Practical Considerations about Covid-19. Click here to Learn more

What is an Allergy??

Allergy is a very common medical condition. People may have an allergy to almost any food, chemical, drug or other materials. But what is an allergy really? Let's take a closer look in the article below:

Before and After photos of a lady of african background with an allergy reaction from hair dye
Allergy effect from hair dye. Credit Source - Hairsimply

An allergy is your body’s response to a substance - usually a foreign body - that it does not agree with.

Allergies are very common; especially in children though they mostly outgrow them.

Food allergies are among frequently occuring events in children.

'Hypersensitivity' and 'reaction' are words also used to describe the body’s reaction to the substance causing the allergy.

What Are 'Allergens'?

Allergens are the substance that cause or trigger an allergy reaction.

Sometimes we do not know what causes the reaction.

But allergens can include: medicines, foods, fibre used in clothing, animals or animal hair, chemicals, dust, grass and tree pollen, cosmetics like makeup, hair dyes or henna, creams or household chemicals like soaps etc.

How does an Allergy Happen?

Well, there are certain cells in the body that become stimulated when the body encounters an allergic substance, allergen or trigger.

These cells proceed to ‘react’ against the trigger giving rise to the allergy and the symptoms we see.

Most often, allergy reactions are mild; but occasionally they can be very severe or even life threatening.

Symptoms of Allergy

These can include:

  • Skin rash that is itchy, burning and can occur all over the body;
  • Runny nose, itchy and runny eyes, sneezing as happens in hay fever;
  • Swelling of the face, eyes, lips and tongue.

The most serious type of allergy is called an anaphylactic reaction.
It is a medical emergency where; as a result of severe sensitivity to a substance the body has an overwhelming reaction and it’s tissues go into 'shock' as a result.

The Symptoms of Anaphylactic Reaction:

In an anaphylactic reaction things can happen very quickly.

The symptoms usually start soon after exposure to the trigger such as an injection - during baby immunisation for example; or a blood transfusion with incorrect blood type.

Other examples could be following Henna or hair dye application, or if a person eats a food they are allergic to like peanuts.

  • Fast heart rate
  • Sweating
  • Difficulty breathing or breathing very fast
  • Loss in colour (going pale)
  • Sudden onset of a quickly spreading rash
  • Tongue swelling
  • Swelling of the eyes, lips, throat
  • Feeling faint, sick, dizzy, a sense of urgency or disaster about to happen.

Other aspects of Anaphylaxis

Commonly people may have Anaphylactic reactions to:

  • Fish or shellfish
  • Peanuts or other types of nuts
  • Certain medicines  - antibiotics like penicillin, for example.

Such people who are known to suffer from anaphylactic reactions must carry an EpiPen.

An Epipen is an injection of Adrenaline that you always carry on your person.

You (or others around you) can give yourself the injection immediately if you start to have a serious allergy reaction.

Adrenaline immediately works to reverse the effects of the anaphylactic reaction.

Read here about dealing with Child Emergencies in school.

For less severe reactions, medicines called Antihistamines are used to counter the effect of the allergy.

This is because critically, one of the chemicals created by the body after it's exposure to a trigger is to form Histamine and this chemical causes a lot of the symptoms we see.

Some Antihistamines can be purchased over the counter.

If you suspect that you (or your child) have an allergy see your doctor to get diagnosed and advise on how to treat it; medicines to use and what to avoid.

Editing By AskAwayHealth Team


All AskAwayHealth articles are written by practising  Medical Practitioners on a wide range of health care conditions to provide evidence-based guidance and to help promote quality health care. The advice in our material is not meant to replace the management of your specific condition by a qualified health care practitioner.To discuss your condition, please contact a health practitioner or reach us directly through

Tagged In: Allergy

Related Post

Founder's Corner
Dr Sylvia Kama-Kieghe

Founder, AskAwayHealth

More Details

Latest Posts

Improve Your Heart Health with Diet

Tips To Relieve Bloating After Meals

Tips for the Best Sleep 2022

FutureLearn Limited

Birth Control – Risks of IUD Falling Out!

Naturally Better Herbal Gummies | Shop Now

3 thoughts on "What is an Allergy??"

  1. Makwal Levi yakubu says:

    Thanks so much Dr, I might be battling with hay fever based on the symptoms you highlighted and most times if I visit a hospital they prescribed antihistamine drugs sometimes I get a relief while sometimes I don’t. Please what can I do to avoid the triggers .

    1. administrator says:

      Hello Makwal, thanks for dropping a comment!
      If you do have hay fever, you may have symptoms like runny /congested nose, itchy runny eyes and sneezing a lot.

      To be on the safe side, you should see a doctor to ensure this is the right diagnosis.
      People with hay fever may need to be on regular antihistamines. Sometimes after you’ve used an antihistamine for a long time, your body may develop ‘tolerance’- that is, it no longer works as well for you as it did previously. Changing the antihistamine medication may be necessary.

      There are also antihistamine eye drops that could help your symptoms.
      In addition, hay fever may be problem at some periods during the year – this could be at a time when the pollen count is very high; or you may find there are specific things that trigger your symptoms – it could be dust, pets/ animal hair, chemicals etc.

      Key is trying to identify your trigger.
      If it’s pollen or dust related, making sure to keep the windows and doors in your house shut in the early evenings; avoid drying your laundry near grass/ trees, and having a bath to wash off pollen or allergen contacts may be useful too. Let me know if this helps.

      Best wishes, Dr Sylvia

Leave a Reply

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

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Need more

Ask Here

Would you like to consult with a doctor? (UK patients only)

Get e-Consultation Now