Alopecia areata (AA) is an autoimmune condition where the body’s immune system mistakenly attacks the hair follicles, leading to non-scarring, patchy hair loss, most commonly on the scalp. While some patches may resolve spontaneously, others require medical intervention. For patients with limited, patchy involvement, intralesional triamcinolone acetonide (TAC) is the most frequently utilized and effective localized therapy. Triamcinolone is a corticosteroid that, when injected directly into the affected skin, suppresses the localized immune response against the hair follicles, allowing for hair recovery.
Professional Administration Requirements
This treatment is a specialized medical procedure that requires a qualified healthcare professional, typically a dermatologist, to administer the injections safely and effectively. Improper injection carries risks of infection, incorrect dosing, and tissue damage. Before the procedure, the clinician confirms the diagnosis and assesses the extent of hair loss, which is generally most suitable for areas covering less than 50% of the scalp. The assessment also checks for local skin infections or other contraindications. Informed consent requires a detailed discussion about the procedure, expected outcomes, and potential side effects.
Intralesional Injection Technique
The procedure involves injecting small, precise amounts of the corticosteroid suspension directly into the skin lesions. For the scalp, the concentration of triamcinolone acetonide most often used ranges from 5 to 10 milligrams per milliliter (mg/mL), though 5 mg/mL is preferred to balance efficacy and side effects. When treating sensitive areas like the face or eyebrows, a lower concentration of 2.5 mg/mL is selected to minimize the risk of skin thinning. The clinician uses a very fine needle, such as a 30-gauge needle, to target the specific skin layers.
The medication must be deposited into the upper subcutaneous tissue or the deep dermis, where the hair follicles are located. A maximum volume of 0.05 to 0.1 milliliters is used per injection site. These injections are spaced in a grid-like pattern, usually about 0.5 to 1 centimeter apart, ensuring even distribution across the bald patch. To manage the mild pain associated with multiple injections, the dermatologist may apply a topical anesthetic cream or use a cooling spray beforehand.
Response and Treatment Schedule
Patients who respond typically begin to see initial signs of hair regrowth within four to eight weeks following the first or second session. The new hairs often appear fine and light at first, gradually thickening and darkening to match the surrounding hair. Treatment effectiveness is highest in patients with smaller patches of hair loss and a shorter duration of the current episode. The standard protocol involves repeating the injection session every four to six weeks, based on the patient’s response. If no satisfactory hair regrowth occurs after three to six months of continuous treatment, injections are usually discontinued, or stopped once the affected area achieves cosmetically acceptable hair density.
Adverse Effects Profile
The most common side effects are localized reactions at the site of administration, which are usually temporary. The primary concern is cutaneous atrophy, presenting as a temporary thinning or indentation of the skin. This occurs when the steroid affects the underlying fat tissue and is more likely with higher concentrations or excessive volume. Another frequent side effect is temporary hypopigmentation, appearing as a lightening of the skin color. Both atrophy and hypopigmentation are reversible and improve over several months once injections are stopped. Other immediate reactions include pain, bruising, or minor bleeding; systemic side effects are rare, though prolonged use near the eyes carries a risk of affecting intraocular pressure or causing cataracts.