What Is a Reusable Insulin Pen?
A reusable insulin pen is an injection device that holds a replaceable 3ml insulin cartridge. You keep the pen body and swap out the cartridge when it runs empty.
Standard 3ml glass cartridge - replace when empty
One pen can last for years, replacing hundreds of disposable syringes.
A reusable insulin pen with dose dial and cartridge compartment
Reusable pens let you dial your dose with a knob on the end — no drawing insulin from a vial with a syringe. Most pens deliver between 0.5 and 60 units per injection, adjustable in half-unit or one-unit steps depending on the model.
Step-by-Step: How to Use a Reusable Insulin Pen
1. Wash Your Hands
Use soap and warm water. Dry thoroughly. Clean hands reduce the risk of infection at the injection site.
2. Check the Pen and Cartridge
Remove the pen cap. Look at the insulin cartridge through the window. Check the label — make sure it is the correct insulin type for your prescription. If the cartridge is cracked, cloudy (when it should be clear), or past its expiration date, replace it.
For cloudy insulins (NPH, premixed): gently roll the pen between your palms 10 times, then tip it up and down 10 times. Do not shake.
3. Attach a New Needle
Peel the protective seal off a new pen needle. Screw it straight onto the pen until snug. Remove the outer cap and set it aside — you will need it to remove the needle later. Remove the inner cap and discard it.
Use a fresh needle for every injection. Reusing needles dulls the tip, makes injections more painful, and increases infection risk.
4. Prime the Pen
Dial 2 units on the dose knob. Hold the pen with the needle pointing up. Tap the cartridge holder gently to move air bubbles to the top. Press the injection button all the way. Watch for a stream or drop of insulin at the needle tip. If nothing appears, repeat. Prime before every injection to ensure accurate dosing.
5. Dial Your Dose
Turn the dose knob until the number in the window matches your prescribed dose. Most pens click with each unit. If you overshoot, dial back — most pens allow correction in both directions.
Check the cartridge window: you cannot dial more units than what remains in the cartridge.
6. Choose an Injection Site
Common sites: abdomen (fastest absorption), upper thigh, back of the upper arm, or buttock. Rotate sites with each injection — using the same spot repeatedly can cause hard lumps (lipohypertrophy) that affect absorption.
Clean the area with alcohol if instructed by your doctor. Let it dry before injecting to reduce stinging.
7. Inject
Insert the needle at a 90-degree angle without pinching unless you are very lean or using a needle longer than 6mm. Press the injection button down fully. Hold it for a slow count of 10 before removing the needle. This ensures the full dose is delivered.
8. Remove and Dispose of the Needle
Use the outer cap you saved earlier to unscrew the needle. Drop it into a sharps container (FDA sharps disposal guide). Never leave a needle attached to the pen between injections — air, bacteria, and temperature changes can affect the cartridge.
Reusable Pen vs Disposable Pen
| Reusable Pen | Disposable Pen | |
|---|---|---|
| Cost over time | Lower — buy the pen once, replace only cartridges | Higher — replace the entire pen each time |
| Environmental impact | Less plastic waste | More plastic waste |
| Maintenance | Wipe body with alcohol periodically | None — dispose after use |
| Travel | Carry pen + spare cartridges | Carry spare pens |
| Dose range | Typically 0.5–60 units | Varies by model |
Auto-injector - one-click delivery for prefilled syringes
Common Questions
Can I use the same pen for different insulins?
No. Each pen should be dedicated to one type of insulin. Mixing insulin types in the same cartridge can cause dangerous dosing errors. Label your pens if you use more than one.
How long does a reusable pen last?
With proper care, a metal reusable pen can last several years. Plastic-body pens typically last 1–2 years with daily use. Replace the pen if the dose dial becomes stiff, the cartridge holder cracks, or the injection button feels loose.
Do I need a prescription to buy a reusable insulin pen?
In most countries, the pen device itself does not require a prescription — it is the insulin cartridges that require one. Check your local regulations. Faxne ships pen devices without requiring a prescription.
What size needle should I use?
4mm needles are recommended for most adults and children regardless of body type. They are long enough to reach subcutaneous tissue without hitting muscle. 5mm needles may be appropriate for some individuals. Needles longer than 6mm are generally not recommended.
Can I fly with a reusable insulin pen?
Yes. Keep your pen and cartridges in your carry-on bag. Cabin temperature is safe for insulin. Do not put insulin in checked luggage — cargo holds can freeze. Carry a letter from your doctor if traveling internationally.
Tips for First-Time Users
- Practice dialing and priming with a used cartridge first — it builds confidence without wasting insulin
- Keep a spare pen as backup in case yours is lost or damaged
- Store unopened cartridges in the refrigerator (2–8 deg C)
- Once opened, most cartridges can be kept at room temperature for 28 days
- Write the date on the cartridge label when you first use it
This article references guidelines from the CDC Diabetes Division. This article is for educational purposes. Always follow your healthcare provider's instructions for insulin use and dosing. If you experience unexplained high or low blood sugar readings, contact your doctor.
Explore Faxne products: Reusable Injection Pens | Glass Cartridges | TCM Herbs