Route · Injection

Intralesional 5-fluorouracil: the combination ranked first; alone it was not superior

In a 2026 network meta-analysis of 24 randomised trials, triamcinolone combined with 5-FU gave the most favourable balance of efficacy and recurrence reduction. But the same analysis wrote that 5-FU monotherapy, like bleomycin, gave intermediate outcomes without statistical superiority. In a 66-patient double-blind trial in Nepal, the combination beat steroid alone significantly on height, scar scores and satisfaction, with fewer complications. But that trial was single-centre, and recurrence could not be assessed.

Last checked Oct 2, 2026

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What it is: Injecting 5-fluorouracil, a chemotherapy drug, directly into a keloid or hypertrophic scar.
What it is used for: For keloids and hypertrophic scars. Usually given together with a steroid.
How it is said to work: It is described as suppressing the proliferation of the fibroblasts that build scar.

There are no numbers and no citations in this box. What has been established, and how far, is below.

At a glance

Session length: 5–15 min
Pain: Painful
Downtime: 0–2 days
Sessions: 6 sessionsReported in a trialThe 66-patient trial above injected every two weeks until week 10 and evaluated at week 12.
How long it lasts: Not applicable
Relative cost: Lower
How well established: Moderate evidence

“Reported in a trial” means a number a study on this page actually reported. “Typical range” is not a measured value but roughly how it is usually done, and it varies by clinic and by person.

Cost is not an amount but a band: where this procedure falls when the ones on this site are lined up per session, or per area treated. Real prices differ several-fold by clinic and by how much is treated, so they are not given here. Surgery is measured on a different scale and cannot be compared with this band.

This is not how large the effect is but how well confirmed it is. It shows the highest grade among the findings on this page.

Korean classification Being checkedThe regulatory class has not yet been confirmed against a primary document. It will be filled in once it is.

Intralesional 5-fluorouracil means injecting 5-FU, a chemotherapy drug, directly into a keloid or hypertrophic scar. It is usually given together with intralesional corticosteroid.

That 'together' is the point of this page.

This site asks on every page: what was it added on top of? Usually we ask because there is no answer. Here there is one — and it splits in two.

used with a steroid — the most consistent position in an analysis of 24 trials
used alone — no statistical superiority in the same analysis

This site writes both sentences on one page, and splits the badge in two as well.

And it notes that in keloids, response and recurrence are different questions.

In the same analysis, botulinum toxin A ranked highest in treatment response but did not significantly reduce recurrence risk. This site has a separate keloid entry on the botulinum toxin page, titled 'symptoms, not shape'. It is the same kind of story.

In keloids, 'it got better' can mean two things.

is it flat now
does it stay down

Answering the second needs long follow-up, and we did not find enough of it. The 66-patient trial below wrote that limitation itself — recurrence could not be assessed.

This site writes the most important thing about scars first. With keloids, not forming one is far better placed than treating one that has formed. And if you tend to keloid, that enters the decision about every cosmetic procedure and operation. See the scars page alongside.

This site does not deal in prices, clinics or reviews.

What is established

Moderate evidence

Added to a steroid it beat the steroid alone — and the combination ranked first across 24 trials

A randomised double-blind trial in Skin Health Dis (2024) and a network meta-analysis in Aesthet Surg J (2026).

The 66-patient trial first.

66 cases of keloids and hypertrophic scars were randomly allocated to two groups. Parallel-group, double-blinded, at one hospital in Nepal.

group A — triamcinolone acetonide alone
group B — a combination of triamcinolone acetonide and 5-fluorouracil
injections every 2 weeks until 10 weeks, with final evaluation at 12 weeks

The results.

all parameters improved at every follow-up visit in both groups
a reduction of 50% or more in height, reductions in the Vancouver Scar Scale and POSAS scores, and good-to-excellent subjective improvement reported by both patients and observer — all significantly greater in the combination group than with the steroid alone
the response was faster, and complications were fewer in the combination group
the paper's limitations — single-centre, no long-term follow-up, and recurrence could not be assessed

Now the network meta-analysis.

Searching through May 2025, it pooled 24 randomised trials comparing two or more intralesional treatments in a frequentist random-effects network meta-analysis, integrating direct and indirect comparisons.

triamcinolone combined with 5-FU achieved the most consistent improvements in efficacy and recurrence control
botulinum toxin A ranked highest in treatment response but did not significantly reduce recurrence risk
verapamil was significantly less effective than triamcinolone
bleomycin and 5-FU monotherapies provided intermediate outcomes without statistical superiority
the authors' conclusion — it supports consideration of combination regimens, and underscores the need for further well-designed head-to-head trials with standardised endpoints
the level of evidence the paper gives itself — 3 (therapeutic)

How to read it.

