# Sentinel node tracers and blue dye: injection, allergic reaction readiness and aftercare

Source: https://onco.cc/protocols/sentinel-node-tracers-and-blue-dye-safety/  
OnCo record `sentinel-node-tracers-and-blue-dye-safety` (Protocol). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

To find the sentinel lymph node, a radioactive tracer and often a blue dye are injected near the tumour. Severe allergic reactions to the blue dye are rare (about 2 in 1,000 in the largest pooled study) but can come late, so the team asks about allergies beforehand and watches you closely for at least an hour. Your urine may be blue for a day and the skin can stay blue-stained for a while.

## Summary

NICE NG101 tells UK breast teams to perform SLNB 'using the dual technique with isotope and blue dye' (2009 recommendation, unchanged in the current guideline). In a systematic review of 24 prospective studies, adding blue dye to isotope raised the identification rate (OR 2.03) but did not lower the false-negative rate. Isosulfan blue: hypersensitivity in about 2% (label), with life-threatening anaphylaxis possible; risk is higher with asthma, allergies, drug reactions or a previous reaction to triphenylmethane dyes; monitor for at least 60 minutes with trained staff and resuscitation available; do not mix with lidocaine in the same syringe; pulse oximetry reads falsely low (maximal at 30 minutes). A 2025 meta-analysis (8 studies, 19,183 breast patients) found 11.65 adverse events per 1,000 and 1.86 per 1,000 needing vasopressors, with no deaths; intraparenchymal injection had more events than peritumoral. NAP6 (UK, 266 severe perioperative anaphylaxis cases) identified Patent Blue as the culprit in 9 of 199, with delayed onset compared with antibiotics and neuromuscular blockers. Technetium tilmanocept: ask about dextran reactions and have resuscitation ready. Indocyanine green fluorescence was equivalent to isotope and superior to dual isotope and blue dye for identification in a 2020 meta-analysis.

## Fields

- Kind: Protocol
- Last checked: 2026-11-11
- Also known as: sentinel lymph node mapping tracer; blue dye anaphylaxis; isosulfan blue reaction; patent blue anaphylaxis; dual technique sentinel node biopsy; lymphatic mapping dye safety

## Connected records

- protocols: [Lymphoedema after breast cancer: risk reduction, surveillance, early compression and treatment](https://onco.cc/protocols/lymphoedema-risk-reduction-surveillance-and-treatment/), [Surgical site infection prevention: skin preparation, antibiotic timing, warming and wound care](https://onco.cc/protocols/surgical-site-infection-prevention/)
- technologies: [Magnetic tracer for sentinel lymph node biopsy (Magtrace and Sentimag)](https://onco.cc/technologies/magnetic-sentinel-node-tracer/), [Sentinel lymph node biopsy](https://onco.cc/technologies/sentinel-node/)
- drugs: [Isosulfan blue (lymphatic mapping dye)](https://onco.cc/drugs/isosulfan-blue/), [Technetium Tc-99m sulfur colloid](https://onco.cc/drugs/technetium-sulfur-colloid/), [Technetium-99m tilmanocept](https://onco.cc/drugs/tilmanocept-tc99m/)
- terms: [Sentinel node biopsy](https://onco.cc/terms/sentinel-lymph-node-biopsy/)
- ideas: [Sentinel node biopsy for breast cancer with fluorescence or isotope alone, without blue dye](https://onco.cc/ideas/idea-pu-sentinel-node-without-blue-dye/)

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