What Is a Syringe? Types, Parts & Uses

Last verified: October 6, 2026. A syringe is a simple hand-operated device that draws in, holds, measures, and pushes out a controlled amount of liquid or gas. It is one of the most common single-use items in healthcare, and it is just as common in research laboratories. This guide explains what a syringe is, what its parts do, the main types, how it differs from related tools, and why it matters to the people who buy and manage supplies.

What Is a Syringe?

A syringe is a hollow cylinder (the barrel) fitted with a sliding plunger. Pulling the plunger back creates suction that draws fluid into the barrel through an opening at the tip; pushing the plunger forward pushes the fluid back out. Markings printed along the barrel let the user read how much fluid has been drawn up. Because the same simple mechanism works for liquids of many thicknesses and for air, syringes are used to measure, transfer, mix, and deliver fluids in a very wide range of settings.

A syringe is often confused with the needle that may be attached to it. They are separate items. The syringe is the measuring and pushing part; a needle, a blunt tip, a cap, or a length of tubing is what connects the syringe to wherever the fluid is going. Many syringes are sold without any needle at all.

Why It Exists: The Problem a Syringe Solves

Moving a small, known amount of fluid from one place to another by hand is surprisingly hard. Pouring is imprecise, and open containers invite spills and contamination. A syringe solves this by enclosing the fluid in a sealed, graduated chamber and giving the user fine control over how much is drawn in and how fast it is pushed out. The sealed design also helps keep the contents separate from the surrounding environment, which matters when the fluid must stay clean, or when it is hazardous and must be kept away from the user.

The Main Parts of a Syringe

• Barrel — the clear cylinder that holds the fluid. It is usually transparent so the user can see the contents and any air bubbles, and it carries the volume scale.
• Plunger — the rod the user pushes and pulls. Its inner end carries a sealing piece that slides against the barrel wall.
• Stopper (gasket) — the flexible seal at the end of the plunger. It keeps fluid from leaking past the plunger and is what the volume reading is aligned to.
• Tip (hub) — the opening at the front where a needle, cap, or tubing attaches. The shape of this connection is a key part of compatibility.
• Flange (finger grip) — the flat wings at the open end of the barrel that give fingers something to brace against while pressing the plunger.

Who Uses a Syringe

Nurses, physicians, pharmacists, dentists, veterinarians, and many other clinical staff use syringes daily to measure and deliver medications and to draw samples. Patients and caregivers use them at home for prescribed injections and for measuring liquid medicine. In research, laboratory staff use syringes for transferring reagents, loading analytical instruments, filtering small volumes of liquid through a syringe filter, and dosing animals under approved protocols. Facilities teams and hobbyists even use large syringes for non-medical jobs such as applying lubricants or adhesives, which is a reminder that the device is really just a precise fluid-handling tool.

Types of Syringes

Syringes are sorted in several overlapping ways. Understanding the categories makes product descriptions much easier to read.

By tip connection

• Slip tip — the needle or tubing simply pushes onto a smooth, tapered tip and is held by friction. It is quick to attach and remove.
• Locking tip — the tip has a threaded collar, so a compatible needle or fitting is twisted on and locked in place. This reduces the chance of accidental disconnection, which is useful with thick fluids or higher pressure.
• Eccentric tip — the opening sits off to one side of the barrel instead of in the center, which lets a needle lie nearly parallel to a surface. It is used where a shallow angle is helpful.
• Catheter tip — a longer, tapered tip designed to connect to catheters, feeding tubes, and irrigation lines rather than needles.

By intended use

• General-purpose syringes in a range of sizes for everyday measuring and delivery.
• Insulin-style syringes, which are graduated in a way that suits that particular use. See the CASRAI guide to insulin syringe sizing, needle gauge, and volume selection for more detail.
• Oral syringes, designed for measuring liquid medicine to be taken by mouth, often with tips that do not fit a needle.
• Irrigation syringes, larger and often bulb-like or wide-tipped, for rinsing wounds or flushing lines. The bulb syringe is a familiar relative.
• Prefilled syringes, which arrive already loaded with a measured product.
• Safety syringes, which add a shield or retracting feature intended to reduce the risk of needlestick injury after use.

By material

Most syringes today are plastic and meant for single use. Glass syringes also exist, mainly in laboratory work, where chemical resistance or very precise volumes matter and the device can be cleaned and reused according to the lab’s procedures.

