What to Do If Your Insulin Pen Is Not Working (From Real Experience + Safe Troubleshooting Guide)

I still remember the first time an insulin pen stopped working on me — and honestly, it’s one of those moments you don’t forget.

It was a completely normal day, nothing unusual, and suddenly when I tried to inject, the pen just… didn’t respond. The button felt strange, there was resistance where there shouldn’t be, and no insulin came out. For a few seconds, I just froze there, holding the pen and wondering:

👉 “Did I just take my dose… or not?”

That moment of uncertainty is incredibly stressful, because insulin isn’t something you can “guess” with. Your blood sugar depends on it being delivered correctly, at the right time, in the right amount. And when something goes wrong, even something small, it immediately creates doubt.

Insulin pen problems are actually more common than people think. They don’t necessarily mean something is seriously wrong, but they do require the right reaction in the moment.

In this guide, I’ll walk you through:

• Why insulin pens stop working (including the less obvious reasons)
• Exactly what I would do step by step when it happens
• Practical, experience-based tips to avoid this situation in the future

If your insulin pen is not working, jammed, or not injecting insulin properly, understanding the cause quickly is essential to avoid dosing errors.

⚠️ BUT FIRST, A SAFETY REMINDER!

Before we go into troubleshooting your jammed insulin pen, there’s one key point that cannot be ignored: If your insulin pen is not working properly, you cannot be completely sure how much insulin has been delivered.

And that uncertainty matters. Because:

• Too little insulin may lead to rising blood sugar levels (hyperglycemia)
• Repeating a dose without being sure may increase the risk of hypoglycemia

This is why health authorities like the American Diabetes Association, consistently recommend caution when something feels off with your insulin delivery device.

👉 If you’re unsure, the safest option is always to stop, check, and seek professional advice.

How Insulin Pens Work (And Why Understanding This Changes Everything)

One thing that helped me a lot over time was simply understanding how insulin pens actually work. Because when something breaks or doesn’t work, it stops feeling random — it becomes logical.

Insulin pens are, in most cases, purely mechanical devices. There’s no complex electronics inside. Instead, they rely on a very simple system:

• A cartridge that contains insulin
• A dial that allows you to select your dose
• A plunger mechanism that pushes insulin through the needle

That’s it. Which means:

👉 When a pen “fails,” it’s almost always due to a physical issue — not something mysterious.

And once you realize that, troubleshooting becomes much calmer and more structured.

The First Thing I Do When an Insulin Pen Doesn’t Work

Over time, I’ve developed a reflex. Instead of panicking, I mentally go through a simple checklist:

👉 “Is it empty, blocked, or damaged?”

Because in the vast majority of cases, one of these three explains everything. So, let’s go deeper into each of them — not just theoretically, but from real-life situations.

1. “Wait… is my pen just empty?”

This might seem obvious, but in reality, it’s one of the most frequent causes of insulin pen issues.

Sometimes the cartridge still looks like it contains insulin — you can see liquid inside — but there isn’t actually enough left for the mechanism to function properly. The pressure needed to push insulin through the system simply isn’t there anymore.

I’ve seen people (and honestly, I’ve done it myself once) try to “get one last dose” out of a pen. That’s usually when the dial stops working or the injection button becomes hard to press.

👉 That’s often mistaken for a malfunction — when it’s actually just an empty or nearly empty cartridge.

✔️ What I do now: If there’s any doubt, I don’t try to push it further. I switch to a new pen immediately. Because trying to force those last units can create more problems than it solves.

2. The needle — the most underestimated issue

If there’s one thing I’ve learned, it's that blocked insulin needles are incredibly common.

Most insulin pen problems are actually needle problems.

Insulin pen needles become blocked due to:

• Insulin drying and crystallizing at the tip
• Tiny particles or debris
• Slight bending of the needle
• Reuse (which happens more often than recommended in real life)

I’ve seen situations where a pen seemed jammed — no insulin coming out, strange resistance — and simply changing the needle fixed everything instantly.

✔️ What I always do now: Before assuming anything else, I change the needle.

This aligns with recommendations from the American Diabetes Association, which advises using a new needle for each injection to ensure proper flow and reduce complications.

3. Priming Your Insulin Pen — the step people skip (but shouldn’t)

Let’s be honest: priming your insulin pen is one of the most commonly skipped steps, especially when you’re busy or in a hurry. But skipping it can create real problems.

Without priming:

• Air can remain inside the system
• Insulin may not flow properly
• You might inject little or no insulin at all due to air bubbles in your pen

It happened to me to think my insulin pen wass faulty, when in reality, it just wasn’t primed.

