Skin testing for allergies is the most common way to determine allergies but not everyone is a great candidate for scratch, patch, or intradermal tests. If an allergist cannot perform skin testing on a patient then they will do an allergy blood test.
When you come into contact with something that triggers your allergies, your body produces antibodies against it. During an allergy blood test a small amount of your blood will be drawn and then sent to a lab. The lab will determine the amount of specific allergen antibodies that are present in your blood, this will tell them what you are allergic to.
An allergist will do a blood test in certain circumstances, including the below:
- The patient has previously had a severe reaction to a skin test, in extreme cases this is called anaphylaxis.
- The patient is taking medications that will interfere with skin testing results, including steroids, some antidepressants, and antihistamines.
- The patient has a heart condition.
- The patient has serious asthma.
- The patient has a skin condition such as psoriasis or eczema.
Allergy blood testing has negative and positives attributes.
Here are some of the good things about using blood testing to determine your allergies:
- Allergy blood testing can be done at any time, regardless of medications that you are taking
- This type of testing only requires one needle as opposed to scratch or prick testing which involves multiple needles- one per allergen. If you are wary of needle then blood testing might be the way to go.
Here are some of the downsides of allergy blood testing:
- Blood testing is a more expensive process since the results must be sent away to be evaluated by a lab.
- For this same reason, the results of a blood test will take longer to receive. It will take longer to find out what you are allergic to.