Intraperitoneal injection or IP injection is the injection of a substance into the peritoneum (body cavity). IP injection is more often applied to animals than to humans. In general, it is preferred when large amounts of blood replacement fluids are needed, or when low blood pressure or other problems prevent the use of a suitable blood vessel for intravenous injection.
In animals, IP injection is used predominantly in veterinary medicine and animal testing for the administration of systemic drugs and fluids due to the ease of administration compared with other parenteral methods.
In humans, the method is widely used to administer chemotherapy drugs to treat some cancers, in particular ovarian cancer. Although controversial, this specific use has been recommended as a standard of care.