Anaphylaxis: Symptoms, Causes & Treatment

Anaphylaxis is the most dangerous type of allergic reaction and is considered a life-threatening emergency. It occurs when the immune system launches a severe, sudden allergic response to an allergen, so several body systems are affected at once and within minutes. Among its most common triggers are some foods (such as tree nuts, peanuts, shellfish, milk, and eggs), insect stings (such as bees and wasps), some medications, and latex.

Anaphylaxis symptoms develop very quickly and involve more than one system: on the skin a spreading rash and hives, itching, redness, and swelling of the face and lips; in breathing difficulty breathing, wheezing, throat tightness, hoarseness, and a feeling of the throat closing; in the circulation a sharp drop in blood pressure, dizziness, pallor, a fast pulse, and possibly loss of consciousness; and in digestion abdominal pain, vomiting, and diarrhea may occur. What distinguishes anaphylaxis and makes it dangerous is its speed and its affecting more than one system together, as it may progress from mild symptoms to a critical state within minutes.

Managing anaphylaxis cannot tolerate delay, and the first life-saving treatment is injecting adrenaline into the outer thigh muscle immediately on suspecting anaphylaxis (no waiting, and no reliance on antihistamines alone which are not enough). If the person has a self-injectable adrenaline pen (for those previously diagnosed with severe allergy) it must be used right away, then emergency services called immediately even if symptoms improve, because the reaction may return (a biphasic reaction). It is preferable to keep the affected person lying down with the legs raised (unless they have difficulty breathing, then they sit). A second adrenaline dose may be needed if the condition does not improve. Prevention relies on strictly avoiding the known allergen, always carrying the self-injectable adrenaline pen for those at risk, training the patient and their family to recognize symptoms and use the pen, and wearing a medical alert bracelet.

• Difficulty breathing, wheezing, tightness, throat swelling, and hoarseness.
• A spreading rash and hives, itching, and swelling of the face and lips.
• Low blood pressure, dizziness, pallor, a fast pulse, and possibly loss of consciousness.
• Abdominal pain, vomiting, and diarrhea sometimes.

• Foods (tree nuts, peanuts, shellfish, milk, eggs).
• Insect stings (bees, wasps).
• Some medications and latex.

• Urgent clinical diagnosis from the rapid multi-system symptoms after exposure to an allergen.
• Treatment does not wait for test results.
• Later evaluation by an allergist to identify the allergen and set a plan.

Immediate life-saving treatment

• Injecting adrenaline into the outer thigh muscle immediately on suspicion (no waiting).
• Calling emergency services directly even if symptoms improve (the reaction may return).
• Keeping the person lying down with legs raised (or sitting if breathing is difficult).
• A second adrenaline dose may be needed if the condition does not improve.

Antihistamines alone are not enough for anaphylaxis. This content is educational and does not replace emergency medical care.

• Airway obstruction and severe difficulty breathing.
• Shock and a severe drop in blood pressure that may threaten life.
• Return of the reaction after temporary improvement (a biphasic reaction).

• Strictly avoiding the known allergen (food, medication, stings).
• Always carrying the self-injectable adrenaline pen for those at risk.
• Training the patient and family on symptoms and using the pen, and wearing a medical alert bracelet.