Updated: Nov 2, 2022
Choosing the right size needle and syringe is critical in order to get the correct dose of medicine, inject it properly, and minimize the patient's pain. With so many options and variations in sizing, how can you be sure you are using the correct item for your application? We've put together a comprehensive and detailed breakdown to help you choose the best option.
Syringes are labeled based on how much liquid they can hold. There are two ways syringe capacity can be measured.
Syringe Capacity Measurement
Cubic centimeters (cc) for the volume of solids
Milliliters (mL) for liquid volume
Example: 1 cc is equal to 1 mL.
Different size syringes, are commonly used to administer different types of medications and drugs.
For example, if a certain drug requires 3 mL of injection, it is recommended to use a syringe that holds precisely 3 mL. If you use a syringe that holds only 2 mL, you would have to inject yourself more than once (which would cause unnecessary pain) to reach the required amount (3mL).
This applies the other way around as well. If you use a syringe that holds 15 mL, it will be harder to see the mL markings and measure 3 mL accurately. This means you could mistakenly end up giving yourself too little or too much medication.
There are two common forms of needle measurement, by diameter and length.
Commonly known as "G", this represents the gauge of the needle. The lower the gauge is, the wider the needle.
The second number indicates the length of the needle, in inches.
For example, a 25 G x 1" needle has a gauge of 25 and a is one inch in length.
If you need to inject yourself with a small amount of medication, studies have shown it to be less painful to use a thin, or high-gauge needle over against a wider, lower-gauge needle.
For larger amounts of injections, a wider needle with a lower gauge is often a better choice. While it might be more painful, a wide, low-gauge needle will complete the injection more quickly than a thin, high-gauge needle.
One of the factors contributing to choosing the correct needle length is most often a person's size and weight. Example: A small child would require a shorter needle than a large adult would. It is also critical that the healthcare personnel administering the injection takes into account the level of body fat the needle has to go through. While a thin person might be able to use a one inch long needle, a heavier person might require a needle that is an one and a half inch long.
Finding the right combination of gauge and length is very important in determining the right product.
There are two main types of injections, commonly used to inject various medications:
Subcutaneous Injections & Intramuscular Injections
Some medications can be absorbed superficially or directly underneath the skin, while others must be injected into the muscle (deeper).
Subcutaneous injections: These injections go into the fatty tissue just below the skin. Since these are relatively shallow shots, the needle required is small and short—typically one-half to five-eighths of an inch long with a gauge of 25 to 30.
Intramuscular injections: This type is a much deeper injection than just the subcutaneous layer of skin, these go directly into a muscle. The needle used for intramuscular injections must be thicker and longer in order to effectively reach that area. Clinicians have found that using 20 or 22 G needles that are one inch or one and a half inch in length work best in this application.
Proper vaccine administration is critical to ensure that vaccination is safe and effective. CDC recommends that all health care personnel who administer vaccines receive comprehensive, competency-based training on vaccine administration policies and procedures BEFORE administering vaccines. Comprehensive, skills-based training should be integrated into existing staff education programs such as new staff orientation and annual education requirements.
For specifics on the CDC's recommended Needle & Syringe sizes, visit here.
To learn more about Vaccine Administration, visit here.
For a specific guide to the Pfizer-BioNtech COVID Vaccine Administration, visit here.