The size of the needle for an intramuscular (IM) injection depends on the age, weight, and muscle mass of the patient, as well as the injection site and the volume of the material to be administered. Here are some general guidelines:
-
For infants younger than 12 months of age, a 5/8 inch (16 mm) needle with a 23-25 gauge is recommended for subcutaneous injections in the thigh. For intramuscular injections in the vastus lateralis muscle of the anterolateral thigh, a 5/8 inch (16 mm) needle with a 22-25 gauge is recommended for neonates (28 days and younger), and a 1 inch (25 mm) needle with a 22-25 gauge is recommended for infants aged 1-12 months.
-
For children aged 1-18 years, the needle length and injection site for IM injections depend on the age and weight of the child. The deltoid muscle is preferred, but the anterolateral thigh can also be used. The recommended needle length ranges from 5/8 inch (16 mm) to 1.5 inches (38 mm), depending on the age and weight of the child, and the gauge ranges from 23-25.
-
For adults, the deltoid muscle is most often used as the site for IM injections. The recommended needle length is usually 1-1.5 inches (25-38 mm), and the gauge is usually 22-25. However, a longer or shorter needle may be needed depending on the patients weight. An alternate site for IM injection in adults is the anterolateral thigh muscle, and the needle length and gauge are the same as when the deltoid muscle is used.
-
Some experts allow intramuscular injection with a 5/8 inch (16 mm) needle for men and women weighing less than 60 kg, but ONLY if the skin is stretched tightly and subcutaneous tissues are not bunched. If the subcutaneous and muscle tissue are bunched to minimize the chance of striking bone, a 1 inch (25 mm) needle or larger is required to ensure intramuscular administration.
It is important to choose the proper needle length to ensure that the vaccine or medication reaches the desired tissue and provides an optimal immune response while reducing the likelihood of injection-site reactions.
