Hypodermic needles
Separate needles for drawing and injecting, colour coded to the ISO standard so the gauge is readable across a bench at a glance.
Reading a needle
Two numbers describe a needle and they do different jobs. Gauge is the outer diameter and the scale runs backwards, so 25G is finer than 23G. Length decides the layer you land in: under the skin, or through it into muscle.
The hub colour follows ISO 6009, so 23G is blue and 25G is orange across every manufacturer that follows it. Manufacturers occasionally differ, so read the carton rather than trusting the colour alone. Our needle gauge chart lists every gauge with its outer diameter in millimetres.
Intramuscular and subcutaneous
An intramuscular injection has to clear skin and fat to reach muscle, which is why 23G to 25G at one inch to one and a half is the usual range. Too short and it goes into fat instead of muscle; the right length depends on the site and on the person.
Anything under the skin wants shorter and finer. If you are drawing from a vial and injecting with the same needle you are blunting it on the stopper, so draw up with an 18G and swap.
Everything on the box, before you buy.
The incumbents make you register to see a price. The batch and the expiry you are shipped are the ones printed here.
Questions about hypodermic needles
If yours is not here, the contact form routes to the person who can answer it.
