Determine the gauge of needle to use for an injection according to the viscosity of the medication, the size and age of the patient and his mobility status, and the absorption rate wanted, explains Nursing Link. Intramuscular injections also require different types of gauges than subcutaneous ones.
Commonly, intramuscular injections require gauge sizes of 21 to 23 for an adult and 25 to 27 for a child. Intramuscular injections are often necessary when administering viscous or irritating drugs, says Nursing Link. Because there are fewer pain receptors in intramuscular tissue than in the skin, the body can quickly absorb such drugs without causing discomfort. The person injecting should take care to avoid hitting any blood vessels when performing such injections. Sites well suited for intramuscular injections include the deltoid and the dorsal gluteal area.
The provider administers subcutaneous injections in the connective tissue right beneath the top layer of skin, explains Nursing Link. These types of injections require gauge sizes of 25 to 27 for both adult and children. Injections to administer some newer medications, such as some prescribed to patients with diabetes, require very thin needles with gauge sizes of 30 and 31. Administration of subcutaneous injections usually occurs in the upper arm, thigh or abdominal areas in both children and adults.