allergic reaction

Close look on an allergic reaction

Fact Checked

An allergic reaction is the response of the immune system in defending the body against viruses and bacteria. In some cases, the immune system defends the body against substances that do not typically poses as a threat to the body.

What causes an allergic reaction?

Generally, allergies usually run in families and can be inherited. Furthermore, if a close family member has allergies, an individual is at higher risk for developing allergies as well.

Even though the exact reason why allergies develop are not known, there are some substances that typically trigger an allergic reaction. Individuals who have allergies are usually allergic to one or more of the following:

  • Animal dander
  • Certain plants
  • Pollen or mold
  • Bee stings or bites from other insects
    Close look on an allergic reaction
    The symptoms of an allergic reaction can range from mild to severe. If exposed to an allergen for the first time, the symptoms are usually mild.
  • Certain medications such as aspirin or penicillin
  • Certain foods including shellfish or nuts

Indications of an allergic reaction

The symptoms of an allergic reaction can range from mild to severe. Generally, iIf exposed to an allergen for the first time, the symptoms are usually mild. Consequently, these symptoms might worsen if repeated exposure occurs.

The indications of a mild allergic reaction include:

  • At first, itchiness arises
  • Hives
  • Rashes
  • Scratchy throat
  • Lastly, itchy or watery eyes

As for severe allergic reactions, it can trigger the following symptoms:

  • Diarrhea
  • Abdominal pain or cramping
  • Chest pain or tightness
  • Difficulty swallowing
  • Facial flushing
  • Dizziness
  • Anxiety or fear
  • Dizziness or vertigo
  • Nausea or vomiting
  • In addition, heart palpitations
  • Weakness
  • Wheezing
  • Swollen eyes, face or tongue
  • Difficulty breathing
  • Lastly, loss of consciousness

Overall, an abrupt and severe allergic reaction can arise within seconds after being exposed to an allergen. This form of reaction is called as anaphylaxis and can trigger dangerous symptoms such as difficulty breathing, swollen airway and abrupt drop in the blood pressure. Consequently, this type of reaction requires immediate medical assistance.


If an individual experiences an allergic reaction and the exact cause is not determined, a doctor should be seen to determine the cause. If an individual has a known allergy and has symptoms, medical care is not required if the symptoms are mild.

In most cases, over-the-counter antihistamines such as diphenhydramine are effective in controlling mild allergic reactions. In addition, if an individual experiences a severe allergic reaction, seek immediate medical care.

Check the individual if he/she is breathing and call for emergency assistance and perform CPR if needed. Generally, individuals with known allergies often have an epinephrine auto-injector. This is a “rescue drug” since it opens the airways and increases the blood pressure. The individual might require assistance in administering the medication.

Generally, if the individual loses consciousness, you should lay him/her flat on his/her back. Elevate the legs and cover with a blanket.

Quick Note / Disclaimer

The material posted on this page on an allergic reaction is for learning and educational purposes only. To learn to recognize and manage allergic reactions, register for a first aid and CPR course with one of our training providers.


Was this post helpful?

Leave a Comment

Your email address will not be published. Required fields are marked *

Shopping Cart
Scroll to Top

  • All content is reviewed by a medical professional and / sourced to ensure as much factual accuracy as possible.

  • We have strict sourcing guidelines and only link to reputable websites, academic research institutions and medical articles.

  • If you feel that any of our content is inaccurate, out-of-date, or otherwise questionable, please contact us through our contact us page.

The information posted on this page is for educational purposes only.
If you need medical advice or help with a diagnosis contact a medical professional