Insulin, EpiPens, and Nitroglycerin: What Happens When They Expire

When your insulin, EpiPen, or nitroglycerin passes its expiration date, it doesn’t just become less effective-it might stop working entirely. And in an emergency, that difference can mean the difference between life and death.

Why These Three Medications Are Different

Most pills and antibiotics can sit on a shelf for years after their expiration date and still work fine. A 2012 FDA study found that 90% of tested drugs retained full potency even 15 years past expiration. But insulin, epinephrine (in EpiPens), and nitroglycerin aren’t like those drugs. They’re unstable. They break down fast. And when they do, they don’t just lose a little strength-they can fail completely when you need them most.

Insulin is a protein. Protein degrades. Heat, light, and time all attack it. Once opened, most insulin types last only 28 to 42 days-even if the bottle says it’s good for another year. If you leave it in a hot car or a sunny bathroom, it can lose potency in hours. A 2023 case from Swedish Medical Center showed a patient developed diabetic ketoacidosis after using insulin that was just three months past its expiration date. They ended up in intensive care for three days.

Nitroglycerin is even worse. It’s a volatile chemical used to stop heart attacks by relaxing blood vessels. But it’s also incredibly sensitive to air, heat, and moisture. Once you open the bottle, it starts losing potency. A 2018 study in the Journal of Pharmaceutical Sciences found it loses about 20% of its strength in just 30 days. By six months past expiration, it may have almost none left. Baptist Health tracked patients who used expired nitroglycerin during chest pain: 78% needed emergency care because the medicine didn’t work. In contrast, only 22% of those using fresh nitroglycerin needed hospitalization.

EpiPens contain epinephrine, the only drug that can reverse a deadly allergic reaction. But epinephrine breaks down too. Mylan’s own data shows that even at the labeled expiration date, an EpiPen delivers only about 80% of the labeled dose. Six months after expiration, that drops below 50%. A 2021 study in the Annals of Allergy, Asthma & Immunology found expired EpiPens delivered only 52-68% of the needed dose a year past expiration. One Reddit user described a near-fatal bee sting where the expired EpiPen did nothing-emergency responders had to give three doses to save them.

What Happens When You Use Expired Insulin

If you’re diabetic and your insulin has expired, your blood sugar won’t just be a little off-it could go wildly out of control. One user on r/diabetes, u/InsulinWarrior, shared how their blood sugar spiked to 450 mg/dL and crashed to 50 mg/dL within hours after using insulin two months past expiration. They were hospitalized for two days. That’s not a fluke. Insulin doesn’t degrade slowly like a battery losing charge. It breaks down unpredictably. Sometimes it’s too weak. Sometimes it’s still active but inconsistent. That inconsistency is dangerous. Your body can’t adapt to random insulin doses. You risk ketoacidosis, coma, or death.

Unopened insulin should be refrigerated between 36°F and 46°F. Once opened, keep it at room temperature (below 86°F) and mark the date you opened it. Set a calendar alert for 28 days later. Don’t rely on the bottle’s expiration date after that. Even if it looks clear and feels fine, it’s no longer safe.

What Happens When You Use an Expired EpiPen

An EpiPen isn’t a backup. It’s your only shot. If you’re having anaphylaxis-swelling, trouble breathing, dropping blood pressure-you need full-strength epinephrine right now. Expired EpiPens might still deliver some drug. But not enough. And in an emergency, you don’t have time to wait for it to work.

The American College of Allergy, Asthma, and Immunology says using an expired EpiPen is better than nothing. But that’s not a recommendation-it’s a last resort. Their official guidance is: call 911 first, then use the expired device, then tell responders it was expired. Don’t delay calling for help because you’re waiting for the EpiPen to work. It might not.

Check your EpiPen every month. Look at the fluid inside. It should be clear and colorless. If it’s brown, cloudy, or has particles, throw it out-even if it’s months from expiration. Heat exposure, like leaving it in a car or a backpack in summer, can damage it faster than time alone.

What Happens When You Use Expired Nitroglycerin

Nitroglycerin doesn’t just expire-it evaporates. The tablets are packed in glass bottles with a cotton plug to limit air exposure. But once you open it, oxygen starts breaking it down. The American Heart Association says to replace your nitroglycerin every 3 to 6 months after opening, no matter how many tablets are left.

