Nursing Students' Helpful Hints: How to Choose the Right Syringe/needle for the Job

Here's the lowdown on syringes and needles for adults:

Insulin syringes-Use only for insulin!!!

Insulin comes in a variety of ways but the universal is U-100 insulin, meaning that there are 100 units of insulin in 1 ml or cc. U-100 is primarily used in the United States except for the most insulin resistant. The cap of the insulin syringe and the insulin vial are universally colored. For example, U-100 insulin syringe and insulin vial cap are orange in color. ONLY use U-100 insulin with U-100 syringes. There is one exception: The Humalog vial has a burgundy rim to differentiate between Regular and Humalog, but it is still U-100 concentration. It will be on the vial so no need to guess.

There are two types of U-100 insulin syringes-One holds up to 50 units of insulin (sometimes called low dose) and the tick marks are one unit. The other holds up to 100 units of insulin and the tick marks are equal to 2 units. It doesn't matter which one you have or use just be sure you are drawing up the right amount. Keep in mind that if you are giving more than 50 units you need the larger syringe. A frequent student mistake is to draw up something like 20 units while intending to draw up 2 units. That's 10 times the dose you intended. Both syringes have a pre-attached 5/8 inch needle that cannot be removed. While insulin syringes are 1ml I would never use it in place of a 1 ml syringe because the markings are in units not ml there is a greater chance of error.

3cc syringe

Usually used for IM injections or can be used for mixing or drawing up other medications. The key is will your dose fit in this size. Generally use the smallest syringe that will hold the dose except when using central lines in which case you will need to use at least a 10ml syringe.

5cc/7cc syringe

Used for mixing or drawing up medications

10cc/12cc syringe

Used for mixing or drawing up other medications. The larger the syringe the lower the pressure of the flow. This is why they are required for central line flushing to avoid damaging the line. Also they are used to deflate foley balloons and for urine specimen collection from the port of a foley.

TB syringe (1ml syringe)

Used for Heparin SQ or TB Intradermal skin testing. It has 0.1cc markings with the entire syringe holding 1 cc of medication. You should never draw up insulin in this syringe there is just such a risk of error because the syringe is measured in ml and not units. Unless you are working in some impoverished nation doing relief work and that is all you have there is no need to substitute for an insulin syringe.

Needles for adult administration:

25-27 gauge 3/8 to 5/8 inch-SQ injection

21-25 gauge 1 to 11/2 inch - IM injection (need 2 needles)

18-21 gauge 1 inch-Good size for drawing up from vials

Additional Tip: Protect yourself from needlesticks! Always use needle free systems when possible and never defeat safety mechanisms. Never recap a dirty needle. If recapping after drawing up a medicine use a one handed technique to get the cap on.