Intradermal Injection

Introduction and Purpose of Intradermal Injections

An intradermal injection involves administering medication directly into the dermal layer of the skin, located just beneath the epidermis. Because blood supply in the dermis is extremely limited and drug absorption occurs very slowly, this route is rarely used for systemic drug delivery. Instead, primary healthcare providers utilize intradermal routes primarily for diagnostic testing.

• Tuberculin testing: Screening for exposure to Mycobacterium tuberculosis using the Mantoux method.
• Allergy skin testing: Identifying specific environmental or food allergens by observing local immune responses.
• Local anesthesia: Desensitizing a small patch of skin prior to minor procedures or deeper needle insertions.

Anatomical Sites and Skin Layers

Successful delivery requires placing the needle strictly between the epidermal and subcutaneous layers. The preferred sites offer good visibility, minimal hair, and low pigmentation to ensure clear reading of skin reactions.

• Volar surface of the forearm: The classic, most common site chosen for tuberculosis screening and allergy testing.
• Upper back: Frequently utilized for extensive allergy panel testing when arm space is insufficient.
• Upper chest: An alternative site occasionally used based on institutional protocol or patient skin integrity.

Equipment and Material Selection

Using proper equipment ensures accurate dosing and minimizes tissue trauma. The physical characteristics of the needle and syringe are tailored specifically for shallow skin penetration.

Step-by-Step Procedure for Administration

Administering an intradermal injection demands steady hands and strict adherence to aseptic technique.

1. Perform hand hygiene and put on clean gloves.
2. Cleanse the selected skin site with an alcohol swab using a firm circular motion outward, then allow it to dry completely.
3. Pull the skin taut at the site using the non-dominant hand to provide a firm surface.
4. Hold the syringe in the dominant hand with the needle bevel facing upward.
5. Insert the needle at a 5 to 15-degree angle to the skin surface.
6. Advance the needle approximately 3 millimeters into the epidermis so the bevel is visible through the skin.
7. Inject the medication slowly; a distinct bleb or wheal should form on the skin surface.
8. Withdraw the needle at the exact angle of insertion and activate safety devices without massaging the site.

Reading and Interpreting Results

Evaluating skin tests requires precise timing and clinical measurement. For a tuberculin skin test, the patient must return to the clinic within 48 to 72 hours for evaluation.

When assessing the site, the nurse palpates the area to feel for induration—a hard, raised, palpable thickening of the skin—rather than just measuring surface redness or erythema. A transparent ruler is used to measure the diameter of the induration transverse to the long axis of the arm. Documenting only the size of the raised hard area, measured in millimeters, ensures accurate clinical interpretation according to established public health guidelines.

Potential Complications and Nursing Interventions

While generally safe, intradermal injections carry risks of local adverse reactions and procedural errors.

• Anaphylaxis: Severe systemic allergic reaction occurring rapidly after allergen testing; requires immediate administration of epinephrine and emergency support.
• Necrosis or ulceration: Tissue breakdown at the site due to highly irritating medications or improper deep placement.
• Infection: Localized bacterial entry managed by keeping the site clean and monitoring for spreading warmth or purulent drainage.
• Failure to form a bleb: Indicates the needle is too deep in subcutaneous tissue; the nurse must withdraw the needle and restart at a new site.

Documentation and Patient Education

Accurate records and clear instructions protect patient safety and ensure continuity of care. Documentation must include the exact medication name, dose, specific anatomical site, date, time, and nurse signature. For diagnostic tests, nurses must record the return appointment date and time for reading results.

Patients receive instructions to keep the injection site uncovered, clean, and dry. They must be warned not to scratch, rub, or apply creams to the bleb. Education also emphasizes the necessity of returning for the follow-up evaluation and reporting any signs of spreading rash, breathing difficulty, or dizziness immediately.