Insulin pens (like the one shown here) come in two styles: disposable (one-time use) and reusable (many times). Also, each pen is specially designed and manufactured to hold a particular type or mixture of insulin.
An insulin pen.
Pen needles come in varying lengths and diameters, just like syringe needles. Screw on a new needle each time you inject insulin with your pen (needles can carry viruses or bacteria). Follow the instructions on your insulin pen to prime it. Then follow the dosing instructions from your healthcare provider, as well the instructions included with your pen.
Just like storing a vial of insulin, protect your insulin pen from extreme temperatures. You can keep pens you’re currently using at room temperature and store unused pens in the refrigerator. Dispose of used needles in a safe container according to the package instructions.