Epinephrine for anaphylaxis

On rare occasions, a person can suffer a severe rapid allergic reaction (also called anaphylaxis or anaphylactic shock) after getting exposed to something they are allergic to, such as a particular food, medication, insect sting, chemical or material.

In many instances of anaphylaxis, the cause (the allergen that triggered the reaction) cannot be identified so the reaction is called idiopathic anaphylaxis. If a cause was found, that allergen was probably one of the following:

• Peanuts, tree nuts, shellfish, fish, cow's milk or eggs.
• Antibiotics (especially the penicillin family), NSAID drugs (aspirin and ibuprofen family), or radiology contrast dye.
• Bee, wasp, or hornet stings; fire ant bites.
• Latex (such as latex in gloves, condoms, or medical devices).

If a bystander sees a person having a severe rapid allergic reaction, the bystander can call 911 for paramedics while doing first aid, which is an injection of epinephrine into the thigh. You might be the bystander, but on rare occasions you could be the patient (the person having the reaction); a bystander and patient can work together to get help.

The two main issues are: How can you tell a person is having anaphylaxis, and what should you do in such an event? A patient with anaphylaxis usually has more than one symptom, and symptoms worsen as the minutes go by. The patient may have:

• Rapid onset of symptoms within a few minutes to half an hour after exposure to the cause (occasionally, anaphylaxis happens later, such as several hours after contact with the allergen).
• Hives (itchy skin welts) or generalized skin itching or redness.
• Swelling of the face, lips, tongue, or throat.
• Trouble breathing, such as with wheezing, coughing, or chest tightness.
• Dropping blood pressure, which can cause dizziness, lightheadedness, fast heart rate, or sweating.
• Other less common symptoms such as stomach cramps or vomiting.

After deciding the patient probably has anaphylaxis or is starting to have an anaphylactic reaction, first aid treatment is by giving an injection of epinephrine:

• A bystander can promptly inject epinephrine into the patient's thigh, or the patient can do a self-injection.
• If the epinephrine is an auto-injector device, read the label to make sure the correct end of the injector is pressed against the thigh.
• Inject into the outer side of either the left or right thigh, because those muscle areas don't have big blood vessels or nerves.
• If the epinephrine is stored somewhere else (not carried by the patient), it may be safer for a bystander to run to a first aid station or school nurse, get the epinephrine, and run back to the patient. A patient with dropping blood pressure may go unconscious if a bystander tries to make them stand or walk (lying down with legs partly raised helps blood get to the head and maintain consciousness).
• Call 911 for an ambulance right after injecting, or at the same time if somebody is free to make the call.

Here are additional helpful tips:

• Epinephrine allergy kits and injectors of several brands have the same strength and dosing. The strength is a concentration of 1 mg/mL, and the dosing is:

  • Regular dose for a patient weighing 66 lbs. or more (at least 30 kg): 0.3 mg (equals 0.3 mL of the epinephrine liquid).

  • Young child dose for 33–66 lb. patient (15–30 kg): 0.15 mg (equals 0.15 mL of the epinephrine).

  • Baby dose for 16–33 lb. patient (7.5–15 kg): 0.1 mg (equals 0.1 mL of the drug)

• Allergy kits and injectors available in the US range from under $50 for a vial of epinephrine plus syringes, to over $600 for brand name auto-injectors. They are all equally effective because the drug is the same inside them.

• If you are caring for others, such as at school, camp, or recreational events, be sure to watch online videos to learn how each type of injector works.

• If you are buying epinephrine for yourself, pick an injector that you can afford, remember to carry all the time, and learn to use correctly (some are compact enough to fit in a small pocket, and some are simpler to use than others).

In 2023, available epinephrine choices in the U.S. include:

• Adrenalin vial plus syringe (available also in generic).
• Adrenaclick injector (considered a "generic epinephrine auto-injector" by some insurers).
• Auvi-Q injector.
• EpiPen injector (available also in generic).
• Symjepi injector.

Follow-up care is important after injecting epinephrine for anaphylaxis:

• Another dose may be needed 5–15 minutes later (paramedics may have arrived and can help decide on additional doses).

• A medical provider can assess the patient to decide how long observation at the hospital is needed, such as being watched for 10–24 hours.

• After recovery, the patient should see their primary care provider (PCP) to discuss how to prevent future anaphylaxis events, mainly by avoiding allergen triggers, plus how to properly carry and use an epinephrine injector.

  • For example, a couple of days after fully recovering from a severe allergic reaction, a patient can do a video visit with a HealthTap primary care doctor to review the events and decide on the best course of care going forward.