✔️ What I personally do every single time now:

• Dial 1–2 units
• Press the button
• Wait until I clearly see a drop

It takes a few seconds, but it removes a huge amount of uncertainty.

4. When something feels “off” — trust that instinct

This is something you don’t read often, but it’s incredibly important. Sometimes, the insulin pen doesn’t visibly look broken.

But it feels different:

• Slightly harder to press
• Less smooth than usual
• Not quite “normal”

Every time I’ve ignored that feeling, it turned out something was wrong.

Possible reasons include:

• Internal damage from being dropped
• Pressure from being carried in a bag
• Exposure to heat or cold- storage temperature extremes can affect insulin stability and potentially impact delivery systems.

✔️ My rule now: If something feels unusual, I don’t take the risk — I replace the pen.

From experience, using an insulin travel cooler can help prevent many temperature-related issues — especially when traveling.

Step-by-Step: What I Actually Do if My Insulin Pen Is Not Working

Here’s the exact process I follow now, calmly and systematically:

• Step 1: Pause and don’t rush

This might sound simple, but it’s essential. Most mistakes happen when you’re stressed or rushing.

• Step 2: Replace the needle immediately

Even if it looks fine. This alone solves a surprising number of issues.

• Step 3: Prime the pen properly

Hold the pen upright. Dial 1–2 units and press the button to inject in the air. Wait until you clearly see insulin at the tip of the needle. 

• Step 4: Check the insulin itself

Is there enough insulin left for my full dose? Does it look normal (clear, no particles, no discoloration)? If anything seems off → use a new pen!

• Step 5: Make a decision quickly

If the pen still doesn’t behave normally: I stop using it. No hesitation, no forcing.

A Very Common (and Risky) Situation

Here’s something I’ve heard many times for our blog readers. Someone injects, nothing happens, so they immediately try again.

But later: 
👉 Blood sugar drops unexpectedly

Why?

Because:

• The first injection may have partially worked
• The second dose added on top

This is exactly why guidance from organizations and diabetes centers emphasizes not repeating injections unless you’re sure of what happened.

Related: The Ultimate Guide to Traveling with Insulin: How to Keep It Refrigerated and Cool on the Go

Why Insulin Pens Often Fail During Travel

If there’s one situation where issues appear more frequently, it’s during travel. And it makes sense when you think about it.

Travel involves:

• Temperature changes
• Movement and pressure
• Disrupted routines
• Fatigue and distraction

I’ve seen problems happen:

• After leaving a pen in a warm car
• During long flights
• On busy travel days

👉 Heat, in particular, is a major factor.

Insulin exposed to temperatures above recommended levels can lose effectiveness, and in some cases, it may also affect how the pen performs.

How I Prevent These Problems Now

After enough of these situations, a few habits made a huge difference:

• I always carry a backup pen
• I never skip priming
• I change needles regularly
• I pay attention to storage conditions
• I always, always carry my insulin pens in medical-grade travel coolers. 

👉 Especially in summer or when traveling

Because the reality is that most insulin pen issues are preventable with small, consistent habits.

Related: What happens if insulin gets too warm

More Questions About Jammed Insulin Pens?

• Can you reset an insulin pen?

No — standard insulin pens are mechanical devices and do not have a reset function. However, priming can often restore proper flow.

• Can you dial back a dose?

Most insulin pens allow you to dial backward safely. Always double-check your dose before injecting.

• Should you try to fix a faulty insulin pen?

No. A malfunctioning pen can deliver inaccurate doses, which can be dangerous. Replacing it is always the safer option.

If your insulin pen is faulty, you can contact the manufacturer directly for support or replacement:

Here are some contacts in the USA that can be helpful to request replacement of the most commonly prescribed insulin pens: 

• 👉 Lilly Diabetes Solutions Center (U.S. support line):
  📞 +1-833-808-1234
• 👉 Sanofi Customer Service
• 👉 Novo Nordisk U.S. Contact & Support

Final Thoughts

If your insulin pen stops working, it can feel stressful — especially in the moment. But in most cases, the cause is simple:

• A blocked needle
• A priming issue
• Or a nearly empty cartridge

The key is to:

• Stay calm
• Follow a clear process
• Avoid forcing anything

And most importantly: If something doesn’t feel right, trust that instinct.

💬 Your Experience Matters! 

Have you ever had an insulin pen stop working — especially at the worst possible moment? Maybe while traveling, in the middle of a busy day, or when you didn’t have a backup nearby?

These situations can feel stressful and uncertain, but they’re more common than people think — and sharing real experiences can make a big difference for others.

👉 What happened in your case?
👉 How did you handle it?
👉 Did you find something that helped prevent it in the future?

Your experience could help someone else feel more prepared and less alone when it happens to them! Please share it in the comments below.