1. Mild allergic reactions include symptoms that affect the skin and the layers just underneath the skin, such as hives or itchy, watery eyes.
2. Moderate allergic reactions include symptoms that suggest cardiovascular, respiratory or gastrointestinal involvement, such as difficulty breathing or vomiting.
3. Severe allergic reactions may begin with a sudden onset of a mild or moderate reaction and quickly progress into severe symptoms, which are hypotension (low blood pressure), confusion, loss of consciousness, or neurological compromise.

Anaphylactic shock is the most severe type of anaphylaxis. It involves a sudden drop in blood pressure and the bronchial tubes to narrow, thereby causing dizziness, mental confusion, difficulty breathing or even unconsciousness or even death.

Most anaphylactic symptoms and reactions occur within minutes after exposure to the allergen. However, there is a possibility that the reaction is delayed for hours. Another possibility is that a person may experience a dual phase allergic reaction, which is characterized by an initial allergic reaction followed by a recurrence of the symptoms approximately 4-8 hours later.

It is noteworthy to mention that although anaphylaxis is generally defined as a “severe allergic reaction,” the severity of an anaphylactic attack is still categorized as either mild, moderate, and severe categories.