Allergy testing can include a skin prick or scratch test, patch testing, challenge testing or an IgE blood test (RAST). The right test for you depends on your allergy symptoms and the types of allergens you might be allergic to. Allergies to cats, dogs, dust and mould are very common in the wintertime. Various pollens are more common in the summer, and allergies to these are also known as hayfever.
The best way to figure out the right test for you is to contact your allergist, such as us at Holistic Allergy. After an initial consultation, we will guide you and advise you on the best type of test to reach a diagnosis.
But say that you already have an allergy test scheduled.
Next, you must pay attention to the instructions provided by your allergist on the dos and don’ts on the days before your test. Ignoring these can lead to either an indeterminate or a false negative or false positive result. In some cases, you may even be asked to reschedule the test at your own cost.
What you shouldn’t do before an allergy test
To ensure the accuracy of your test results, please bear in mind the following:
Medication restriction
Antihistamines
Antihistamines are perhaps the most important medication to tell your allergist about.
While most antihistamines can be purchased over the counter, this medication can negatively affect your test results. This can result in false negatives. This is because it helps dampen your body’s response to allergens it gets exposed to.
You must therefore stop taking antihistamines at least five (5) days before your scheduled test.
Antihistamines include the following medication:
- Cinnarizine
- Cyclizine
- Promethazine
- Alimemazine
- Chlorphenamine/ Piriton
- Acrivastine
- Bilastine
- Cetirizine/ Piriteze/ Zyrtek/ Benadryl
- Desloratadine
- Loratadine/ Claritin/ Alavert
- Fexofenadine/ Allegra/ Telfast/ Mucinex/ Almerg/ Treathay
- Levocetirizine
- Mizolastine
Of the above, the ones in bold are the most common, also known by their brand names.
source: BNF
Antihistamine medication can also be split into sedating or non-sedating antihistamines. Regardless, all of the above can dampen the immune system response. If safe, you should stop them at least 5 days prior to your allergy test. For more personalized advice, contact your allergist and give them a list of all the medication you are on.
NOTE: Some cough mixtures may also contain certain antihistamines. If you are currently taking a cough syrup, please check the label or ask us if you are unsure.
Tricyclic Antidepressants
These include medication such as Amitriptyline that could also suppress your body’s immune response to the test allergen. The effect is usually not as pronounced as with antihistamines however, and it may be more tricky to stop. It’s therefore important to get the all clear from your GP before holding this medication, as you may otherwise have withdrawal effects.
Heartburn medication
H2 blockers such as Ranitidine, Famotidine, Cimetidine and Nizatidine should also be stopped at least 48 hours before allergy testing. These reduce acid secretion in the stomach, but also work by inhibiting the action of histamine. H2 blockers can therefore interfere with allergy skin testing, which relies on the skin’s reaction to histamine
Other herbal remedies/ supplements
Also, inform your allergist about any other herbal remedies or over the counter medication and supplements you are taking.
What to do on the day of the test
The skin prick test usually takes about 30 minutes and you will be informed of the results on the day.
Time
Ensuring you arrive on time lets you settle down for a few minutes before starting the test. This is important so you don’t feel like you are in a rush and to allow your blood pressure and heart rate to settle down.
Clothing
Wear comfortable, loose-fitting clothing. This is so your arms can be accessible for the skin prick testing.
For patch testing, your back will need to be accessible so make sure you wear a top that can be removed easily.
After the test: What to expect
Immediate results: Skin prick tests are great because they are accurate and quick to do when they are done by a professional. You also get the results within 15-20 minutes.
Your allergist will interpret these results and discuss them with you.
Post test care: This will vary from person to person. There might be a local reaction such as redness or swelling at the test site which may persist for a few hours. This is usually mild and should not be spreading after the test has concluded.
Once the test is done, you can restart your antihistamine medication. The same applies to other medications that you might have stopped in preparation for the test.
Follow up: Based on the results, your allergist will discuss the next steps, which may include further testing, starting an allergy treatment plan, or making lifestyle or dietary changes. We usually have at least one follow up to monitor the progress and to check whether the management plan has helped your symptoms. More complicated situations, or an indeterminate skin prick test may require further testing and future follow up sessions too.
In conclusion, preparing for an allergy test can make a significant difference in the accuracy of the results. By following these specific tips and adhering to your allergist’s advice, you can approach your allergy test with confidence, knowing that you’re well-prepared and you will get an accurate diagnosis.
Essentially, attending an allergy test clinic can be a “one stop” shop that involves a consultation, tests on the day and a management plan to take home with you.
