If you or a family member has allergies to foods, medicines, insect stings or other triggers, knowing how to use an epinephrine auto-injector (EpiPen and others) can be lifesaving. Yet most people who use the devices don't do it entirely correctly.

That's the finding of a recent study from a team of physicians at University of Texas Medical Branch in Galveston, Texas. The doctors found 84 percent of the 102 patients who injected epinephrine for an allergic reaction got at least one step wrong. More than half of the patients — 56 in total — got three or more steps wrong.

The most common error was not holding the unit in place for at least 10 seconds after triggering the device. Other common errors included failure to place the needle end of the device on the thigh and failure to depress the device forcefully enough to activate the injection.

Anaphylaxis, the serious allergic reaction these injectors are meant to treat, can be deadly if not stopped. Learn a few tips before using an epinephrine auto-injector to make sure you do it right.

Related: Anaphylaxis: Beware the Double Whammy

When to use one

Your doctor will educate you on when an injection of epinephrine is needed. She may instruct you to use an auto-injector if you are having an allergic reaction and having trouble breathing, feeling tightness in your throat or feeling as if you might pass out.

If a child is having a serious allergic reaction and is in danger of passing out, is coughing repeatedly, develops widespread hives, or has eaten a trigger food that has caused a life-threatening allergic reaction before, injection is also often advised.

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A five-step process

This process is for auto-injection using an EpiPen, the most commonly used device. If your auto-injector is another type, follow the instructions on the device exactly; they will differ slightly.

1. Open: Flip open the cap of the carrier tube. Remove the pen from the tube.

2. Prepare: Make a fist around the EpiPen with your dominant hand. Be sure the orange-tipped end faces down. With your other hand, pull off the blue safety release.

3. Inject: Hold the orange tip of the EpiPen near your outer thigh, then swing and firmly push it against the outer thigh, at a 90-degree angle to the thigh, until you hear the injector click. Hold the injector in place for 10 seconds to be sure enough epinephrine goes in. It can be injected through clothing.

4. Remove: Take the pen out of the thigh. The orange cover will automatically cover the needle.

5. Massage: Gently massage the injected area for 10 seconds.

Next steps

That's the entire process for the injection, but you're not done. Go to the nearest emergency department; do not drive yourself. Take the injector with you so it can be disposed of properly.

At the ER, you will continue to be monitored. That is in case of a second reaction, which is not common but possible. You may be under observation for several hours, and you may be given other medicines.

Related: The ABCs of Food Allergies in the Classroom

Being prepared

After you use your EpiPen, your health care provider will prescribe another supply to keep on hand.

Check the expiration dates and replenish the pens before they expire. Keep two doses on hand at all times, advises the American Academy of Pediatrics (AAP). Children should have a dose at school, with instructions from their doctors about how to use it.

For children with severe allergies, be sure caregivers, teachers and others who are with your child are aware of the allergies and how to use the epinephrine auto-injector, advises the AAP. Be sure others know where it is stored at home.

The injectors should be stored at room temperature, away from extreme cold and heat. It's a good idea to inspect the cartridge window once in a while to be sure the solution is still colorless and has no floating particles. If you see either problem, the injector should be replaced, according to UPtoDate, a medical information resource for physicians.

Related: Allergy Proof Your Kids — Not Your House

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Kathleen Doheny is a Los Angeles journalist specializing in health, behavior and fitness topics.