Intralesional corticosteroid injections, often called “steroid shots,” are a common medical treatment for various inflammatory scalp conditions. These injections deliver a precise dose of a potent anti-inflammatory medication, such as triamcinolone acetonide, directly into the affected skin layer. This localized delivery is highly effective for calming the immune response that drives conditions like alopecia areata, lichen planopilaris, and certain types of scalp psoriasis. The goal is to reduce inflammation at the source, allowing hair follicles or skin tissue to recover. While this targeted approach minimizes body-wide exposure, localized side effects can still occur, which patients should understand before starting treatment.
Immediate and Acute Injection Site Reactions
The most common side effects occur immediately following the procedure and are typically temporary. Patients frequently report a brief, sharp stinging or burning sensation during the injection, which quickly subsides once the needle is withdrawn. Following the procedure, minor localized effects are common, such as pinpoint bleeding, slight bruising, or temporary redness (erythema) at the injection sites. These reactions are a normal consequence of needle puncture and usually fade completely within a few hours to a couple of days. Mild, temporary swelling or a feeling of tension can also occur as the medication disperses under the skin.
Structural Changes to Scalp Tissue
More persistent side effects involve visible changes to the physical structure and appearance of the scalp. One recognized structural effect is dermal or subcutaneous atrophy, which presents as a slight depression or denting in the skin. This occurs because the corticosteroid causes a localized breakdown of fat and collagen tissue beneath the skin’s surface. The risk of these indentations increases with higher steroid concentrations or repeated injections into the same spot. While tissue thinning can be concerning, it is often reversible; the skin typically starts to fill back in over several months, though complete resolution may take a year or more.
Another common localized effect is hypopigmentation, a lightening or loss of color in the skin at the injection site. This is caused by the steroid interfering with melanocytes, the cells responsible for producing skin pigment. This effect is more noticeable in individuals with darker skin tones and can take many months to resolve, occasionally being permanent. Telangiectasia, the formation of small, dilated blood vessels near the skin’s surface, can also occur, appearing as fine, reddish spider veins in the treated area.
Rare Systemic Effects and Hormonal Impact
Because the medication is injected directly into the scalp, the amount entering the bloodstream is usually small, making systemic side effects rare. If a large area is treated or high doses are used frequently, the absorbed steroid may impact the body’s natural hormone balance. This can potentially lead to a temporary suppression of the hypothalamic-pituitary-adrenal (HPA) axis, which regulates the body’s natural cortisol production. Signs of this suppression might include fatigue or weakness, though this is uncommon with standard dosing. Patients with diabetes should note that the absorbed steroid may cause a temporary elevation in blood sugar levels for a few days.
The risk of infection at the injection site is very low when the procedure is performed under sterile conditions by a qualified provider. A localized allergic reaction to the specific corticosteroid compound or the suspension fluid is also possible, though this is uncommon.
Expected Duration and When to Consult a Doctor
The timeline for side effect resolution depends on the specific reaction experienced. Acute effects like pain, bruising, and minor swelling typically resolve quickly, usually within 24 to 72 hours of the procedure. Structural changes, such as skin atrophy and hypopigmentation, follow a much slower course and may take six to twelve months or longer to show significant improvement.
It is important to contact the prescribing physician immediately if any signs of infection develop after the injection. Warning signs include:
- Pain that becomes severe or worsens after the first few days.
- Spreading redness beyond the immediate injection site.
- Warmth.
- Fever.
- The presence of pus.
Individuals who experience sudden or severe systemic symptoms, such as rapid heartbeat, significant mood disturbance, or unusual weakness, should also seek prompt medical attention.