Asthma vs allergies: what’s the difference?

Posted on 1 May 2018

Asthma is estimated to affect 20% of South African schoolchildren and up to 10% of adults. With allergies reportedly on the rise, it is important to understand the link between asthma and allergies.

Allergies are the immune system’s hypersensitive (or inappropriate) response to generally harmless substances (allergens) that it comes into contact with either through direct contact, breathing in or eating.

An allergen is any substance that causes an adverse immune or allergic (hypersensitive) reaction. Common allergens include:

Many allergens are harmless and will not cause any reactions in people who are not allergic. In those with allergies, however, their body’s immune system will react to the allergen as if it were foreign and harmful and it tries to protect the body from the substance by releasing histamines. The release of histamine then causes all the classic symptoms of an allergic reaction.

Allergic reactions depend on the allergen and how sensitive the person is to the allergen. Reactions can range from mild to severe, and even life-threatening in some cases. Common symptoms of allergic reactions include:

  • Sneezing
  • Runny or stuffy nose
  • Itchy eyes, nose or roof of the mouth
  • Red, swollen, watery eyes
  • Hives
  • Swelling of the mucous (mucosal) tissues
  • Coughing or wheezing

Anaphylaxis is a more serious allergic reaction that can be life-threatening. Anaphylaxis symptoms usually occur within minutes of exposure to an allergen but can take up to 30- 60 minutes. These reactions involve more than one system in the body and may include the following:

  • Low blood pressure
  • Hoarse voice
  • Swelling of the tongue or throat
  • Wheezing and trouble breathing
  • Inability to swallow
  • Swelling of other parts of the body
  • A weak and rapid pulse
  • Nausea, vomiting or diarrhoea
  • Dizziness or fainting
  • Skin reactions, including hives and itching and flushed or pale skin

Is asthma related to allergies?

Allergies and asthma often occur together, along with eczema, as they are all common presentations of atopy – a syndrome characterised by a heightened immune response to common allergens.

Common symptoms that could indicate asthma include the often-overlooked associated symptoms of allergy: itchy eyes, a chronic runny or blocked nose, and eczema.

Therefore, the same allergens that precipitate an allergy in people may also cause an asthma attack in others.

It’s also important to understand that asthma can be identified as “allergic” and “non-allergic”. Allergic or allergy-induced asthma is more common among children and responds well to conventional treatment.

Adult-onset asthma is often of the non-allergic variety and is linked to other chronic conditions like rhinosinusitis (a common disorder related to inflammation of your nasal passages and sinus cavities) and gastroesophageal reflux disease (GORD). GORD is a digestive disorder that affects the lower oesophageal sphincter, the ring of muscle between the oesophagus and stomach. Non-allergic triggers can also range from infections, exercise and even changes in weather or emotional states.

The first plan of action is always prevention:

  1. Know your triggers (you can find some of these out with an allergy test)
  2. Stick to the asthma action plan your doctor has provided and take the long-term controller medicines (preventers) and relievers
  3. Use quick-relief medicines to stop asthma attacks when they happen
  4. Have someone dust and vacuum to get rid of dust, pollen, and pet dander
  5. Wash your sheets and blankets in hot water, weekly
  6. Have someone clean up any mould in your home; look in the dark and hard-to-reach places too
  7. Have an annual flu shot. Check with your doctor first if you are allergic to eggs. (Most flu shots and the nasal spray flu vaccine are manufactured using egg-based technology, however, they may still be considered safe).

During an asthma attack, the airways tighten, swell up, or fill with mucus and symptoms worsen suddenly. Common symptoms include coughing, wheezing, chest tightness, pain, or pressure and shortness of breath or trouble breathing.

Symptoms differ from case to case, but in the event of a suspected asthma attack, follow the guidelines laid out in a customised asthma action plan from your doctor. In very severe cases, you may need to be hospitalised and admitted to the Critical Care Unit (CCU). If you suspect a severe attack, do not delay treatment and call ER24 on 084 124.

For more information for patients and medical professionals, the National Asthma Education Programme of South Africa offers resources, training and up-to-date information on the condition.


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Published in Healthy Life

In the interest of our patients, in accordance with SA law and our commitment to expertise, Mediclinic cannot subscribe to the practice of online diagnosis. Please consult a medical professional for specific medical advice. If you have any major concerns, please see your doctor for an assessment. If you have any cause for concern, your GP will be able to direct you to the appropriate specialists.

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