Anaphylaxis

Anaphylaxis is the most severe form of allergic reaction and is potentially life threatening. It must be treated as a medical emergency, requiring immediate treatment and urgent medical attention. Anaphylaxis is a severe allergic reaction, which often involves more than one body system. A severe allergic reaction usually occurs within 20 minutes of exposure to the trigger. Severe allergic reactions may occur without prior exposure to a trigger. It is characterised by rapidly developing airway and/or breathing and/or circulation problems usually associated with swelling, redness or itching of the skin, eyes, nose, throat, or mouth.

Many substances can cause anaphylaxis, but more common causes include:

• Foods (especially peanuts, tree nuts, cow’s milk, eggs, wheat, seafood, fish, soy, sesame)
• Drugs (eg: penicillin)
• Venom from bites (ticks) or stings (e.g., bees, wasps or ants).

Recognition of Anaphylaxis

Anaphylaxis encompasses a variety of signs and symptoms. Diagnosis is largely based on history and physical findings. Onset can range from minutes to hours after exposure to a substance.

Signs and symptoms are highly variable and may include one or more of the following:

• Difficult/noisy breathing
• Wheeze or persistent cough
• Swelling of tongue
• Swelling/tightness in throat
• Difficulty talking and/or hoarse voice.
• Persistent dizziness/loss of consciousness and/or collapse
• Pale and floppy (young children)
• Abdominal pain and vomiting (insect allergy only)

Adrenaline (epinephrine)

Adrenaline (epinephrine) is the first line drug treatment for anaphylaxis.

The common form of this drug is the self-injecting EpiPen®.  These contain single-use doses of adrenaline for the treatment of anaphylaxis.

There are two adrenaline doses available via the EpiPen®.

1. The adult EpiPen is for children over 5 years old and for teenagers and adults.
2. The junior EpiPen is for children under 5 years of age.

Adrenaline is rapidly absorbed when injected into the outer muscle of the mid-thigh and can be injected through thin clothing.

Treatment for Anaphylaxis

People with diagnosed allergies should avoid all trigger agents/confirmed allergens.  People who have had a prior episode of anaphylaxis are prescribed adrenaline (epinephrine) in the form of an autoinjector.  They should have a readily accessible ‘Anaphylaxis Action Plan’ and medical alert device. Whenever possible, this information should be sought and implemented, provided this does not delay emergency treatment.

Emergency treatment

The early administration of adrenaline (epinephrine) is the priority in the emergency treatment of anaphylaxis. 

If the victim’s signs and symptoms suggest anaphylaxis the following steps should be followed.

1. Lay the victim flat; do not stand or walk. If breathing is difficult, allow to sit (if able)
2. Prevent further exposure to the triggering/agent if possible.
3. Administer adrenaline (EpiPen®) via intramuscular injection into the thigh.
4. Call an ambulance.
5. A second dose of adrenaline (epinephrine) can be administered by auto injector to victims whose anaphylaxis symptoms are not relieved by the initial dose.  The second dose is given 5 minutes after the initial dose.
6. If victim becomes unresponsive and not breathing normally, commence resuscitation.

If unsure whether it is anaphylaxis, give adrenaline.  The risks of not giving adrenaline far outweigh any potential side effects, such as increased heart rate, increased blood pressure, shaking, nervousness or headache.

Regularly check the expiry date of autoinjectors.  If the adrenaline is expired, replace immediately.

In an emergency, expired adrenaline may only be used if there is no other option available.