gas embolism, is a pathological condition caused by gas bubbles in a vascular system. The most common context is a human body, in which case it refers to gas bubbles in the bloodstream...

), and allows an estimation of flow rate.

Intravenous therapy may be used to correct electrolyte

Electrolyte

In chemistry, an electrolyte is any substance containing free ions that make the substance electrically conductive. The most typical electrolyte is an ionic solution, but molten electrolytes and solid electrolytes are also possible....

 imbalances, to deliver medications, for blood transfusion

Blood transfusion

Blood transfusion is the process of receiving blood products into one's circulation intravenously. Transfusions are used in a variety of medical conditions to replace lost components of the blood...

 or as fluid replacement

Fluid replacement

Fluid replacement or fluid resuscitation is the medical practice of replenishing bodily fluid lost through sweating, bleeding, fluid shifts or other pathologic processes. Fluids can be replaced via oral administration , intravenous administration, rectally, or hypodermoclysis, the direct injection...

 to correct, for example, dehydration

Dehydration

In physiology and medicine, dehydration is defined as the excessive loss of body fluid. It is literally the removal of water from an object; however, in physiological terms, it entails a deficiency of fluid within an organism...

.

Compared with other routes of administration

Route of administration

A route of administration in pharmacology and toxicology is the path by which a drug, fluid, poison, or other substance is taken into the body.-Classification:Routes of administration are usually classified by application location...

, the intravenous route is the fastest way to deliver fluids and medications throughout the body.