The safety and efficacy of 2% vitamin C solution spray for relief of mucosal irritation caused by Lugol chromoendoscopy: a multicenter, randomized, double-blind, parallel trial

Lugol chromoendoscopy facilitates endoscopic visualization of esophageal dysplasia and carcinoma. Vitamin C solution (VCS) can theoretically neutralize free iodine, which causes mucosal irritation. The aim was to assess the safety and efficacy of VCS for relieving adverse symptoms caused by Lugol iodine staining.Two hundred forty eligible patients were randomized to receive 20 mL of normal saline solution (NS), 5% sodium thiosulfate solution (STS), or 2% VCS after spraying 10 mL of 2% Lugol iodine solution on the mid-distal esophagus. The primary endpoints were statistically significant reductions in acute and late adverse symptom severity scores. The secondary endpoint was the discoloration effect on esophageal brown iodine-stained mucosa.Spraying both VCS and STS similarly decreased the severity scores of acute (NS vs VCS = 2.58 vs 1.61, P = .040; VCS vs STS = 1.61 vs 1.89, P > .999) and late (NS vs VCS = 1.70 vs 0.91, P = .002; VCS vs STS = 0.91 vs 1.38; P = .212) adverse symptoms after Lugol chromoendoscopy compared with spraying NS. Compared with STS spray, VCS spray alleviated acute acid regurgitation or heartburn (33% vs 15%, P = .017) and late retrosternal discomfort or pain (21% vs 9%, P = .027). Moreover, compared with spraying NS, spraying VCS quickly discolored the iodine-stained mucosa, with a better decolorization score (2.26 vs 3.56, P = .000), and the effects of fading iodine dye were similar between VCS and STS (3.56 vs 3.59, P = .908).VCS can reduce mucosal irritation symptoms induced by Lugol chromoendoscopy and can be routinely recommended. (Chinese Clinical Trial Registry number: ChiCTR1900022000.).