ALLERGIC REACTION & ANAPHYLAXIS

Anaphylaxis kills in minutes. It is one of the fastest-moving medical emergencies in existence — a patient who was fine at breakfast can be dead before lunch from a bee sting or a bite of the wrong food. It is also, with the right intervention, one of the most reversible emergencies in medicine. Epinephrine administered promptly stops anaphylaxis. Without it, the treatment options are limited and the outcome is significantly worse.

This post covers the spectrum from mild allergic reaction to anaphylactic shock, how to tell the difference, what to do in the field with and without epinephrine, and how to stock and use an auto-injector before you need it.

THE ALLERGIC REACTION SPECTRUM

Mild Allergic Reaction (Localized) Confined to the area of exposure or to the skin. Hives (urticaria) — raised, itchy welts anywhere on the body. Localized redness and swelling at a sting or contact site. Itching. No systemic involvement — no throat tightening, no difficulty breathing, no dizziness, no gastrointestinal symptoms. Can be monitored and treated with antihistamines.

Moderate Allergic Reaction (Systemic, non-anaphylactic) Reaction has spread beyond the immediate area. Widespread hives. Swelling that is not localized to the contact site. Nausea or stomach cramping. No airway involvement, no significant cardiovascular symptoms, no loss of consciousness. Treat with antihistamines. Monitor closely — a moderate reaction can progress to anaphylaxis in some patients.

Anaphylaxis Severe, systemic, life-threatening. Two or more organ systems are involved. Signs develop within minutes to 2 hours of exposure, typically rapidly. Airway involvement, cardiovascular compromise, or both. This is the emergency.

RECOGNIZING ANAPHYLAXIS

Anaphylaxis is present when, after exposure to a likely allergen, the patient develops signs in two or more of the following categories — or cardiovascular collapse alone.

Skin and mucous membranes: Widespread hives, flushing, itching, swelling of the lips, tongue, or face, red watery eyes.

Respiratory: Difficulty breathing, wheezing, stridor (a high-pitched sound on inhalation indicating upper airway narrowing), hoarse voice, sensation of throat closing, chest tightness, cough.

Cardiovascular: Rapid or weak pulse, drop in blood pressure, dizziness, syncope (fainting), pallor.

Gastrointestinal: Nausea, vomiting, abdominal cramping, diarrhea.

Neurological: Confusion, sense of doom, loss of consciousness.

The sensation of throat closing or difficulty breathing after allergen exposure is anaphylaxis until proven otherwise. Do not wait to see if it resolves. Treat.

COMMON TRIGGERS

Insect stings — Hymenoptera (bees, wasps, hornets, fire ants) are the most common cause of fatal anaphylaxis in the field
Foods — Peanuts, tree nuts, shellfish, fish, milk, eggs, wheat, soy are the major eight. In a food storage scenario, label contents clearly.
Medications — Penicillin and related antibiotics, NSAIDs, aspirin
Latex — Relevant to any setting where gloves or medical supplies are used
Exercise-induced — Rare but real; some patients develop anaphylaxis during exercise, particularly in combination with food allergens

A patient who has had a prior anaphylactic reaction is at higher risk for subsequent reactions but not necessarily to the same severity — reactions can be worse, better, or similar to prior episodes. There is no reliable predictor.

TREATMENT — WITH EPINEPHRINE

Epinephrine is the treatment for anaphylaxis. Everything else is secondary. Antihistamines do not treat anaphylaxis — they treat hives. Epinephrine treats the airway compromise and cardiovascular collapse that kill.

Step 1 — Administer epinephrine immediately. Do not wait to see if it gets better. Do not try antihistamines first in a patient with airway symptoms or cardiovascular involvement. Administer epinephrine.

Auto-injector (EpiPen, Auvi-Q, generic epinephrine auto-injectors):

Remove the device from the carrier
Grip firmly with dominant hand, blue/safety end up, orange tip down
Remove the blue safety cap
Press the orange tip firmly against the outer thigh — through clothing is acceptable
Hold for 10 full seconds
Remove and note the time
The orange tip will have extended — confirm by looking for the extended tip

Dose: Standard adult auto-injectors contain 0.3mg epinephrine. Pediatric auto-injectors (EpiPen Jr) contain 0.15mg and are used for children 33lbs-66lbs (15-30kg). Above 66 lbs (30kg), adult dose is used. Below 33lbs (15kg), seek specific guidance.

