Etidronic Acid

  • CAS No.- 2809-21-4
  • INCI.- Etidronic Acid

Etidronic acid is used as a chelating agent in cosmetics, building complexes with calcium, arsenic, iron and other metal ions to neutralize them. This allows for management of the use of slightly "hard" water, which could, for example, interfere with the surfactants of the product. Chelators are often used in water softeners. This molecule does not pose any problem for human health. Its disadvantage is that, like EDTA, it is very poorly biodegradable and the complexes it forms with metals are found scattered in nature.

Dosage level

Recommended concentration
• max 1.5 % in skin and hair care products (in Etidronic acid)
• max 0.2 % in soap (in Etidronic acid)

Solubility - solubility in water


AppearanceColorless to pale yellow transparent liquid
Active content (% HEDP)58 – 62

Etidronic acid is used for the chelation of metal ions, in particular transition metals (Fe, Cu, Mn, Zn) and water hardness ions (Ca, Mg).
Stability constants of etidronic chelates have been measured and the approximate amount of free ions have been calculated
In most cases, stability constants greater than 5 to 6 are not needed for practical removal of unwanted metal ions.

• Easy to handle • Good efficacy against ion metals • Good stability



  • Skin Care
  • Toiletries
  • Hair Care
  • Sun Care
  • Makeup
  • Baby Care



Natural extracts