Editing Nursing Skills and Procedures (section)

== Injections ==

=== Route comparison ===
{| class="wikitable"
! Route !! Angle !! Needle !! Usual volume !! Sites
|-
| Intradermal || 5 to 15 degrees, bevel up || 26 to 27 gauge, 3/8 to 5/8 inch || 0.01 to 0.1 mL || Inner forearm, upper back
|-
| Subcutaneous || 45 to 90 degrees || 25 to 27 gauge, 3/8 to 5/8 inch || up to about 1 mL || Abdomen, posterior upper arm, anterior thigh, upper back
|-
| Intramuscular || 90 degrees || 20 to 25 gauge, 1 to 1.5 inch || up to 3 mL in a large adult muscle || Ventrogluteal, deltoid, vastus lateralis
|}

=== Intradermal ===
Used for tuberculin skin testing and allergy testing. The needle is inserted bevel up at a shallow angle until the bevel is just covered, and a 6 to 10 mm wheal should form. The site is not massaged. A tuberculin test is read at 48 to 72 hours by palpating and measuring induration, not erythema. Interpretation thresholds are 5 mm in the immunosuppressed and close contacts of active cases, 10 mm in higher-risk groups such as recent immigrants, injection drug users, and health care workers, and 15 mm in people with no known risk factors. A positive skin test indicates exposure, not active disease, and is followed by chest imaging and symptom assessment.

=== Subcutaneous ===
Angle is chosen by tissue depth: 90 degrees when at least 2.5 cm, or one inch, of tissue can be grasped, and 45 degrees when only about 1.25 cm can be grasped. Aspiration is not performed for subcutaneous injections.
* '''Heparin''': give in the abdomen at least 5 cm, about two inches, away from the umbilicus, at 90 degrees, do not aspirate, and do not massage, because both increase hematoma risk. Rotate sites. Low molecular weight heparin such as enoxaparin comes in a prefilled syringe with an air bubble that is not expelled, and the skin fold is held throughout injection.
* '''Insulin''': use an insulin syringe with units marked, inject at 90 degrees, do not aspirate, and do not massage. Absorption is fastest from the abdomen, then arm, then thigh, then buttock. Rotate within one anatomic region rather than across regions to keep absorption consistent, and space sites about 2.5 cm apart to prevent lipohypertrophy. When mixing, draw air into the intermediate-acting cloudy insulin first, then air into the clear regular insulin, then withdraw the clear regular insulin, then the cloudy: clear before cloudy. Insulin glargine, detemir, and degludec are never mixed with other insulins.

=== Intramuscular ===
* '''Ventrogluteal''' is the preferred adult site for volumes above 2 mL and for viscous or irritating medications. It is located by placing the palm on the greater trochanter, the index finger on the anterior superior iliac spine, and the middle finger along the iliac crest, then injecting into the V. It is free of major nerves and vessels.
* '''Deltoid''' holds about 1 mL, up to 2 mL in a well-developed adult, and is located 2.5 to 5 cm below the acromion process. It is the standard adult vaccine site. Injection too high or too deep risks shoulder injury and axillary nerve damage.
* '''Vastus lateralis''' is the preferred site for infants under 12 months and is acceptable at all ages. The dorsogluteal site is no longer recommended because of sciatic nerve injury risk.
* '''Z-track''' technique is now recommended for all intramuscular injections. Pull the skin laterally about 2.5 cm, insert at 90 degrees, inject slowly, wait about 10 seconds, withdraw, then release the skin so the tissue planes seal and medication cannot track back to the subcutaneous tissue. Do not massage.
* Routine aspiration before injection is no longer recommended for vaccines given in the deltoid or vastus lateralis. Facility policy and instructor expectation vary for other intramuscular medications, and aspiration remains a common expected answer for gluteal injections.

Never recap a used needle, activate the safety device immediately, and dispose of sharps at the point of use. Air bubbles are expelled before injection except when the manufacturer directs otherwise, as with prefilled enoxaparin.