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Signs and Symptoms of Allergic Reactions

Despite being careful, you may accidentally come in contact with something to which you are allergic or even a derivative/cross reactive product that your immune system identifies as the original allergen. 

Immediate Hypersensitivity Allergic Reactions

This is caused by sensitized body cells over-producing specific IgE.

Here are some common hypersensitivity symptoms listed by the body system affected: 


  • Nettle Rash (Hives or Urticaria)
  • Swelling in the face, throat, and/or mouth (or other areas depending on where the allergen in absorbed)
  • Itching
  • Rash
  • Warm and flushed skin


Eyes Ears Throat Mouth

  • Tingling or itchy feeling in the mouth 
  • Nasal congestion or sneezing
  • Itchy or runny nose
  • Watery or itchy eyes
  • Swelling
  • Throat pain or clearing
  • Throat swelling
  • Asphyxiation



  • Chest tightness
  • Difficulty breathing
  • Wheezing
  • Cough
  • Asthma attack



  • Weak and floppy
  • Heart racing
  • Low blood pressure causing dizziness / fainting
  • Weak pulse
  • Pale or blue skin when severe



  • Nausea and vomiting
  • Feeling of acid reflux or upset stomach
  • Cramping and diarrhea



  • Inconsolable
  • Anxiety or panic
  • Feeling of impending doom

In extreme cases, life-threatening anaphylaxis could happen and a sudden drop in blood pressure would cause anaphylactic shock.

Have an Anaphylaxis Action Plan (A.A.P.)

An AAP may assist you and your loved ones in identifying allergic reactions, as well as give you a guide to how to react quickly to treat a reaction and get help.  See our section on Anaphylaxis Action Plans. (insert hyperlink)  The AAP will also help you in decision-making with the use of your epinephrine “rescue” medication, which all people who have a moderate to severe allergy to an ingestible substance should carry.  See our section on Epinephrine for the Treatment of Anaphylaxis. (insert hyperlink)

Delayed Hypersensitivity Allergic Reactions (DTH Reactions)

This is caused by sensitized body cells, such as T-cells white cells that then recruit other cells such as Macrophage and Monocyte type white blood cells to attack the allergen.  The process of identification and recruitment of pro-inflammatory cells and chemicals takes time, therefore an allergic reaction may not be seen immediately.  This type of allergic reaction does not involve antibodies or IgE.   We call this type of reaction,  delayed- hypersensitivity (DTH) or cell-mediated allergic reactions. The result of this type of reaction is cellular destruction.


It may take 2 to 3 days to develop symptoms as follows: 

Allergic contact dermatitis

  • Red, itchy rashes 
  • Dry, cracked, or scaly skin 
  • Bumps and blisters with crusting
  • Swelling, burning, or tenderness in the area
  • Even skin sloughing of dead skin cells


Examples of other types of DTH reactions

Tuberculosis skin reaction (such as a positive TB skin test)

Transplant rejection

Autoimmune tissue inflammation, such as Type 1 Diabetes, Hashimoto’s thyroiditis, inflammatory bowel disease, rheumatoid arthritis joint destruction


MASA clinicians are both allergy and immunology trained and can help you diagnose and evaluate many diseases and develop a treatment plan. Contact us to make an appointment now!

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