How to Select the Correct Needle Size For an Injection

Selecting the right needle and syringe is important for fertility injections

Nurse injecting female patient
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Most fertility medications come in an injectable form. If you've never taken an injectable medication before, this means learning a whole new language and skill set. Choosing the correct syringe or needle size can be downright confusing if you're new to the whole process. Here are some tips to help make the process easier.

What Syringe and Needle Size Means

Syringes are labeled in terms of how much liquid they can hold.

For example, if the packaging says "3mL," that means the syringe can measure up to 3ml of fluid. One cc, or cubic centimeter, is the same amount as 1mL. When selecting a syringe, make sure the amount of medicine or fluid you need to draw up will fit into the syringe (don’t use a 1mL syringe when you need to draw up 2mL, for example).

Needles are labeled a little differently. The packaging will have a number, then a "G," and 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 Type of Needle and Syringe Do You Need?

The type of syringe and needle you need depends on the medication you've been prescribed. Based on the medication, your doctor or pharmacist will let you know the syringe and needle measurements you need.

If not, or if you don't recall, ask. Generally speaking, here is 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 inches 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 or 22 G needles that are an inch or an inch-and-a-half-long are usually appropriate for this type of injection. If you are thin, with very little fatty tissue, you can use the inch-long needle. If you are on the heavier side, you may need to use the inch-and-a-half-long needle.

If you aren't sure what type of injections you need or what needle or syringe size your doctor recommended, call your physician or pharmacist and ask. Using the right equipment will make the process easier and safer. 

Common Questions Fact Sheet. Village Fertility Pharmacy. 

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