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Cysteine hydrochloride

CAS 7048-04-6 · 60/100 · High conf.

Also registered as 1 other CAS number

345909-32-2

Cysteine hydrochloride chemical structure

Concern score

60/100High concern based on regulatory listings.
High confidence

Cysteine hydrochloride in plain language

What it is

Also known as Cysteine hydrochloride monohydrate · L-cysteine hydrochloride hydrate · L-cysteine monohydrochloride · L-Cysteine, hydrochloride, monohydrate · Cysteine hcl · (2R)-2-amino-3-sulfanylpropanoic acid;hydrate;hydrochloride

Show all 28 names

L-cysteine monohydrochloride monohydrate · L-Cysteine--hydrogen chloride--water (1/1/1) · (2R)-2-amino-3-sulfanylpropanoic acid hydrate hydrochloride · (R)-2-Amino-3-mercaptopropanoic acid hydrochloride hydrate · (R)-2-Amino-3-mercaptopropanoic acid hydrochloride xhydrate · Cysteine, l-, hydrochloride monohydrate · Cysteine hydrochloride (USP) · Cysteine monohydrate hydrochloride · Cysteine, hydrochloride, hydrate (1:1:1) · Cysteine, hydrochloride, monohydrate, L- · Elcys · Elcys (TN) · H-Cys-OH.HCl.H2O · L-CYSTEINE HCl MONOHYDRATE · L-cysteine hydrochloride monohydrate · L-Cys-OH.HCl.H2O · L-Cysteine HCl hydrate · L-Cysteine monohydrate monochloride · L-Cysteine, hydrochloride, hydrate (1:1:1) · Nouress · UNII-ZT934N0X4W · Cysteine (as hydrochloride)

What it does

We don't have a plain-language description for Cysteine hydrochloride yet.

Is it a concern?
High concern: no hazard classifications on record.

Why it's flagged

EPA CPDat observed this chemical in 5 composition records across product categories including Food and drug, 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. Cysteine hydrochloride appears in these published regulatory listings.

  • In marketed US drugs
  • Inactive ingredient in US drugs

Recorded in these product areas

  • Found in consumer products
  • Pharma
  • Food
  • Industrial
  • USFDAinactive ingredient database9 entries — 2 administration routes
    • Route: INTRAVENOUS; Dosage form: INJECTION, POWDER, LYOPHILIZED, FOR SOLUTION; Maximum daily exposure: 100 mgSource →
    • Route: INTRAVENOUS; Dosage form: INJECTION, SOLUTION; Maximum daily exposure: 100 mgSource →
    • Route: INTRAVENOUS; Dosage form: SOLUTION; Maximum daily exposure: 100 mgSource →
    • Route: ORAL; Dosage form: CAPSULE; Potency: NASource →
    • Route: ORAL; Dosage form: SUSPENSION; Maximum daily exposure: 3 mgSource →
    • Route: ORAL; Dosage form: TABLET, EXTENDED RELEASE; Maximum daily exposure: 24 mgSource →
    • Route: ORAL; Dosage form: TABLET, FILM COATED, EXTENDED RELEASE; Maximum daily exposure: 32 mgSource →
    • Route: INTRAVENOUS; Dosage form: INJECTION, POWDER, FOR SOLUTION; Potency: 1 mgSource →
    • Route: INTRAVENOUS; Dosage form: INJECTION; Potency: 1.5 %w/vSource →
  • EUEFSAEFSA opinion2 entries
    • Scientific Opinion on the safety and efficacy of the use of amino acids (chemical group 34) when used as flavourings for all animal species (EFSA FEEDAP)Source →
    • Scientific Opinion on the safety and efficacy of L-cysteine hydrochloride monohydrate as a flavouring additive for pets (EFSA FEEDAP)Source →
  • USEPAcommercial use observedEPA CPDat observed this chemical in 5 composition records across product categories including Food and drug, Laboratory supplies.
    • EPA CPDat observed this chemical in 5 composition records across product categories including Food and drug, Laboratory supplies.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.

  • JECFA

    Joint FAO/WHO Expert Committee on Food Additives

    No JECFA evaluation on file.

  • EFSA

    European Food Safety Authority

    • Scientific Opinion on the safety and efficacy of the use of amino acids (chemical group 34) when used as flavourings for all animal species (EFSA FEEDAP)

      2014 · EU EFSA listing · Read the source →

    • Scientific Opinion on the safety and efficacy of L-cysteine hydrochloride monohydrate as a flavouring additive for pets (EFSA FEEDAP)

      2013 · EU EFSA listing · Read the source →

Evidence & sources

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

8 data sources

Where this comes from

  • EFSA OpenFoodTox

    regulatory · updated 2026-10-04

    Open →

  • EPA Chemical and Products Database

    exposure · updated 2019-02-27

    Open →

  • EPA DSSTox Identifiers

    chemistry · updated 2025-12-29

    Open →

  • FDA Inactive Ingredient Database

    regulatory · updated 2026-01-09

    Open →

  • FDA National Drug Code Directory

    regulatory · updated 2027-12-31

    Open →

  • FDA GSRS UNII

    registry · updated 2026-02-26

    Open →

  • openFDA Substance

    registry · updated 2026-05-24

    Open →

  • PubChem Live Enrichment

    chemistry · updated 2026-05-17

    Open →
Reference links (3)
Openfda substance

accessdata.fda.gov

Read →
Openfda substance

dailymed.nlm.nih.gov

Read →
Openfda substance

drugoffice.gov.hk

Read →

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 FDA National Drug Code directory has listed Cysteine hydrochloride in a product composition. These are source records, not Greenveil catalog products.

Source records

6

See products using Cysteine hydrochloride →

Catalog

Found in these products

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

See all 41 →Find products without it →