Patients who use expired nitroglycerin during chest pain often report it doesn’t relieve their symptoms. In one Baptist Health study, 78% of patients who used expired tablets needed emergency care. Those using fresh ones? Only 22%. That’s not a small difference. That’s the difference between walking out of the ER and ending up on a ventilator.

Never transfer nitroglycerin to a pill organizer. Don’t store it in your purse, glove compartment, or medicine cabinet. Keep it in its original amber glass bottle, tightly closed, and away from heat and light. If it smells like vinegar, it’s gone bad. Toss it.

Storage Matters More Than You Think

Expiration dates assume you’ve stored the drug correctly. But most people don’t. Insulin left in a hot car for an hour? Useless. EpiPen stored in a bathroom with steam and humidity? Degraded. Nitroglycerin kept in a drawer with other pills? Probably dead.

Insulin: Keep unopened in the fridge. Once opened, store at room temperature. Never freeze it. Never leave it in direct sunlight.

EpiPen: Carry it with you. Don’t store it in your car, even in winter. Heat and cold both damage it. Keep it in your pocket or a waist pouch.

Nitroglycerin: Always keep it in the original bottle. Don’t open it until you need it. Replace it every 3-6 months, even if you haven’t used it.

Smart packaging is starting to appear. Sanofi’s Toujeo Max insulin lasts 56 days at room temperature. Adamis’s Symjepi EpiPen lasts 24 months. Vericel’s smart nitroglycerin, still in trials, changes color when potency drops. But until those become standard, assume your meds are fragile.

What Experts Say

Dr. Robert Hodes of the Cleveland Clinic says: “Having the wrong dose of these types of medications could lead to a medical emergency.” Dr. Jonathan Gipps of Baptist Health warns: “Patients use expired nitroglycerin for chest pains and end up in the ER.” Dr. Sanjay Gupta on CNN put it bluntly: “The shelf life of insulin is non-negotiable.”

These aren’t opinions. They’re based on real cases, real data, and real deaths. The FDA doesn’t set expiration dates to make money. They’re based on stability testing. For insulin, epinephrine, and nitroglycerin, that testing shows rapid, dangerous degradation.

What to Do If You Can’t Afford New Ones

A University of Michigan study found 43% of low-income patients use expired insulin because they can’t afford new ones. That’s heartbreaking. But it’s also deadly. If you’re struggling:

• Ask your doctor for samples or patient assistance programs. Many manufacturers offer free insulin for those who qualify.
• Check if your pharmacy has a discount program. Some insulin brands cost under $25 with coupons.
• Call your local health department. Many offer free or low-cost emergency medication kits.
• Never risk your life by using expired medication. There are options. Use them.

How to Stay on Top of Expiration Dates

The biggest problem? People forget. A University Hospitals study found 67% of cardiac patients had expired nitroglycerin in their emergency kits. Here’s how to fix that:

1. Write the opening date on every insulin vial or pen with a permanent marker.
2. Set phone alerts: 28 days after opening insulin, 3 months after opening nitroglycerin, 12 months before EpiPen expiration.
3. Keep a small notebook or digital list: Medication | Expiration | Opened On | Replace By.
4. When you refill, throw out the old one immediately. Don’t keep “just in case.”
5. Check your emergency kit every season. Don’t wait for a crisis to find out it’s expired.

How to Dispose of Expired Medications

Don’t flush them. Don’t toss them in the trash. Expired insulin and epinephrine are hazardous waste. The FDA recommends returning them to a pharmacy with a drug take-back program. Many pharmacies offer free disposal. If yours doesn’t, call your local health department. They’ll know where to drop them off safely.

Nitroglycerin tablets? Wrap them in paper, seal them in a plastic bag, and take them to a pharmacy. Don’t let them sit in your medicine cabinet for years.

Final Warning

These aren’t ordinary medications. They’re emergency tools. You don’t get a second chance with insulin, EpiPens, or nitroglycerin. If they’re expired, they’re not just old-they’re dangerous. Replace them on time. Store them right. Check them monthly. Your life, or someone else’s, depends on it.

If you’re managing one of these critical medications, don’t wait for a crisis to check your supplies. Set reminders. Replace them on time. Your life depends on it.