What Are the Different Syringe Sizes?

A syringe is a plastic or glass cylinder that contains a plunger that goes in one end and typically has a needle attached to the other. The term "syringe" can refer either to all three components — the cylinder, plunder, and needle — or just to the cylinder portion. Syringe sizes are indicated in milliliters and can range from 0.25 ml up to 450 ml. They also can be stated in cubic centimeters, where 1 cc is the approximate equivalent of 1 mL. These numbers indicate the volume of liquid that the cylinder is able to hold.

When referring to the unit as a whole, syringe sizes also might be given for the needle portion of the syringe because the size of the cylinder is often used to determine the size of the needle that will be attached to it. The needles themselves are categorized by length as well as the needle's gauge, indicating the overall thickness of the needle. Contrary to most measurement systems, the higher the needle's gauge, the smaller it actually is.

Insulin syringes, for example, are found in three common sizes: 1 cc, 1/2 cc, and 3/10 cc. The correct size syringe to use is determined by the average size of the dose of insulin that the patient administers. An insulin syringe also can be categorized by how many units of insulin it is designed to hold. Each mL or cc contains 100 units of insulin. A 3/10 cc syringe will hold up to 30 units of insulin, and a 1 cc syringe will hold up to 100 units of insulin.

There are other types of syringes, however, that do not include a needle as a component of their design. These include oral syringes, which most often are used to dispense liquids to babies or small children. Oral syringes differ from standard syringes only because of their tapered tip in place of a needle, so the same sizes are used to indicate how much liquid can be contained within the cylinder.

The final category of syringe contains neither a needle, a plunger or even a cylinder, and they are designed to clear wax and mucous from ear and nasal passages. Their lack of a cylinder means that both ear and nasal syringes are not categorized by standard syringe sizes at all. Unlike injection and oral syringes, this type are created in a bulbous design, comprised of a thin, rubber-like material and tapered to a rounded tip on one end. Ear and nasal syringes are typically found in one standard size, usually about 2 to 3 ounces (57 to 85 ml) in volume.

The smallest syringes on the market are created for microinjection used in scientific research done on very small animals such as rodents. It is necessary to use a very low volume syringe for these experiments to control dosage and to conform to the use of very small needles. Needles used for human subjects would damage the tissue and organs of small animals.

Whereas syringes used on humans have volumes that are measured in milliliters, syringes used for microinjections are so small that their volume is measured in microliters. These syringes fit needles as small as 36-gauge tips which are the smallest needles in existence today. They are only 2.5mm long to avoid over-penetration.

There is no commonly used average size when it comes to syringes. The size of the syringe is affected by several factors:

Syringes that are used for injections can vary in volume from 1ml to 6ml. The syringe size will typically be chosen depending on the volume of medication it needs to hold. These smaller syringes have a higher level of pressure allowing them to deliver medication subcutaneously or intramuscularly.

Syringes used with tubing are larger than those used for injections. These syringes typically have a volume of 10ml to 12ml. The higher volume potential and the lower pressure delivery make these syringes the best choice for central lines and catheters.

These are the largest syringes with volumes as high as 20ml to 70ml. Irrigation syringes can deliver high volumes of liquid with a pressure low enough to remove debris without causing damage to tissue or tubing.

The most common use of an irrigation syringe is in the flushing of debris from wounds to avoid infection. These syringes are often included in first aid kits to help with wound care. Irrigation syringes are also used to flush tubing used for catheters to clear them of blockages.

The size of insulin syringes varies because the dosage of insulin needed for an individual will be unique. It is best to choose a syringe with a volume as close to the dosage of insulin as possible. This will help to avoid accidental overdoses.

Insulin syringes can be purchased with or without needles. Those that come with needles, tend to come with very fine tips. As diabetics need to take insulin continuously, finer tips can help alleviate the pain and damage of repeated injections.

Syringes that come with attached needles can have a variety of tips. Some of the most common are: