Anaphylaxis: Recognize, React, Recover

What does anaphylaxis mean?

Anaphylaxis is a severe, potentially life-threatening allergic reaction that occurs rapidly—often within minutes—after exposure to a trigger like certain foods, medications, insect stings, or latex.

Cause of anaphylaxis

Key Features of Anaphylaxis

• The immune system's overreaction releases a flood of chemicals, including histamine, which can lead to shock.
• A sudden drop in blood pressure and narrowing of the airways can lead to breathing difficulties.
• Symptoms include hives, itching, flushing, or pale skin.
• Gastrointestinal symptoms: nausea, vomiting, or diarrhea.
• Cardiovascular signs: Weak, rapid pulse; dizziness or fainting.

Common Triggers

• Foods: Peanuts, tree nuts, shellfish, milk, and eggs.
• Medications: Antibiotics, NSAIDs.
• Insect stings: bees and wasps.
• Other substances include latex, exercise, and contrast dyes that are used in imaging.

Emergency Response

• Immediate injection of epinephrine (adrenaline) is critical.
• Call emergency services even if symptoms improve after the injection.
• Hospital observation is needed to monitor for biphasic reactions (a second wave of symptoms).

How long does anaphylaxis last?

Duration of Anaphylaxis

Anaphylaxis typically unfolds in three phases, and its duration can vary depending on the severity, treatment timing, and individual response:

Timeline Overview

• Onset: Symptoms usually begin within seconds to minutes of exposure to the allergen.
• Peak: Most reactions peak within 30 minutes.
• Resolution: With prompt treatment (especially epinephrine), symptoms may improve within a few hours, but full recovery can take up to a day.

Biphasic Reactions

• In 10–20% of cases, symptoms return after initial improvement—this is called a biphasic reaction.
• The second wave of symptoms can occur anywhere from 1 to 72 hours later, but most commonly occurs within 8 to 10 hours.
• This is why hospital observation for at least 4–6 hours is recommended after treatment.

Why Monitoring Matters

Even if symptoms seem resolved, delayed complications like airway swelling or cardiovascular instability can occur. Continuous monitoring ensures timely intervention if symptoms recur. 

How is anaphylaxis treated?

Anaphylaxis Treatment: What to Do Immediately

Anaphylaxis is a medical emergency. The goal is to reverse the allergic reaction quickly and support vital functions like breathing and circulation.

First-Line Treatment

• Epinephrine (Adrenaline): Injected into the outer thigh muscle using an auto-injector (e.g., EpiPen). This is the most critical and life-saving step.
• Timing matters: the sooner epinephrine is given, the better the outcome.

Emergency Medical Care

After epinephrine:

• Please contact emergency services without delay.
• Hospital observation is recommended for at least 4–6 hours to monitor for biphasic reactions, which are a second wave of symptoms.
• Oxygen therapy if breathing is impaired.
• Administer IV antihistamines and corticosteroids to reduce inflammation and prevent recurrence.
• Use beta-agonists, such as albuterol, to treat bronchospasm or wheezing.
• CPR if breathing or heartbeat stops.

Long-Term Management

• Carry an epinephrine auto-injector at all times if you're at risk.
• Avoid known triggers (foods, medications, insect stings, etc.).
• Conduct allergy testing to pinpoint specific allergens.
• Immunotherapy (allergy shots) may help in some cases, especially for insect venom.

What are the potential complications of anaphylaxis?

Complications of Anaphylaxis: What Can Go Wrong

While most people recover fully with prompt treatment, anaphylaxis can lead to serious complications—especially if epinephrine is delayed or the reaction is severe.

Neurological

• Long-term oxygen deprivation causes damage to the brain.
• Low blood pressure or shock can cause confusion, drowsiness, or unconsciousness.

Cardiovascular

• Anaphylactic shock: Sudden drop in blood pressure and poor circulation.
• Arrhythmias or myocardial ischemia can occur, particularly in individuals with heart disease.
• In extreme cases, the patient may experience cardiac arrest.

Respiratory

• Airway obstruction can occur due to swelling of the throat or tongue.
• Bronchospasm can cause wheezing and breathing difficulties.
• If treatment is delayed, it can lead to respiratory failure.

Gastrointestinal

• Vomiting, diarrhea, and abdominal pain can worsen dehydration.

Treatment-related

• Medication side effects, such as those from pressors or steroids, can exacerbate dehydration.
• Complications may arise from CPR or intubation if resuscitation is necessary.

