Intracutane

Intracutane, commonly described as intracutaneous or intradermal injection, refers to the administration of substances into the dermal layer of the skin, the tissue beneath the epidermis. The technique targets a shallow depth, typically about 1 to 2 millimeters, using a fine-gauge needle (generally 27–30 gauge) inserted at a shallow angle to form a small wheal or bleb. The dermis contains abundant immune cells, including Langerhans cells, which makes this route particularly useful for diagnostic tests and certain vaccines.

Common indications include allergy skin testing, where intradermal injections assess hypersensitivity to specific allergens, and the tuberculin skin test (Mantoux), which uses intradermal administration of tuberculin. Although most vaccines are given intramuscularly, intradermal administration has been used for some vaccines, most notably the Bacillus Calmette–Guérin (BCG) vaccine in certain settings, and in some influenza vaccine formats.

Advantages of the intradermal route include strong local immune activation and the requirement for smaller volumes. Limitations include technique sensitivity and a higher likelihood of local reactions such as redness, swelling, itching, or induration. It is generally less suitable for drugs that require rapid systemic distribution, and improper technique can lead to subcutaneous deposition instead of dermal delivery.

In practice, intracutaneous and intradermal are often used interchangeably, though some clinicians reserve intracutaneous for historical references and intradermal for modern terminology. Proper aseptic technique and appropriate patient selection are essential.