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How to Select the Correct Needle Size For an Injection

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Updated June 09, 2014

Nurse injecting female patient
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A majority of fertility medications come in an injectable form. For most people, this means learning a whole new language and set of skills. Choosing the correct syringe or needle size can be downright confusing if you're new to the whole process. Here, a brief "cheat sheet" to help you along and make your more confident about your purchase.

Decoding Syringe and Needle Labels: What Size Means

Syringes 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 are labeled a little differently. The packaging will have a number, then a G, then another number. The first number (in front of the G) indicates the gauge of the needle. The higher the number, the thinner the needle. The second number indicates the length of the needle. For example, a 22 G 1/2 needle has a gauge of 22 and a length of ½ an inch.

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 Injections Subcutaneous injections go into the fatty tissue below the skin and require a smaller, shorter needle. A needle that is ½ inch to 5/8 of an inch long with a gauge of 25 to 30 is usually sufficient to administer the medication.

Intramuscular Injections Intramuscular 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.villagefertilitypharmacy.com.

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