How a Syringe Differs from Related Tools

• Syringe vs. pipette — both move liquid, but a pipette is a laboratory tool built for very small, highly repeatable volumes and usually uses disposable tips. A syringe handles a broader range of volumes and is the usual choice for delivery into a patient, a line, or an instrument port.
• Syringe vs. needle — the needle is only the narrow hollow tube attached to the tip. A common specialized example is the butterfly needle, which combines a short needle with flexible tubing.
• Syringe vs. IV catheter or IV bag — an IV catheter is a small flexible tube left in a vein, and an IV bag is a larger reservoir of fluid. A syringe is often used alongside these, for example to deliver a measured amount through an access port, but it is a different device.
• Syringe vs. dropper — a dropper delivers approximate drops with a squeeze bulb; a syringe offers a measured, graduated volume.

Practical Relevance for Research Administration and Procurement

Syringes are a high-volume consumable, so small decisions about specification add up across a budget year. A few points are worth knowing:

• Specification matters. Size, tip type, material, whether a needle is included, and whether the syringe is sterile or non-sterile all affect compatibility. Ordering the wrong tip connection is a common and avoidable mistake. The CASRAI guide to sterile vs. non-sterile purchasing covers that distinction.
• Sharps handling. Syringes with attached needles are sharps. Facilities typically need appropriate sharps containers and a disposal arrangement, and the cost and logistics of that should be planned alongside the purchase.
• Safety features. Some institutions specify safety-engineered syringes as policy. Procurement staff should check the local requirement before standardizing on a product.
• Controlled use. In research settings, syringes and needles may be subject to institutional controls on purchase and storage. Check with your environmental health and safety office.
• Compatibility with the work. Some chemicals can degrade certain plastics or rubber stoppers, and some sensitive assays are affected by what leaches from a syringe. Labs usually confirm that a syringe is suitable for their specific application.

Common Misconceptions

A few ideas about syringes come up repeatedly. The first is that a syringe always means an injection. In reality, many syringes never go near a needle: they measure oral liquids, rinse equipment, or load laboratory instruments. The second is that a larger syringe is automatically better. A syringe is most accurate when the volume being measured is a sensible fraction of its capacity, so a small volume is usually better measured in a smaller barrel with finer markings. The third is that all tips are interchangeable. Slip, locking, and catheter-style connections are made for different purposes, and a mismatch can cause leaks or disconnection.

Finally, people sometimes assume that a clear plastic barrel means the contents are visible and safe to judge by eye. Reading the volume correctly depends on lining up the scale with the correct part of the stopper, and manufacturers show how to do this in their instructions. Users in training environments often practice this reading step because small errors can change the amount measured.

The Short Version

A syringe is a barrel-and-plunger device that measures and moves fluid in a controlled, sealed way. Its tip connection, size, material, and sterility determine whether it suits a given job. It is distinct from the needle that may be attached to it, from a pipette used for tiny laboratory volumes, and from the IV equipment it is often used with.

This page offers general information only. It is not clinical or safety training. Always follow your institution’s procedures and the manufacturer’s instructions for any specific product.

Frequently Asked Questions

What is a syringe used for?

A syringe is used to draw up, measure, and deliver liquids or gases. In healthcare that means giving medications and collecting samples; in laboratories it means transferring reagents, loading instruments, and filtering small volumes.

Is a syringe the same as a needle?

No. The syringe is the barrel and plunger that hold and push fluid. A needle is a separate hollow tube that may be attached to the tip. Many syringes are used with no needle at all, such as oral syringes.

What is the difference between a slip tip and a locking tip?

A slip tip holds a needle or tubing by friction alone, so it attaches and detaches easily. A locking tip uses a threaded collar to twist the attachment into place, which makes accidental disconnection less likely.

Can syringes be reused?

Most plastic syringes are made and sold for single use and should be discarded after use according to local waste procedures. Some glass laboratory syringes are designed to be cleaned and reused, but only following the lab’s own validated procedures and the manufacturer’s guidance.

Why are syringes marked in different units?

Different uses call for different scales. Some syringes are marked in milliliters, others in units specific to a particular purpose. Checking the scale printed on the barrel against the intended use is part of choosing the right product.

How is a syringe different from a pipette?

A pipette is a laboratory instrument for measuring very small liquid volumes with high repeatability, usually with replaceable tips. A syringe covers a wider range of volumes and is generally used when fluid needs to be delivered into something, such as a patient, a line, or an instrument.