Biphasic Reaction

• A second wave of symptoms can occur 1 to 72 hours later, even after initial recovery.
• This is why hospital observation for 4–6 hours is standard.

Also, read https://dermnetnz.org/topics/anaphylaxis

What are some effective prevention strategies for anaphylaxis?

Anaphylaxis Prevention: Smart Strategies to Stay Safe

Preventing anaphylaxis means avoiding known triggers, being prepared for emergencies, and educating those around you. Here's a structured guide to help you or your patients minimize risk:

Avoid Allergen Exposure

• Identify your triggers through allergy testing and detailed history.
• Read food labels carefully—even trace amounts can cause reactions.
• Ask about ingredients when dining out or at social gatherings.
• Avoid cross-contamination in kitchens and food prep areas.
• For insect allergies, wear protective clothing and avoid perfumes or bright colors outdoors.

Emergency Preparedness

• Carry an epinephrine auto-injector or nasal spray (e.g., Neffy) at all times.
• Wear a medical alert bracelet to inform others of your condition.
• Create an emergency action plan and share it with family, schools, or workplaces.
• Keep an emergency kit with antihistamines, epinephrine, and instructions.

Education & Communication

• Inform healthcare providers of all allergies—especially medication-related.
• Train caregivers, teachers, and coworkers on how to recognize and respond to anaphylaxis.
• Practice using auto-injectors with trainer devices.

Long-Term Strategies

• Consider immunotherapy (e.g., allergy shots) for insect venom or environmental allergens.
• Track symptoms in a journal to identify patterns or hidden triggers.
• Avoid exercise or alcohol near known food triggers if you have exercise-induced anaphylaxis.

What are common triggers for anaphylaxis?

Common Triggers of Anaphylaxis: What to Watch Out For

Anaphylaxis can be triggered by a wide range of allergens—some well-known, others surprisingly obscure. Here's a structured overview to help you educate patients, caregivers, or clinicians:

Food Allergens

• Peanuts and tree nuts (e.g., walnuts, cashews)
• Shellfish and fish
• Milk, eggs, wheat, soy, sesame
• Even trace amounts or cross-contamination can provoke reactions

Medications

• Antibiotics (e.g., penicillin)
• NSAIDs (e.g., ibuprofen, aspirin)
• Anesthesia agents, contrast dyes, and vaccines
• Blood products in hospital settings are a leading cause of fatal reactions

Insect Venom

• Bee, wasp, hornet, and ant stings
• Risk increases with repeated exposure or venom allergies

Latex

• Found in gloves, balloons, and medical devices
• Common in healthcare settings

Exercise-Induced Anaphylaxis

• Triggered by physical activity, especially when combined with food, pollen, or medications

Idiopathic or Hormonal Triggers

• Sometimes, no clear cause is found—called idiopathic anaphylaxis
• Hormonal changes (e.g., menstruation) may play a role

What happens after an anaphylactic reaction?

After an Anaphylactic Reaction: What Comes Next

Recovery doesn’t end when symptoms subside—ongoing care and vigilance are essential to prevent recurrence and manage risks. Here's a structured overview of what typically follows:

Immediate Post-Reaction Care

• Hospital observation for 4–6 hours (or longer) to monitor for biphasic reactions—a second wave of symptoms that can occur within 72 hours.
• Vital signs monitoring, oxygen support, and IV medications (antihistamines and corticosteroids) may be continued.
• Documentation of the event: Details about the trigger, timing, and response are recorded for future care planning.

Medical Follow-Up

• Allergy testing to identify the specific trigger (if unknown).
• Referral to an allergist or immunologist for long-term management.
• Review of medications and potential cross-reactive substances.

Emergency Preparedness

• Prescription for epinephrine auto-injectors (e.g., EpiPen, Auvi-Q, Neffy) with instructions on use.
• Medical alert bracelet to inform others of your allergy.
• Personalized action plan for schools, workplaces, or caregivers.

Education & Lifestyle Adjustments

• Avoidance strategies: Reading labels, asking about ingredients, and preventing cross-contamination.
• Training for family and caregivers on recognizing symptoms and using auto-injectors.
• Behavioral changes: Avoiding exercise or alcohol near known triggers if relevant.

Conclusion

Anaphylaxis is a rapid-onset, potentially fatal allergic reaction that demands swift recognition and immediate treatment. With proper education, preparedness, and trigger avoidance, it’s possible to reduce risks and respond confidently when emergencies arise.