Health x Wellness
Not just a bad rash: What you need to know about Allergy Testing
Allergies are a common condition that involves an “overreaction” of the immune system. These occur when the immune system inappropriately identifies one or more substances that we get exposed to as a threat, and reacts accordingly.
Allergies are a common condition that involves an “overreaction” of the immune system. Our immune system usually makes antibodies to fight off viruses, bacteria, and other things that can make us sick.
Allergies occur when the immune system inappropriately identifies one or more substances that we get exposed to as a threat, and reacts accordingly. They can be idiopathic (no known cause), or hereditary. They also tend to be more common in people with positive family and personal history of allergic rhinitis, eczema, and/or asthma.
Here are some common questions about an allergy.
Are all allergic reactions serious?
We often associate allergies with obvious symptoms such as breathing difficulty or itchiness. However, there are allergic reactions that can be as subtle as the occasional stomach upset, sneezing, or even transient redness of the skin upon exposure to allergens. These reactions can sometimes be temporary and self-limiting and can be easily missed.
When should someone go through an Allergy Test?
An allergy test can be ordered to help with identifying possible allergens in both Food and Non-Food categories, or to confirm a potential allergy reaction based on daily observation by the individuals. Testing should be considered if individuals suspect they are suffering from symptoms of allergies (see below).
Allergy Reaction can manifest in different ways
- Conditions related to respiration, such as Hay fever (allergic rhinitis), and/or Allergic asthma. Symptoms include runny nose, stuffy nose, sneezing, breathing difficulty, cough and wheezing, etc.
- Skin conditions such as Urticaria (Hives) or Dermatitis (eczema). Symptoms include itchy skin, redness, skin patches etc.
- Food allergies or gastrointestinal conditions. Symptoms include nausea, vomiting, diarrhea, bloatedness etc.
- Conditions related to the eye, such as allergic conjunctivitis. Symptoms include watery, itchy and red eyes, etc.
- Anaphylaxis conditions, which can be life threatening. Symptoms include severe breathlessness, swollen tongue and throat, tightening of airway, severe dizziness and collapse. If someone is at risk for anaphylactic shock, they will need to be very careful to avoid the things that they are allergic to.
Types of Allergy Tests offered in DTAP clinics
Skin Prick Test
Checks immediate allergic reactions to different substances, available in Food and Non-Food Categories
Skin prick tests are not painful. There is no bleeding and most patients report only mild discomfort at the test area which subsides quickly.
In adults, the test is usually done on the forearm. The test takes about 20 minutes to produce results.
If you are allergic to one or more of the substances tested, your skin may itch where the allergen is placed. You will develop a raised, red, itchy bump (wheal) that may look like a mosquito bite. Bigger wheals usually indicate a greater degree of sensitivity. A negative skin test means that you are probably not allergic to the allergen tested.
Results may not be accurate if you are taking medications such as antihistamines. This medication should be stopped at least 1 week prior to the test.
Severe eczema on the forearm can sometimes interfere with test result interpretation as well. For patients who are suspected of anaphylaxis reaction upon exposure to the allergen, Skin Prick Tests may be unsafe and are not recommended.
The allergens listed below are available for testing in DTAP clinics
FOOD ALLERGENS:
- Egg
- Cow’s Milk
- Peanut
- Almond
- Wheat
- Soy
- Prawn
- Codfish
- Sesame
- Gluten
- Squid
- Crab
- Clam
NON-FOOD ALLERGENS:
- Aspergillus Fumigatus (Fungus)
- Alternaria Alternata (Fungus)
- Bermuda Grass (Grass)
- Timothy Grass (Grass)
- Cat’s Dander
- Dog’s Dander
- Blomia Tropicalis (Mite)
- D. Pteronyssinus (Mite)
- D. Farinae (Mite)
- American Cockroach
- German Cockroach
- Mugwart (Pollen)
- Ragweed (Pollen)
Blood IgE Test
- Allergy Blood tests (in-vitro immunoglobulin E antibody tests) are also available as a less invasive option where the body will not be directly exposed to the allergens.
- It is useful for those who should not or cannot undergo skin tests.
- Antibodies are produced when the blood sample comes into contact with the allergen. The test will then detect and measure the amount of allergen-specific antibodies in the blood.
– A Total IgE test is used to measure the total amount of IgE antibodies in the blood.
– A Specific IgE test measures how much IgE the body makes in response to a single allergen. A separate test is done for each allergen that may be causing the allergies. - Blood allergy tests can be ordered for single allergen, or for multiple allergens commonly responsible for certain conditions as well. For example – eczema panel, gastro panel, asthma panel, and comprehensive panel etc. All these can be discussed during medical consultation with a doctor.
- Blood test can be done at any time including while on long term medications such as antihistamines
- However, the result is not instant as the blood sample has to be sent to the lab for further analysis.
- Severity of allergy reaction towards each allergen tested will be reported on the laboratory result.
How can I cope if I’m diagnosed with Allergies?
Treatment plans may include multiple modalities, such as the usage of medications, immunotherapy, changes to your work or home environment, or dietary changes. This all depends on the patient’s reaction to allergen exposure.
Trigger Avoidance
The best way to prevent allergy symptoms and limit the need for allergy medicine is to avoid the allergens as much as possible. This includes removing the source of allergens from home and other places you spend time.
Medications
Treatment of symptoms:
There are many safe prescription and over-the-counter medicines to relieve allergy symptoms.
- For allergy symptoms related to nose and lungs
- steroid nasal spray, antihistamines, decongestants, or oral corticosteroid can be useful.
- For allergy symptoms related to skin – antihistamines and topical steroid cream can be useful.
- For allergy symptoms related to the eye – topical eye drops can be prescribed.
- For allergy symptoms related to gastrointestinal system – symptomatic treatment such as anti-vomiting, anti-diarrhea medicines, and medicines to reduce flatulence may be given.
- Anaphylaxis reaction – You may need to carry an emergency epinephrine treatment (epipen) with you at all times.
Treatment targeted at allergens/ Immunotherapy:
Immunotherapy is a treatment option for some allergy patients. The more popular option is sublingual immunotherapy (SLIT), where daily spray of medication under the tongue can be self-administered by patients.
SLIT has been in use since the 1980s and has a success rate of 80 percent especially for inhaled allergens such as house dust mites, pollen and animal fur.
In addition, SLIT reduces the risk of developing asthma and new allergies in the future, which will improve long term quality of life. Patients will become progressively less sensitive to that allergen as small doses of allergen are exposed gradually. This exposure improves tolerance to the substance and reduces symptoms. Reduction in the symptoms starts as early as 2-3 months from the start of treatment. It is recommended that treatment is continued for 3 years even if you do not have any more allergy symptoms. The improvement of symptoms may not last long if stopped prematurely.
In summary, allergic reactions can be varied in different individuals. Prompt and early testing is recommended to enable a clear discussion of treatment options available, with a better prognosis and improved quality of life in the long run.
Article contributed by Dr Goh Lit Ching.
She completed her Bachelor of Medicine and Bachelor of Surgery (MBBS) at the University of London in the United Kingdom. Her clinical interests include Family Medicine, Women’s Health and Preventative Care via Health Screening. Dr Goh is a firm believer of primary prevention and early detection improving disease outcome.
About DTAP
Established in 2005, DTAP (Dr. Tan & Partners) clinics, a pioneer of the GP plus, or “General Practice with Special Interest” model in Singapore, provides holistic and comprehensive medical care for everyone.
Photo by Towfiqu barbhuiya on Unsplash, by Tom Hermans on Unsplash, and by Allef Vinicius on Unsplash
