# Toxicity grade

Source: https://onco.cc/terms/toxicity-grade/  
OnCo record `toxicity-grade` (Term). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

A 1 to 5 severity scale for side effects: grade 1 mild, grade 2 moderate, grade 3 severe and needing intervention, grade 4 life-threatening, grade 5 fatal. Trials report the percentage of patients with grade 3 or worse.

## Summary

The Common Terminology Criteria for Adverse Events (CTCAE) define each grade for hundreds of specific effects, from nausea to neutropenia; 'grade 3 or higher' is the usual summary of how hard a treatment is to take, and the rates of dose reduction and discontinuation show how often it cannot be given as planned. Grading is done by clinicians and tends to underestimate symptoms that patients feel but doctors do not see (fatigue, nausea), so patient-reported versions (PRO-CTCAE) are increasingly collected. The same word 'grade' in 'tumour grade' means something entirely different.

## Fields

- Kind: Term
- Last checked: 2026-09-09
- Also known as: toxicity; toxicities; toxic; grade 3; grade 4; grade 5; grade 3-4; grade 3/4; grade 3 or higher; grade ≥3; grade 3+; high-grade toxicity; severe toxicity; CTCAE; treatment-related; treatment-related adverse events; TRAEs; TRAE; serious adverse event; serious adverse events; SAE; discontinuation; discontinuation rate; treatment discontinuation; tolerability; tolerable; well tolerated; well-tolerated; safety profile; manageable

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/Common_Terminology_Criteria_for_Adverse_Events
- Wikipedia: https://en.wikipedia.org/wiki/Common_Terminology_Criteria_for_Adverse_Events

## Connected records

- terms: [Bone marrow](https://onco.cc/terms/bone-marrow/), [Chemotherapy](https://onco.cc/terms/chemotherapy-term/), [Cytokine release syndrome (CRS)](https://onco.cc/terms/crs/), [Dose](https://onco.cc/terms/dose/), [Grade](https://onco.cc/terms/tumour-grade/), [Immune-related adverse events (irAEs)](https://onco.cc/terms/irae/), [Interstitial lung disease (ILD) / pneumonitis](https://onco.cc/terms/ild/), [Quality of life](https://onco.cc/terms/quality-of-life/), [Radiotherapy](https://onco.cc/terms/radiotherapy/), [Side effect versus adverse event](https://onco.cc/terms/side-effect-vs-adverse-event/)

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