What Is a Luer Lock?

Mary McMahon
Mary McMahon
Mary McMahon
Mary McMahon
An IV cannula with a three-way stopcock and Luer lock.
An IV cannula with a three-way stopcock and Luer lock.

A Luer lock is a screw connection on a syringe that creates a leak-free seal. Care providers can connect needles, tubing, and other equipment to the lock to perform various activities involved in patient care. This fitting is standardized, with all medical supply companies producing designs to the same specification. Standardization permits the interchangeable use of various medical devices, allowing care providers to choose the best equipment for a given task without worrying about compatibility.

A luer lock may be used during a blood draw.
A luer lock may be used during a blood draw.

The basic design was developed in the 19th century, originally as a seal for glass bottles. Applications for syringes led to adoption of the Luer lock by medical professionals. Instead of pulling fittings on and off a syringe, care providers use the screw mechanism. This reduces the risk that the fittings will fall off, and creates a tight seal with a minimum risk of leakage. For patient and provider safety, controlling leaks can be important.

Syringe filters typically have Luer Lock fittings.
Syringe filters typically have Luer Lock fittings.

Syringes for injection can come with a Luer lock. Care providers can switch needles at the lock for procedures like drawing up an injection, then getting a fresh needle to reduce pain for the patient. They can select the optimal needle size, given the type of injection and the patient, and make sure it is securely fastened. Conversely, Luer locks can also be used in activities like blood draws, where they can hold a needle or be connected with a cannula or intravenous line to pull several tubes of blood.

Tubing for intravenous drips, subcutaenous fluids, and other procedures can latch onto a Luer lock device. In this case, the needle can be connected to the tubing and inserted, or it may be left in place to provide continuous catheter access. When no one needs access, the Luer lock can be capped to minimize the chance of infection. Minimal leakage can be important with a variety of medical products, and also helps keep the working environment clean.

Syringes and other accessories with a Luer lock fitting usually indicate this on their packaging, and the lock may be visible in clear packages. There are several designs on the market and it is important to make sure the right one is in use. It is possible to special order medical supplies with this feature if a patient or care provider wants to use Luer lock needles and equipment. Suppliers may need several days to locate and ship unusual items, but may be able to provide service within a week in many cases.

Luer Lock vs Luer Slip

While both Luer locks and Luer slips are similar components of medical syringes and sound relatively like the same thing, they do not refer to the exact same device. Both the Luer lock and Luer slip portions of syringes allow syringe tips to be efficiently changed and provide leak-proof seals between the two main portions of a syringe, but they do so in different ways. The biggest difference between a Luer lock and a Luer slip is in how they securely attach the ending component of a syringe to the rest of the syringe device. Luer locks have to be fully screwed in to create the necessary seal while Luer slips require being pushed in first and then need only a quarter turn to create a similar seal.

Since both options have the same desired result, it mostly comes down to personal experience and preference when deciding which kind to use. Many choose Luer locks over Luer slips as they find them to be more secure and harder to attach incorrectly. Others prefer to use the Luer slip syringe type, as they find them more efficient to use once they figure out what a secure slip connection feels like and learn to replicate it with every use.

Are All Luer Locks the Same Size?

Another Luer lock quality that many people appreciate is that while there are different sizes and types, they generally follow universal standards which make pairing the right lock with the right syringe an easier task. The best way to ensure a tight fit is to match the size and type of Luer lock to each syringe. Different manufacturing companies might make different sizes and types of Luer syringes as well, so it is always best to pair syringes and Luer locks that are designed and produced by the same manufacturer.

Not only are there different sizes of Luer locks, but there are also specific types of Luer locks designed for specific syringe attachments. For instance, the Luer lock that attaches a needle will be a different Luer lock than the one that is used for attaching catheter tubing. One other major difference is whether it is considered a male or a female connector. Male connectors tend to have a piece sticking out that attaches to the main syringe piece, whereas female connectors have a completely open end to attach them to the syringe.

How To Use a Luer Lock Syringe

No matter which kind, many people find Luer syringes easier and more efficient to use than non-Luer syringes. One of the biggest appeals is the ability to use the same syringe for multiple patients or uses by simply changing out the end piece rather than the entire syringe every time. This tends to cut down on costs, time, and effort. The most important part is ensuring that the locking mechanism connects properly. Luer locks have to be precisely screwed on so that the tread completely interlocks and Luer slips require the proper push and turn combination to enact the desired and required leak-proof seal each time. After use, it is also important to properly clean, sanitize, and dispose of the different syringe components to maintain a safe and hygienic environment.

Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a TheHealthBoard researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a TheHealthBoard researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

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    • An IV cannula with a three-way stopcock and Luer lock.
      By: Aleksandrs Jermakovi
      An IV cannula with a three-way stopcock and Luer lock.
    • A luer lock may be used during a blood draw.
      By: Tim UR
      A luer lock may be used during a blood draw.
    • Syringe filters typically have Luer Lock fittings.
      By: KALISTE A
      Syringe filters typically have Luer Lock fittings.