What stops an ingrown toenail returning? Surgery, and phenol makes it stick

An ingrown toenail — where the edge of the nail digs into the skin fold beside it and creates a painful, often infected spot — is common, and there has never been a consensus on the single best way to treat it [s1]. But a Cochrane review of 24 randomised trials, together enrolling 2826 participants, lands on one firm conclusion: when the goal is stopping the nail from growing back into the skin, surgery outperforms the non-surgical options, and a chemical called phenol makes the surgical fix more durable still [s1].

Surgery versus conservative care

The review split its trials into five studies of non-surgical interventions and 19 of surgical ones [s1]. Non-surgical approaches include measures such as fitting a brace on the toe to reshape the nail (orthonyxia) or placing a gutter under the nail edge to lift it off the inflamed skin [s1]. Against these, surgical interventions were better at preventing recurrence than the gutter approach, and probably better than brace treatment [s1]. The headline finding the reviewers drew from the whole body of evidence was blunt: "Surgical interventions are more effective than non-surgical interventions in preventing the recurrence of an ingrowing toenail" [s1].

What phenol adds

The more useful detail is about how the surgery is done. Several trials compared an operation that included chemical ablation of the nail-growing tissue — most often with phenol — against the same kind of operation without it. In 4 of the 12 studies making that comparison, adding chemical ablation significantly reduced recurrence, though in most of those the two surgical procedures were not otherwise identical, so the phenol was not cleanly isolated as the cause [s1].

One trial did isolate it. In a study of 117 participants, partial nail avulsion with matrix excision plus phenol was compared with the identical operation without phenol, and phenol was significantly more effective at preventing recurrence: 14% of toes recurred with phenol versus 41% without (risk ratio 0.34, 95% confidence interval 0.17 to 0.69) [s1]. Because this was the only comparison in which both surgical arms were the same, the reviewers were careful to say that more studies are needed to confirm it — but it is the clearest single result in the review [s1].

What does not seem to matter

The review also looked at what is done after surgery, and here the news is deflating for a lot of common practice. None of the postoperative treatments studied — antibiotics, manuka honey, povidone-iodine with paraffin, hydrogel with paraffin, or paraffin gauze — made any significant difference to infection rates, pain, or healing time [s1]. In other words, the dressing-and-drug rituals that follow the operation did not measurably change how it went; the durable difference came from what was done to the nail matrix during surgery, not from the aftercare [s1].

How firm is the evidence

Firm on direction, softer on precision. The review judged the risk of bias in most trials to be unclear, largely because of incomplete reporting rather than clearly poor methods [s1]. Participants could not be blinded to whether they had surgery or wore a brace, and outcome assessors were reported to be blinded in only 9 of the 24 studies [s1]. None of the trials actually reported the review's intended primary outcomes of symptom relief or regrowth; 16 reported recurrence, which is what most of the conclusions rest on [s1]. So the shape of the answer is trustworthy — surgery beats conservative care, phenol beats plain surgery — while the exact numbers, drawn in the key case from a single 117-person trial, are less settled [s1].

The bottom line

For an ingrown toenail that keeps coming back, the best-supported route to keeping it away is a surgical procedure that treats the nail-growing tissue, ideally with phenol, rather than a brace, a gutter, or elaborate aftercare [s1]. What the review cannot tell a reader is which treatment suits which toe, or when a painful nail needs care at all — a red, swollen, discharging or persistently painful toe, especially in someone with diabetes or poor circulation, is a reason to see a clinician. This article reports what the trials show, not what any individual should do.