subcutaneous injection, the introduction of a hypodermic needle into the subcutaneous tissue beneath the skin, usually on the upper arm, thigh, or abdomen. A 24- or 27-gauge needle 2 cm long is used. The drug is prepared and drawn into the syringe. The cleansed area of skin is held by the thumb and forefinger to tense and steady the injection site. The needle is inserted at an angle of 45 to 90 degrees, piercing the skin quickly and advancing steadily to minimize the pain. The barrel or plunger is withdrawn slightly to ascertain whether the syringe of the needle has inadvertently entered a blood vessel. If no blood is aspirated, the drug is injected slowly, the needle is withdrawn, and the skin is massaged gently (unless contraindicated) with a sterile alcohol sponge. Certain drugs that are extremely irritating to the skin are injected into the deep subcutaneous tissues by using a variation of the technique. The skin tissue overlying the injection site is grasped with the thumb and forefinger but elevated in a roll, rather than tensed and flattened. The angle of injection may be as great as 90 degrees to the skin. Heparin, insulin, and emetine are injected in this way. If subcutaneous injections are repeated, each is performed at least 5 cm from the previous site. A diagram of a plan for the rotation of injection sites helps to prevent overuse of one area of skin.