Injection site: Outer thigh, into the large muscle mass. Can be administered through clothing. Do not inject into the buttocks, hand, feet, or intravenously.

Step 2 — Position. Lay the patient flat with legs elevated (shock position) if they are experiencing cardiovascular symptoms. If they are having difficulty breathing and feel better sitting up, allow sitting. If unconscious, recovery position to protect the airway.

Step 3 — Repeat if no improvement in 5-10 minutes. A second dose of epinephrine can be administered if symptoms are not improving or are worsening after 5-10 minutes. Most kits contain two auto-injectors for this reason. Stock two per person with known allergies.

Step 4 — Antihistamines after epinephrine. Once epinephrine is administered, diphenhydramine (Benadryl) 25-50mg oral or IM addresses the histamine-mediated component of the reaction. This is adjunct treatment, not primary. It does not replace epinephrine.

Step 5 — Monitor for biphasic reaction. Anaphylaxis can recur 4-12 hours after apparent resolution (biphasic anaphylaxis) without re-exposure to the allergen. Any patient who has had anaphylaxis requires monitoring for a minimum of 4-6 hours after recovery.

TREATMENT — WITHOUT EPINEPHRINE

If epinephrine is unavailable, options are limited and outcomes are significantly worse for severe anaphylaxis. Do what is available:

Diphenhydramine (Benadryl) — 50mg oral or IM. Does not treat airway compromise or cardiovascular collapse but may slow the progression of mild to moderate reactions. Sedating. In a patient who is deteriorating, this buys limited time at best.

Positioning — As above. Supine with legs elevated for cardiovascular compromise. Upright for respiratory distress.

Airway management — If the upper airway is closing (stridor, severe hoarse voice, inability to speak), nothing short of surgical airway (cricothyrotomy) can address this without epinephrine. This is beyond basic field medicine for most people. If you have training in surgical airway, this is the scenario where it becomes relevant.

High-dose oral diphenhydramine — Some sources suggest doses above the standard 50mg in desperate circumstances without IV access. This is a last-resort measure with significant sedation and anticholinergic side effects. 100mg oral diphenhydramine is documented in some wilderness medicine protocols as a temporizing measure for anaphylaxis when epinephrine is unavailable.

The honest answer: without epinephrine, severe anaphylaxis is very difficult to treat in the field. This is why having epinephrine available is non-negotiable for anyone with known anaphylactic allergies, and worth having in a general preparedness kit given how common fatal anaphylaxis to insect stings is.

OBTAINING EPINEPHRINE

In the United States, epinephrine auto-injectors require a prescription. For anyone with known allergies, this is standard care — discuss with your physician.

For general preparedness:

Discuss a prescription with your physician in the context of household preparedness. Many physicians will prescribe for this purpose.
Auvi-Q has a patient assistance program that provides free auto-injectors to qualifying individuals.
Generic epinephrine auto-injectors (Amneal, Impax) are less expensive than brand-name EpiPen — ask your pharmacy specifically for the generic.
Shelf life — Auto-injectors expire and epinephrine degrades over time. Check expiration dates annually. Expired auto-injectors retain partial activity and are better than nothing if no alternative is available, but replace on schedule.

Store auto-injectors at room temperature (59-77°F). Do not refrigerate or freeze. Do not store in a hot car — heat accelerates degradation. Check the solution through the window periodically — it should be clear and colorless. Any discoloration means the device should be replaced.

WHAT TO STOCK

Per household with known allergies:

2 epinephrine auto-injectors (EpiPen, Auvi-Q, or generic) — current expiration
Diphenhydramine (Benadryl) 25mg tablets — 50-count minimum
ORS packets for fluid support after stabilization
A written action plan for anyone with known anaphylactic allergies, accessible to everyone in the household

General preparedness kit addition:

2 epinephrine auto-injectors even without known allergies — insect sting anaphylaxis can occur in people with no prior reaction history
Diphenhydramine 25mg tablets in quantity

TRAINING

Knowing the steps above is not the same as having practiced them under stress. If anyone in your household has a known anaphylactic allergy:

Everyone in the household should know where the auto-injectors are stored
Everyone should have practiced the administration steps on a training device (EpiPen makes trainer devices that contain no needle or medication)
The action plan should be written and posted where it can be found without thinking

Cross-reference: Shock — Recognition & Response | Wound Packing | Medications — When SHTF | Insect Identification (Fauna Archive) at kanafia.com.

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