Bleomycin and 5-fluorouracil injections

Intralesional bleomycin and 5-fluorouracil (5-FU) are injected directly into the scar. This is an off-label use of both drugs, explored mainly where conventional treatments — corticosteroids, silicone gel, cryosurgery — have already failed.

How effective are they?

Several small studies and case series have shown that these injections can flatten keloids and hypertrophic scars, reduce pain and itching, and improve cosmetic appearance. Reported improvement rates range from 50% to 95%, with a low recurrence rate compared with other treatments.

How they work

Both are cytotoxic agents. They induce DNA strand breaks in fibroblasts, suppress collagen synthesis, and cause the death of fibroblasts and endothelial cells within the scar. That makes them useful against fibroproliferative conditions such as keloids.

How they are given

Bleomycin — typically 0.1–0.5ml of solution at 1.5 IU/ml, injected into the scar monthly for two to six sessions depending on response. Often combined with a local anaesthetic to reduce injection pain.

5-fluorouracil — typically 0.5–2ml of 50mg/ml solution per session, injected into the scar weekly for no more than twelve weeks. Often combined with low-dose intralesional steroids.

Side effects

Most are local to the injection site:

• Pain at the injection site
• Skin ulceration
• Lightening or darkening of the skin
• Tissue necrosis, which is rare and usually dose-dependent

The risk of systemic toxicity is minimal at these small local doses, but caution applies, particularly in children and in pregnancy.