Allergy skin tests

Allergy skin tests are tests to find out if a substance, called an allergen, may cause an allergic response. A small amount of a suspected allergen is placed on or below the skin to see if a reaction develops.

There are three types of skin tests:

• Skin prick test. The health professional lightly scratches or pricks your child's skin with a drop of a liquid that contains a possible allergen.
• Intradermal test. Your child gets a shot with a small amount of the allergen solution.
• Skin patch test. A patch with the allergen solution is taped to your child's skin for 24 to 72 hours.

Allergy skin tests are done to find out what things you are allergic to.

For a skin prick test

The nurse will:

• Clean the test area (usually on your back or arm) with alcohol.
• Use a small device to scratch or prick your skin with drops of possible allergens. This allows some of the allergen to go into your skin.
• Check your skin after about 15 minutes for red, raised itchy areas called wheals. If a wheal forms, it means you are allergic to that allergen. This is called a positive reaction.

For an intradermal test

The nurse will:

• Clean the test area (usually on your back or arm) with alcohol.
• Inject the allergen solution into the skin.
• Check your skin after about 15 minutes for red, raised itchy areas called wheals. If a wheal forms, it means you are allergic to that allergen. This is called a positive reaction.

Be sure to tell your doctor about all the medicines you take. You may need to stop taking some medicines such as antihistamines for a few days before you have an allergy skin test.