First, the control was another treatment, not placebo. The comparator in the 66-patient trial was steroid alone. This site records that as an active control. Not being placebo-controlled, the sentence this trial supports is not 'it works' but 'it is better than the steroid by itself'.

But here that design is the more useful one. Steroid alone is already in use for keloids. The choice a patient actually faces is whether to add 5-FU.

Second, note that complications were fewer. It is easy to assume that adding a drug adds adverse effects. In this trial it was the other way round. An explanation would be that less steroid is needed, but the abstract does not give that reason. We do not invent one.

Third, recurrence could not be assessed. The paper wrote that in its own limitations. And recurrence is not a secondary question in keloids. Flat at 12 weeks and flat a year later are different stories.

Fourth, the nature of a network meta-analysis. It pooled 24 trials, but indirect comparisons are in there. With a trial of A against B and another of B against C, the ranking of A against C is estimated. That is weaker than a direct head-to-head. Hence the paper's own level of evidence 3, and its call for head-to-head trials with standardised endpoints.

Fifth, it was restricted to English-language publications. Given that keloid prevalence differs with skin colour, that restriction is not a small one.

Sixth, it is 66 people at a single centre.

So it sits at 'moderate'. This badge is about the combination. What there is on monotherapy is written separately below.

Randomised controlled trial in people · 66 participants · 12 weeks · Compared with another active ingredient · Funding not declared · Endpoint scores from blinded assessors PMID 39355745
Randomised controlled trial in people (24) · sample size not reported · Compared with another active ingredient · Funding not declared · Endpoint scores from blinded assessors PMID 40972598

Not established

Used alone it was not superior — the same analysis says so

One of the results of the same 2026 network meta-analysis. And the reason this entry has to stand separately on this page.

What the analysis wrote is this: bleomycin and 5-fluorouracil monotherapies provided intermediate outcomes without statistical superiority.

How to read it.

First, it is not 'it does not work'. It says the outcomes were intermediate. They just did not reach the point where superiority can be claimed statistically. This site writes those two as different sentences.

Second, that settles where this procedure sits. The combination above ranked first; monotherapy here was not superior. Same drug, different place depending on how it is used. The question this site keeps asking on ingredient pages — what is it with — here changes the conclusion.

Third, hiding this sentence would make the page look tidier. Carry only the result that the combination ranked first, leave this entry out, and 5-FU reads as good on its own. So we write it.

Fourth, read the other lines of the same analysis alongside.

botulinum toxin A — first in response, not significant for recurrence. The same direction as the keloid entry on the botulinum toxin page
verapamil — significantly less effective than the steroid alone

Fifth, the rankings include indirect comparisons. Do not read a network meta-analysis ranking as if it were a head-to-head result. The paper gives itself level of evidence 3.

So monotherapy sits at 'not established'. That does not delete the badge above — the two entries answer different questions.

Randomised controlled trial in people (24) · sample size not reported · Compared with another active ingredient · Funding not declared · Endpoint scores from blinded assessors PMID 40972598

Known risks

It hurts. Scar tissue is dense, so the injection goes in against pressure. The same is written on the intralesional corticosteroid page.
Ulceration, erosion and pigment change at the injection site have been reported. In the 66-patient trial above, complications were fewer in the combination group.
Pigment change is more visible on darker skin — which overlaps with where keloids are more common.
The steroid has its own adverse effects — thinning skin, visible vessels, loss of colour. One reason for using a combination is to need less steroid.
It is a chemotherapy drug. How much, how often, and whether blood monitoring is needed are matters for a clinic. This site does not write doses.
It is not used in pregnancy, by the nature of 5-fluorouracil. Say so if pregnancy is possible.
The scar can come back up. The trial above could not assess recurrence.
The plan differs depending on whether it is a keloid or a hypertrophic scar. That distinction belongs in a clinic.

What is not established

Recurrence is the largest gap. The 66-patient trial wrote itself that recurrence could not be assessed. And in keloids that is not a secondary question.
No placebo-controlled trial is on this page. Every comparator is another treatment.
We do not write concentrations or ratios. What concentration, and in what ratio with the steroid, varies between trials, and this site does not estimate.
The network meta-analysis was restricted to English-language publications. Given that keloid prevalence differs with skin colour, that restriction can affect the result.
Comparisons with surgery, pressure, silicone gel and cryotherapy are not on this page. The analysis above compares intralesional injections with each other.
There is nothing on prevention. We did not verify trials of using it to stop a keloid forming after surgery.
How long, and how many sessions at most, we did not verify in the original papers.
We have not yet opened the primary Korean regulatory classification, so it stays 'being verified'.

Whether to have it done is a decision to make with a doctor.

What this article relies on

PubMed — 미국 국립의학도서관 문헌 데이터베이스National Library of Medicine · Checked on 2026-09-16