Parenteral medications injected into the dermis are known as intradermal (ID) injections. Certain medications are indicated for this route because absorption via dermal tissue is slow. The nurse must be able to accurately perform the steps for administering ID injections, including selecting an appropriate injection site and needle size, and demonstrating proper technique. This section will provide you with the knowledge to safely administer medications via the ID route.
Medications administered via the ID route are injected into the dermis, just below the epidermis. Of all the parenteral routes, the ID route has the most prolonged absorption time. This is because there are fewer blood vessels and no muscle tissue available to distribute the medications. To ensure the medication is administered into the dermis, careful consideration must be given when selecting an appropriate anatomical site for the ID injection.
When administering medications via the ID route, it is important to select an appropriate anatomical site. The most commonly used sites include the anterior surface of the forearm, posterior surface of the upper arm, the upper back and under the scapula, and upper chest (Figure 12.25). When selecting an injection site, the site should be free of lesions, rashes, moles, scars, sores, and veins.
Figure 12.25 This illustration shows the anatomical sites appropriate for administering intradermal injections. (attribution: Copyright Rice University, OpenStax, under CC BY 4.0 license)
Intradermal injections have a prolonged absorption rate; therefore, this route is not appropriate for all medications. The ID route is preferred when the patient’s reaction to the medication needs to be observed, such as with Botox injections, allergy testing, or tuberculosis testing. It is also the preferred route for injecting steroids directly into lesions and when providing local anesthetics.
Botulinum toxin (Botox) is commonly used for facial rejuvenation and anti-aging. Botox is typically injected into the forehead, between the eyebrows, and around the periorbital region. Typically, it is injected between 1 and 4 mm deep, depending on the injection site. When administering Botox, injections that are too superficial or too deep may lead to the drug being injected into the wrong muscle, which may cause undesired outcomes. Complications of Botox include mild bruising, brow or eyelid ptosis (drooping eyelid), dry skin, allergic reaction, injection site pain, headache, or unwanted cosmetic results. To reduce the risk of bruising, the nurse should ensure that makeup is removed, there is adequate lighting, and the skin is gently stretched to enhance visualization of the superficial blood vessels. Post-injection, patients should be instructed to apply ice and pressure to the injection site, avoid vigorous exercise, remain in the upright position for several hours post-injection, and avoid sleeping on their stomachs.
Intradermal allergy testing is used to determine if an individual is allergic to a particular allergen. To perform this skin test, the nurse injects a small amount of the allergen into the skin and then monitors the individual for a reaction at the site (Figure 12.26). The nurse marks the injection sites with a number to indicate which allergen was placed at each site. By doing so, the results of the test can be interpreted more easily and correctly. If the individual is not allergic to the allergen, then no skin changes will be noted. If the individual is allergic to the allergen, a red, raised wheal will be present. In addition, the individual may experience itching, skin rash, stuffy nose, red watery eyes, or possible anaphylaxis. Therefore, it is critical to have an emergency kit nearby to treat potential allergies, such as epinephrine and antihistamine injections.
Figure 12.26 Allergy skin tests numerically identify the allergens tested. (credit: “Pricktest, 2020.jpg” by Axel Pettersson/Wikimedia Commons, CC BY 4.0)
Nurse: Rafael, RN
Clinical setting: Outpatient allergy clinic
Years in practice: 9
Facility location: Eastern United States
I work in an outpatient allergy clinic where we test patients for possible allergies by placing small quantities of different allergens intradermally. Most of our patients are referred to us because of a suspected allergy; therefore, we are always prepared to intervene if a reaction occurs during the allergy skin test.
One morning, I was performing the test on Ms. Sampson, a 54-year-old patient, who had a reaction to the test. I had placed several of the samples (grass, pollen, pet dander, mold) without any responses noted to the skin. I then proceeded to administer the food samples (milk, wheat, peanuts, eggs). Shortly after administering the food samples, Ms. Sampson started complaining of watery eyes and itching to the surface of the skin where the samples were placed. I assessed the patient’s arm and noticed a raised wheel where the wheat test was placed. Per protocol, I had identified the sites where the samples were placed with corresponding numbers, so there was no doubt that the wheat had caused the reaction.
