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Registered Nurse (RN)
Fundamentals of Nursing
Basics of Medication Administration
Needle Sizes and Uses

Mnemonic for Needle Gauge & Sizes by Picmonic

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Needle Sizes and Uses

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Needle Sizes and Uses

Needle Sizes and Uses
Needles are used to administer various medications. The length of the needle will depend upon the type of injection and the gauge size will depend upon the type of medication. Be sure to select the appropriate needle and adjust the size based on height and weight. For subcutaneous injections, a needle length between 3/8 to 5/8 of an inch should be used, while intramuscular injections are typically between 1 and 1.5 inches.
Adjust Size Based on Height/Weight
Different Size Needles for Different Size People

Needles come in varying sizes because our patients come the same way. Remember to increase needle sizes for obese or larger patients and consider smaller needle sizes for thin patients or younger children.

Subcutaneous Injections

SUBQ injections penetrate through the dermis directly into the subcutaneous tissue. They are often used for injections like insulin and heparin. Remember, you can give SUBQ injections at 45 or 90 degrees in areas like the upper arms, abdomen, or anterior thighs.

3/8 or 5/8 inch
(3) Tree over (8) Ball or (5) Hand over (8) Ball

You can always remember to use a smaller needle size for SUBQ injections, like a 3/8 or 5/8 inch, by remembering that you would never want a 3-inch long needle injected into your abdomen.

Intramuscular (IM)

IM injections penetrate directly into the vascular muscles like the deltoid, ventrogluteal, or vastus lateralis. Because of the depth of muscle beneath the subcutaneous tissue, remember to select a longer needle. Obese patients may require up to 3-inch long needles. Ouch!

1-1.5 inches
(1) Wand to (1.5) Wand Hand

Adults, on average, require needle sizes of 1-1.5 inches in length. Obese patients sometimes require up to a 3-inch-long needle to penetrate the additional adipose tissue. Be sure to consider a smaller needle for smaller patients, like children and thinner adults. This consideration is especially important for elderly patients with atrophied muscles. These patients may only require a 1/2 to 1-inch needle to reach the muscle.


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