High Quality Content by WIKIPEDIA articles! Extravasation is the accidental administration of intravenously (IV) infused medicinal drugs into the surrounding tissue, either by leakage (e.g., because of brittle veins in very elderly patients), or direct exposure (e.g. because the needle has punctured the vein and the infusion goes directly into the arm tissue). Extravasation of medicinal drugs during intravenous therapy is a side effect that can and should be avoided.