Allergy skin tests

allergy skin test · skin prick test · scratch test · allergy testing

Drops of allergen solutions are placed on the skin of your forearm or back, and the skin is lightly scratched. After 15 to 20 minutes, the doctor checks where redness and bumps appear.

For hay fever, rashes, asthma, or reactions to food or insect stings, to find out exactly what you are allergic to.

⏱ Duration: usually 30 to 60 minutes with waiting; results right away

Be sure to tell your doctor

All your medicines, especially allergy pills, steroids, and blood pressure pills
If you ever had a severe allergic reaction or swelling
If your allergy or asthma is flaring up now
If you are pregnant
Any skin conditions on your arms or back

How to prepare

Allergy medicines. They can hide the result. Do not stop them on your own. Tell your doctor. They will decide what to stop and how many days before.
Health. Tests are usually done when allergies are not flaring. If you have strong allergy symptoms or a cold now, they are postponed.
Skin. On the test day, do not put cream on your arms or back.
Clothing. Wear a sleeve that is easy to pull up, or clothes that let you show your back.

What to bring

Your referral
A list of your medicines
Notes on past reactions and allergy tests

How it goes

The doctor decides which allergens to test
The skin is wiped and marked with a pen
A drop of allergen goes on each mark
Through the drop, the skin is lightly scratched or pricked with a single-use lancet
You wait 15 to 20 minutes without touching the skin
The doctor measures the bumps and writes down the results

What you'll feel

Light tingling from the scratch
Where there is a reaction: itching, redness, and a bump like a mosquito bite

Afterwards

The itching and bumps usually go away in a few hours
Do not scratch the skin
The doctor explains the results right away

Contact a doctor straight away if

Swelling of the face or lips, trouble breathing, or strong weakness after the tests: call emergency services
A strong rash all over the body: see a doctor right away

Common questions

Can children have skin tests?

Yes, usually from a few years of age. The allergist decides the age and method.

Why should I not take allergy pills before?

They block the skin reaction, so the tests may show nothing. Your doctor will tell you how many days before to stop them.