Conditions that mimic anaphylaxis include panic attacks, asthma exacerbations, syncope (fainting), and angioedema, but also rarer issues like mast cell disorders, carcinoid syndrome, vocal cord dysfunction, and factitious disorder, all presenting with sudden symptoms like shortness of breath, hives, or swelling, making accurate diagnosis crucial but challenging.

What can be confused with anaphylaxis?

Any condition that may result in the sudden, dramatic collapse of the patient, such as myocardial ischemia, pulmonary embolism, foreign body aspiration, acute poisoning, hypoglycemia, and seizure, can be confused with severe anaphylaxis. However, a vasovagal event is the most common condition confused with anaphylaxis.

What looks like anaphylaxis but isn't?

Diseases that mimic anaphylaxis

Angioedema: In angioedema, there are recurring episodes of painless swelling that may involve the lips, face (especially around the eyes) tongue, upper airway or anywhere in the body.

Can anaphylaxis cause diarrhea?

Gastrointestinal symptoms, such as severe abdominal pain, vomiting and diarrhea, may also occur.

Can anaphylaxis be misdiagnosed?

Anaphylaxis can be misdiagnosed when based on only symptoms, particularly if occurred multiple times. We describe 2 cases that illustrate the complexity of presentation and approaches for evaluation. Both patients claimed strong symptoms, initially and repeatedly, that led to the diagnosis of anaphylaxis.

Anaphylaxis, Animation

What autoimmune disease mimics anaphylaxis?

Idiopathic Mast Cell Activation Syndrome

MCAS is a condition in which the patient experiences repeated episodes of the symptoms of anaphylaxis – allergic symptoms such as hives, swelling, low blood pressure, difficulty breathing and severe diarrhea. High levels of mast cell mediators are released during those episodes.

What is the rule of 2 for anaphylaxis?

The "rule of 2s" for anaphylaxis refers to typical reaction patterns: symptoms usually start within 2 minutes to 2 hours after exposure (injection, ingestion, contact, inhalation), and a severe reaction often involves involvement of 2 or more body systems (skin, respiratory, cardiovascular, GI) or sudden blood pressure drop after known allergen exposure. It's a guideline to recognize this severe allergic reaction quickly, emphasizing immediate adrenaline (epinephrine) treatment and emergency care, especially given potential biphasic (second wave) reactions. 

What is gut anaphylaxis?

Gastrointestinal anaphylaxis is a very severe reaction caused by the ingestion of foods such as cow's milk, hen's egg, peanut, fish and crustaceans.

What is a differential diagnosis of anaphylaxis?

Differential Diagnosis

The differential diagnoses for anaphylaxis include: Angioedema. Anxiety. Arrhythmias.

Can Benadryl stop anaphylaxis?

FACT: NO, epinephrine is the first-line treatment for anaphylaxis. Antihistamines, like Benadryl®, do not reverse the symptoms of anaphylaxis and should not be used instead of epinephrine.

What medical conditions mimic anaphylaxis?

(See "Anaphylaxis in infants" and "Anaphylaxis during pregnancy, delivery, and lactation" and "Anaphylaxis: Emergency treatment".) Common disorders that mimic anaphylaxis include acute generalized urticaria, acute angioedema, acute asthma exacerbations, syncope (faint), and panic attacks or acute anxiety (table 3).

What exactly is Hoigne syndrome?

Background: Hoigne's syndrome is a pseudoanaphylactic or pseudoallergic reaction that occurs after intramuscular administration of penicillin G procaine or benzathine. These are usually embolic toxic reactions possibly due to vascular occlusion by large crystals of the penicillin salts.

Can anxiety mimic anaphylaxis?

So, yes, when you're so fearful and then you think something's going to happen, then your body can feel a certain way, and you can start feeling that throat closure. You can start feeling that heart racing, the difficulty breathing, the shortness of breath, all of those symptoms start becoming very real.

What blood tests confirm anaphylaxis?

You might be given a blood test to measure the amount of a certain enzyme (tryptase) that can be elevated up to three hours after anaphylaxis. You might be tested for allergies with skin tests or blood tests to help determine your trigger.

Can a person have an unknown cause of anaphylaxis?

Idiopathic anaphylaxis is a rare disorder that results in the same symptoms of anaphylaxis that develop after a severe allergic reaction, however, the 'trigger' or reason for the reaction is unknown. Idiopathic is a medical term that describes a disease or condition that has no known cause.

How to differentiate anaphylaxis from other conditions?

Anaphylaxis is distinguished from a mild or moderate allergic reaction by the sudden involvement of two or more organ systems manifesting with a variety of symptoms such as difficulty breathing, swelling of the tongue, swelling or tightness in the throat, wheezing, sudden persistent cough, abdominal pain, vomiting, and ...

What are the 3 A's of anaphylaxis?

The "3 A's of Anaphylaxis" generally refer to Awareness, Avoidance, and Action, guiding how to manage severe allergic reactions: be Aware of triggers and symptoms, actively Avoid allergens, and take prompt Action (using epinephrine) if exposure occurs. This framework emphasizes recognizing the emergency, preventing exposure, and acting quickly with prescribed medication like an EpiPen. 

What is a Type 4 anaphylactic reaction?

Type IV hypersensitivity, or delayed hypersensitivity reactions, are T-cell–mediated immune responses that typically manifest 48 to 72 hours after antigen exposure, although they can take weeks to manifest.

What does mild anaphylaxis feel like?

Stage one: Mild anaphylaxis is the first stage and can cause symptoms like skin rash or redness, itching or hives. Stage two: Moderate anaphylaxis happens when a person has more widespread and extensive symptoms like skin rash and hives that are spreading or mild swelling in their lips or tongue.

What is a systemic symptom of anaphylaxis?

Low blood pressure (hypotension) Constriction of the airways and a swollen tongue or throat, which can cause wheezing and trouble breathing. A weak and rapid pulse. Nausea, vomiting or diarrhea.

What is biphasic anaphylaxis?

“Biphasic anaphylaxis” (BA) was defined as an anaphylactic reaction consisting of 2 distinct phases separated by at least 1 hour, with both phases meeting internationally recognized diagnostic criteria for anaphylaxis.

What is the longest anaphylaxis can take?

Most anaphylactic reactions begin within minutes of exposure to an allergen. However, in some cases the reaction can take a half hour or longer.

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