Intradermal tests

What it is

They are used to detect immediate allergic sensitisation (IgE-mediated) when skin prick tests are negative or inconclusive.

Your care

• A specialist diagnostic test.
• Performed as part of an in-depth allergy work-up.
• A second-line test, used after skin prick tests.
• Covered in line with the applicable medical regulations.

Where does the test take place?

👉 Only ever at the practice, under strict medical supervision.

The test is never carried out outside a safe medical setting.

What is the test for?

Intradermal tests are used to:

• Detect an immediate allergy not shown up by skin prick tests.
• Investigate certain drug allergies.
• Complete the work-up before allergen desensitisation.
• Refine the diagnosis when clinical suspicion is high.

⚠ They must be interpreted with particular care.

Indications

• Suspected immediate allergy with negative skin prick tests.
• Drug allergies (antibiotics, anaesthetics, venoms).
• Work-up before allergen immunotherapy.
• Unexplained reactions that suggest an allergy.
• Urticaria or suspected systemic reactions.

What happens

1. The skin is disinfected (usually on the forearm).
2. A diluted allergen is injected into the skin.
3. A small initial bleb forms.
4. Results are read after 15 to 20 minutes.
5. Comparison with positive and negative controls.

⏱ Total time: about 30 to 45 minutes.

Results

• Results are available immediately.
• Positive reaction = a significant increase in the size of the wheal, with redness (erythema).
• Standardised reading according to precise medical criteria.
• Results are interpreted in the light of your symptoms.

Safety

• ✔ The test is carried out under medical supervision.
• ✔ Local reactions are possible (itching, redness).
• ✔ Generalised reactions are rare but possible.
• ✔ Emergency equipment is always on hand.

⚠ It is a more sensitive test, so it is monitored more closely than the skin prick test.