Managing an allergy starts with knowing what’s causing it. Skin testing is one of the main ways to find out, and it can check for several possible allergens at once.
The three kinds of skin test
Scratch (prick) test
Usually the first test done. A drop of liquid containing each allergen is placed on the skin, which is then lightly pricked with a small needle. Several are laid out in a grid, normally on the forearm or back, and the skin is watched for a reaction over about fifteen to twenty minutes. It’s quick, and more startling than painful.
Patch test
An adhesive patch coated with a specific substance is worn for around 48 hours. Because it stays on, it’s the test that picks up delayed reactions — useful for contact allergies affecting the skin.
Intradermal (injection) test
A small amount of allergen is injected just beneath the surface of the skin rather than pricked into it. It’s more sensitive than the scratch test and is used when a scratch test was negative but suspicion remains.
Before a test
Antihistamines suppress the reaction the test is looking for, so they usually need stopping several days beforehand. We’ll tell you exactly which medicines to hold and for how long when the test is arranged — don’t stop anything without checking first.
What the results mean
A positive skin test shows sensitivity, which isn’t quite the same as an allergy that matters in daily life. Results are read alongside your child’s history — what happened, when, and how often. That’s why the story you give us is as important as the test itself.
If your child has reacted to a food, Food Allergies covers what to watch for and what to do.