Anaphylaxis Response: Recognition, EpiPen Use, and Alternatives

Recognizing Anaphylaxis

Anaphylaxis is a systemic allergic reaction involving multiple organ systems simultaneously. The cardinal rule: anaphylaxis involves more than one body system after allergen exposure.

A single hive after a bee sting is not anaphylaxis. A hive plus wheezing is anaphylaxis. A drop in blood pressure plus vomiting after eating is anaphylaxis.

Common Triggers

• Insect stings: Bees, wasps, hornets. The most common cause of fatal anaphylaxis.
• Foods: Peanuts, tree nuts, shellfish, fish, milk, eggs, wheat, soy
• Medications: Penicillin and related antibiotics, NSAIDs, aspirin
• Latex: Particularly in healthcare settings
• Exercise-induced anaphylaxis: Occurs during exercise, often combined with a recent food trigger

Symptoms by System

Skin (most common: 80-90% of cases):

• Urticaria (hives): raised, red, intensely itchy welts
• Flushing: diffuse redness
• Angioedema: swelling, particularly of lips, tongue, face, throat

Respiratory (life-threatening):

• Stridor: high-pitched inspiratory sound from upper airway swelling
• Wheezing: lower airway bronchospasm
• Sensation of throat tightening or closing
• Difficulty breathing, shortness of breath
• Hoarseness (indicates vocal cord edema)

Cardiovascular:

• Rapid, weak pulse (tachycardia + hypotension)
• Dizziness, lightheadedness
• Syncope (loss of consciousness)
• Pale, clammy skin

Gastrointestinal:

• Nausea, vomiting
• Abdominal cramping
• Diarrhea

Central Nervous System:

• Anxiety, sense of impending doom (this symptom is classically described and diagnostically useful)
• Confusion, altered mental status

Epinephrine: The Only First-Line Treatment

Epinephrine (adrenaline) is the only medication that addresses all components of anaphylaxis: it reverses bronchospasm, supports blood pressure, and reduces upper airway swelling. No other drug is a substitute.

The decision to give epinephrine should be fast. The risk of epinephrine in anaphylaxis is minimal. The risk of delayed epinephrine is death. When anaphylaxis is suspected, give epinephrine first, ask questions later.

EpiPen Technique

Adult dose (EpiPen): 0.3mg epinephrine auto-injector Child dose (EpiPen Jr): 0.15mg (for weight less than 25kg / 55 lbs)

1. Remove the EpiPen from the carrier case.
2. Grip firmly with your dominant hand. Remove the blue safety cap with the other hand — pull straight off, not twisted.
3. Press the orange tip firmly against the outer thigh. The injection is given into the vastus lateralis muscle (outer mid-thigh). It can be given through clothing — do not delay to remove pants.
4. Hold firmly in place and listen for the click, then count 3 seconds.
5. Remove and massage the injection site for 10 seconds.
6. Note the time of injection. Relay this to paramedics.
7. Do not put your thumb over the orange tip — this is where the needle exits.

If the patient is unable to administer it themselves and you are giving it, confirm you are on the outer thigh and not over the kneecap or hip bone.

What to Expect After Injection

Epinephrine works within 1-5 minutes. Expect:

• Rapid heart rate (this is the drug working)
• Trembling hands, anxiety sensation (normal epinephrine effect)
• Improvement in breathing and skin symptoms within 5-10 minutes

If no improvement after 5-10 minutes, give a second dose if available.

Epinephrine Shelf Life

EpiPens expire. Check dates every 6 months. An expired EpiPen may retain 50-80% of its potency for up to a year past expiration — it is better than nothing, but potency is unreliable. Replace expired devices.

Store at room temperature, away from freezing and extreme heat. Do not store in a car glove box where temperatures exceed 104°F / 40°C.

Positioning

If respiratory symptoms predominate: Sit the patient upright or semi-reclined (like a recliner position). Lying flat with breathing difficulty is poorly tolerated and increases anxiety.

If cardiovascular symptoms predominate (dizziness, syncope, low BP): Lay flat on the back with legs elevated 12-15 inches. This increases venous return to the heart. Do not sit these patients up — you will worsen hypotension.

If both: Use clinical judgment. Compromised airway takes precedence.

If unconscious and breathing: Recovery position (on the side).

When Epinephrine Is Not Available

Without epinephrine, options are limited and less effective. These are adjuncts and last resorts:

Diphenhydramine (Benadryl) 25-50mg oral or IM: Addresses the histamine-mediated component (hives, some itching). Takes 1-2 hours to reach peak effect. Does not reverse bronchospasm or hypotension. Still give it, but do not expect it to stop anaphylaxis.

Cetirizine (Zyrtec) or loratadine (Claritin): Similar antihistamine role, less sedating. Not faster.

Albuterol inhaler (if available): Addresses bronchospasm if the patient has wheezing. Does not address circulatory collapse or upper airway swelling.

Lay flat, legs up: For cardiovascular component. This is a temporizing measure.

Oral steroids (prednisone 40-60mg): Takes hours to work but reduces the biphasic reaction risk. Give as soon as the patient can swallow.

High-dose diphenhydramine 50mg IM has some historical use in severe reactions when epinephrine is unavailable. It is not effective for laryngeal edema or cardiovascular collapse.

The uncomfortable reality: without epinephrine, anaphylaxis with laryngeal edema or cardiovascular collapse has a significant mortality risk. The priority is getting epinephrine and emergency services as fast as possible.

Monitoring for Biphasic Reaction

A biphasic reaction is a second wave of anaphylaxis symptoms occurring 1-12 hours after the initial reaction, even after apparent recovery. It occurs in 5-20% of anaphylaxis cases.

After epinephrine is given and symptoms resolve, the patient must be observed for at least 4-6 hours (emergency department standard is 4-6 hours minimum). Patients who had severe initial reactions are observed for 12-24 hours.

During observation:

• Monitor vital signs every 15 minutes
• Watch for return of any skin, respiratory, or cardiovascular symptoms
• Have epinephrine ready for a second dose

Patients cannot be sent home alone, must not drive, and must have someone with them overnight.

Preparing Before an Emergency

If you or a family member has a known severe allergy:

1. Carry two EpiPens at all times. Two — not one. Second reactions require second doses. The rule is carry two, use one.

2. Have a written action plan. Document allergens, signs of reaction, exact medication doses, and emergency contacts.

3. Train household members and close contacts on EpiPen use. Practice with the training device until it is muscle memory. In a reaction, the person with the allergy may not be able to administer it themselves.

4. Medical alert identification: Bracelet, necklace, or card. In an unconscious patient, this is the information medical responders need.