Intralesional injection delivers medication directly into a lesion, placing a high concentration of the active agent exactly where it’s needed while minimizing systemic absorption and side effects. It’s a targeted approach that works well for a number of conditions where topical application or oral medication is either insufficient or inappropriate.
Common uses
Inflamed epidermoid cysts respond rapidly to intralesional corticosteroid injection placed directly into the cyst cavity. Most patients notice significant reduction in inflammation and pain within 24 to 48 hours. The injection doesn’t remove the cyst — the sac remains — but it resolves the acute flare quickly. Definitive removal can be planned once the inflammation has fully settled.
Keloids and hypertrophic scars respond to serial intralesional triamcinolone injections, which reduce the collagen overproduction that creates excessive scar tissue. Results develop over weeks to months with a series of injections spaced four to six weeks apart. Some keloids respond well; others partially. For larger keloids, injection is often combined with other approaches.
Alopecia areata — patchy hair loss from an autoimmune attack on hair follicles — responds to intralesional corticosteroid injections in the affected scalp patches. Regrowth typically begins four to eight weeks after injection. For localized patches, this is often the first-line treatment we recommend.
Resistant warts that haven’t responded to cryotherapy are sometimes treated with intralesional injection of Candida antigen or bleomycin. The mechanism involves stimulating a local and sometimes systemic immune response against HPV, which can clear not only the injected wart but satellite warts elsewhere.
Cystic and nodular acne lesions that are large and painful can be injected with dilute triamcinolone for rapid reduction. A cystic acne lesion that might take weeks to resolve on its own typically flattens significantly within 24 to 48 hours of injection.
Frequently asked questions
Is it painful?
The injection produces a brief sharp sensation that most patients describe as very manageable. For sensitive areas or patients with low pain tolerance, a small amount of topical or local anesthetic can be used beforehand.
Are there risks?
Corticosteroid injections carry a small risk of skin atrophy — a depression in the skin at the injection site — particularly if a high dose is injected superficially or into thin skin. This usually resolves over months. Using the appropriate concentration and technique minimizes this risk, which is why the injection matters as much as the medication.
How many injections will I need?
It depends on the condition. Inflamed cysts often respond to a single injection. Keloids and alopecia areata typically require a series of sessions spaced several weeks apart. We assess response after each treatment and adjust accordingly.