I grabbed the emergency kit just in case the patient went into anaphylaxis; however, thankfully, it was not needed. To help relieve the symptoms, I gave Ms. Sampson a 25 mg diphenhydramine (Benadryl) tablet, applied hydrocortisone cream to the test site, and placed a cool cloth on the site. I have seen my fair share of anaphylaxis reactions so I am always cautious about ensuring that the emergency kit is nearby.
The Mantoux tuberculin skin test (TST) is used to diagnose latent tuberculosis (TB). A small amount (0.1 mL) of purified protein derivative (PPD) is placed directly into the inner surface of the forearm, approximately 2 to 4 in (5 to 10 cm) below the elbow. When placed correctly, it should produce a visible elevation of the skin (also known as a wheal ). The results of the test must be read within forty-eight to seventy-two hours of administering the test. If the test is not read within seventy-two hours, the test must be repeated. When assessing the results, measure the induration (firm swelling) of the wheal in millimeters, not erythema (redness). To assess the induration, visually inspect and gently palpate the test site. To measure the diameter of the induration, place the “0” of the ruler on the inside left edge of the induration and read the ruler on the inside right edge of the induration (Figure 12.27). Document the measurement of the induration, recording no induration as 0 mm. The results of the TST are interpreted using the diameter of the induration and the person’s risk factors.
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Figure 12.27 TB skin tests measure induration, not erythema. (credit: Centers for Disease Control and Prevention/Public Health Image Library, Public Domain)
Steroids may be injected intradermally, directly into a skin lesion. Intralesional steroid injections are commonly used to treat skin diseases, such as keloids, alopecia areata, and circumscribed plaques of dermatitis. Triamcinolone acetonide (Kenalog), dexamethasone ( Decadron ), betamethasone ( Betaderm ), and methylprednisolone sodium succinate (Solu-Medrol) are the most commonly used intralesional steroids. Intralesional steroids should not be injected into active skin infections or if the patient has a known allergy to the medication. Potential side effects of intralesional steroids include pain, bleeding, bruising, infection, contact allergic dermatitis, impaired wound healing, abscess, lipoatrophy , and pigmentation changes.
Local anesthetics (lidocaine [Xylocaine], bupivacaine [Marcaine]), may be administered intradermally to numb the skin prior to a procedure. Unlike general anesthetics, local anesthetics do not require a loss of consciousness. These medications work by blocking the signals at the nerve endings of the skin. Typical onset of action for lidocaine is usually one to three minutes, with a duration of thirty minutes to two hours. On the other hand, the typical onset of action for bupivacaine may be up to ten minutes but the duration may last up to three hours.
Safe administration of ID injections requires following proper technique. When administering ID injections, it is important to select an appropriate site for administration. After selecting the site, the nurse cleans the skin with an alcohol swab to help prevent pathogens from being introduced into the tissue by the needle . The nurse allows the skin to dry completely so that the alcohol is not introduced into the tissue. Holding the syringe at a 5- to 15-degree angle from the site with the bevel up allows for smooth introduction of the needle into the dermis (see Figure 12.10). The nurse inserts the needle about 0.25 in (6.4 mm) into the skin and slowly injects the medication. A small medication-filled bubble called a wheal or a “bleb” will appear at the injection site if administered correctly (Figure 12.28). Aspiration is not necessary because the dermis contains few blood vessels. After administration, the nurse removes the needle at the same angle in which it was introduced into the skin, engages the needle safety device, and discards the syringe in a sharps container. Do not massage the area after injection because this may spread the medication into the underlying subcutaneous tissue.
Figure 12.28 The presence of a wheal is often a visible sign of an underlying immune response or inflammatory reaction. (credit: Centers for Disease Control and Prevention/Public Health Image Library, Public Domain)
You can view how to administer an intradermal medication in this video demonstration.
