Pen needles vs hypodermic needles

Although both are used to administer injectable medication, pen needles and hypodermic needles are designed for different purposes. They differ in how they connect to the medication, their intended use, and the types of injections they are used for. Understanding these differences will help you choose the correct product and use your medication safely.

Pen needles and hypodermic needles serve different purposes. Pen needles are designed exclusively for injection pens and are commonly used for insulin and GLP-1 medications. Hypodermic needles attach to syringes and are suitable for a wide variety of medical procedures, including drawing medication from vials and administering subcutaneous or intramuscular injections.

What are pen needles?

Pen needles are designed specifically for use with injection pens. Instead of attaching to a syringe, they screw or click directly onto a compatible medication pen. Many modern injectable medications are supplied in prefilled pens, making administration simple and convenient. Pen needles are commonly used for:

• Insulin therapy
• GLP-1 medications such as semaglutide and tirzepatide
• Growth hormone treatments
• Other medications supplied in injection pens

Pen needles are available in different lengths and gauges, with 4 mm and 5 mm being among the most commonly used sizes. They are intended for subcutaneous injections, meaning the medication is delivered into the fatty tissue just beneath the skin. After each injection, the pen needle should be removed and safely disposed of before a new sterile needle is used for the next injection.

What are hypodermic needles?

Hypodermic needles are designed to attach to a syringe, usually through a Luer Slip or Luer Lock connection. Unlike pen needles, hypodermic needles are highly versatile and can be used for many medical applications. Depending on the medication and procedure, they may be used for:

• Drawing medication from a vial or ampoule
• Subcutaneous injections
• Intramuscular injections
• Medical and laboratory procedures
• Veterinary applications

Hypodermic needles are available in a much wider range of lengths and gauges than pen needles, allowing healthcare professionals to select the most appropriate combination for each situation.

Which one should you use?

The choice depends entirely on how your medication is supplied. If your medication comes in a prefilled injection pen, you will need a compatible pen needle. These products are specifically designed to work together and cannot be replaced with standard hypodermic needles.

If your medication is supplied in a vial or ampoule, you will typically need a syringe fitted with a compatible hypodermic needle. In some cases, one needle is used to draw up the medication and a new sterile needle is attached before the injection is given.