How to Select the Correct Needle Size for an Injection

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By Nicole Galan, RN
About.com Health's Disease and Condition content is reviewed by the Medical Review Board

Decoding Syringe and Needle Labels: What Size Means

are labeled in terms of how much liquid they can hold. For example, the packaging might say '3ml,' meaning that the syringe can measure up to 3ml of fluid. One cc, or cubic centimeter, is the same amount as one mL. When selecting a syringe, make sure that the amount of medicine or fluid that you need to draw up will fit into the syringe (don’t use a 1mL syringe when you need to draw up 2mLs, for example).
Needles

What Do You Need?

The type of syringe/needle you need to give yourself whatever medication you've been prescribed should be outlined by your doctor or pharmacist. If not, or if you don't recall, ask. Here, a sense of what is usually recommended for each type of injection:
Subcutaneous InjectionsSubcutaneous injections
go into the muscle below the subcutaneous layer, so the needle must be thicker and longer to ensure that the medicine is being injected into the proper tissue. Twenty (20) or 22 G needles that are an inch or an inch and a half long are usually appropriate for this type of injection. A person who is thin, with very little fatty tissue can use the inch long needle; a heavier person may need to use the inch and a half long needle.
Source:
Common Questions Fact Sheet. Village Fertility Pharmacy. http://www.villagepharmacy.com.