What does Cuprous oxide do?

Used in cosmetics as a skin-conditioning agent. Cuprous Oxide is the inorganic oxide.

Is Cuprous oxide safe?

Moderate concern: no hazard classifications on record. It is listed for cosmetic use in the EU.

beauty
food
industrial
pharma

Cuprous oxide

CAS 633343-78-9 · 40/100 · High conf.

Also registered as 1 other CAS number

1317-39-1

Concern score

40/100Moderate concern based on regulatory listings.

High confidence

Cuprous oxide in plain language

What it is: Also known as Copper (i) oxide · C.I. 77402 · Copper oxide (cu(sub 2)O) · Copper(i) oxide · Dicopper(1+) oxide · Red copper oxide
Show all 54 names
Ag copp 75 · Caocobre sandoz · Copper red CU2O · COPPER(1+) oxide · Copper(i) oxide (CU2O) · Copperoxy · Cupramar · Cupron a · Chem Copp 50 · Cobre Sandoz · Copper (1) oxide · Copper Sandoz · Copper oxide (Cu2O) · Copper protoxide · Copper suboxide · Dicopper monooxide · Dicopper monoxide · Dicopper oxide · Fco-m 6 · Frc 05B · Frc 10A · Frc-af · Frc-n 10 · Fungimar · Gg · Gg (pigment) · Kymera 421001-099 · Lolo tint 97 · Lolo tint lm · Nc 102 · Nc 301 · Nc 301 (oxide) · Nc 303 · Nc 803 · Nordox · Nordox 30WG · Nordox 75WG · Nx 3 · Perenox · Purple copp · R 30 · R 30 (oxide) · Red copp 97N premium · Yellow cuprocide · copper oxide · copper oxide (sara 313) · copper oxide (sara iii) · cuprous oxide cas# 1317-39-1
What it does: Used in cosmetics as a skin-conditioning agent. Cuprous Oxide is the inorganic oxide.
Skin conditioning
Conditioner
Is it a concern?: Moderate concern: no hazard classifications on record. It is listed for cosmetic use in the EU.

Why it's flagged

EPA CPDat observed this chemical in 231 composition records across product categories including Home maintenance, Raw materials, Laboratory supplies.

The score describes this ingredient's chemical identity — its hazard profile from published classifications and regulatory status — not the safety of any product it appears in.

Regulation

No restrictions found. Cuprous oxide appears in these published regulatory listings.

In marketed US drugs

Recorded in these product areas

Found in consumer products
Pharma
Industrial

EUEFSAConclusion on Pesticides Peer Review2 entries
- Conclusion regarding the peer review of the pesticide risk assessment of the active substance Copper (I), copper (II) variants namely copper hydroxide, copper oxychloride, tribasic copper sulfate, copper (I) oxide, Bordeaux mixture (EFSA)Source →
- Conclusion on the peer review of the pesticide risk assessment of confirmatory data submitted for the active substance Copper (I), copper (II) variants namely copper hydroxide, copper oxychloride, tribasic copper sulfate, copper (I) oxide, Bordeaux mixture (EFSA)Source →
EUEFSAEFSA opinion2 entries
- Peer review of the pesticide risk assessment of the active substance copper compounds copper(I), copper(II) variants namely copper hydroxide, copper oxychloride, tribasic copper sulfate, copper(I) oxide, Bordeaux mixture (EFSA)Source →
- Safety and efficacy of dicopper oxide as feed additive for all animal species (EFSA FEEDAP)Source →
EUCosIngActiveCuprous Oxide is the inorganic oxide. See "Regulatory and Ingredient Use Information," for Colorants in Volume 1, Introduction, Part A.
- Cuprous Oxide is the inorganic oxide. See "Regulatory and Ingredient Use Information," for Colorants in Volume 1, Introduction, Part A.Source →
USEPAcommercial use observedEPA CPDat observed this chemical in 231 composition records across product categories including Home maintenance, Raw materials, Laboratory supplies. EPA CPDat classifies this chemical for functional uses including Softener and conditioner.
- EPA CPDat observed this chemical in 231 composition records across product categories including Home maintenance, Raw materials, Laboratory supplies. EPA CPDat classifies this chemical for functional uses including Softener and conditioner.Source →
USFDAmarketed drug occurrenceFDA NDC lists this ingredient in 6 active drug products and 6 total products.
- FDA NDC lists this ingredient in 6 active drug products and 6 total products.Source →
USFDAlisted in openFDA substanceopenFDA substance registry classifies this ingredient as chemical.
- openFDA substance registry classifies this ingredient as chemical.Source →

Expert safety opinions

Independent scientific assessments cited by the records we hold, with the year and link where the record gives one.

SCCS
EU Scientific Committee on Consumer Safety
No SCCS opinion on file.
CIR
Cosmetic Ingredient Review (US expert panel)
No CIR safety assessment on file.
EFSA
European Food Safety Authority
- Conclusion regarding the peer review of the pesticide risk assessment of the active substance Copper (I), copper (II) variants namely copper hydroxide, copper oxychloride, tribasic copper sulfate, copper (I) oxide, Bordeaux mixture (EFSA)
  2008 · EU EFSA listing · Read the source →
- Peer review of the pesticide risk assessment of the active substance copper compounds copper(I), copper(II) variants namely copper hydroxide, copper oxychloride, tribasic copper sulfate, copper(I) oxide, Bordeaux mixture (EFSA)
  2018 · EU EFSA listing · Read the source →
- Safety and efficacy of dicopper oxide as feed additive for all animal species (EFSA FEEDAP)
  2016 · EU EFSA listing · Read the source →
- Conclusion on the peer review of the pesticide risk assessment of confirmatory data submitted for the active substance Copper (I), copper (II) variants namely copper hydroxide, copper oxychloride, tribasic copper sulfate, copper (I) oxide, Bordeaux mixture (EFSA)
  2013 · EU EFSA listing · Read the source →

Evidence & sources

No graded research studies for Cuprous oxide yet. This record is compiled from the published data sources below — registries and regulatory listings, not study findings.

7 data sources

Where this comes from

CosIng
regulatory · updated 2026-09-23
Open →
EFSA OpenFoodTox
regulatory · updated 2026-10-04
Open →
EPA Chemical and Products Database
exposure · updated July 2006
Open →
EPA DSSTox Identifiers
chemistry · updated 2025-12-29
Open →
FDA National Drug Code Directory
regulatory · updated 2026-12-31
Open →
FDA GSRS UNII
registry · updated 2026-02-26
Open →
openFDA Substance
registry · updated 2026-05-24
Open →

Suitability

Context-specific fit derived from published classifications and the current ingredient evidence profile.

Food use

Food-use source coverage is present in the current record.

Good fit

The ingredient appears in food-oriented source coverage or allowed-use references, which makes food use easier to support than a context with no domain signal at all.

Fragrance avoidance

No fragrance-linked caution surfaced in the current profile.

Good fit

This ingredient does not currently read as a fragrance-linked driver in the published evidence and hazard profile.

Where it has been recorded

How often EPA CPDat has listed Cuprous oxide in a product composition. These are source records, not Greenveil catalog products.

Source records

231

Named organisations

Home maintenanceRaw materialsLaboratory suppliesLandscape/yardVehicleRoad vehicles

Typical roles

Skin conditioningConditioner

See products using Cuprous oxide →

Catalog

Found in these products

Their ingredient lists include Cuprous oxide; each product's own rating depends on its whole formula, so it is shown on the product page, not here.

See all 12 →Find products without it →