Lysine HCI



Lysine HCI at a glance

  • Amino acid salt
  • May be animal-derived or made in a lab
  • Plays a role in helping keep skin hydrated
  • Produces supportive substances that keep skin looking youthful and smooth

Lysine HCI description

Lysine HCI is an amino acid salt that may be animal-derived or made in a lab (Paula’s Choice uses the synthetic form). Like all amino acids and their derivatives, lysine HCI plays a role in keeping skin hydrated by aiding the balanced transport of water through skin’s layers. Lysine also plays a role in helping skin produce supportive substances that keep it looking smooth and youthful.

Lysine HCI references

  • Amino Acids in Nutrition and Health, August 2020, pages 187-199
  • Current Medicinal Chemistry, 2018, pages 5,512-5,527
  • PLoS ONE, February 2018, ePublication
  • International Journal of Cosmetic Science, August 2009, ePublication
  • Essays in Biochemistry, November 2012, pages 113-133
  • Amino Acids, June 2012, pages 2,481-2,489

Peer-reviewed, substantiated scientific research is used to assess ingredients in this dictionary. Regulations regarding constraints, permitted concentration levels and availability vary by country and region.

Ingredient ratings


Proven and supported by independent studies. Outstanding active ingredient for most skin types or concerns.


Necessary to improve a formula's texture, stability, or penetration.


Generally non-irritating but may have aesthetic, stability, or other issues that limit its usefulness.


There is a likelihood of irritation. Risk increases when combined with other problematic ingredients.


May cause irritation, inflammation, dryness, etc. May offer benefit in some capability but overall, proven to do more harm than good.


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Not rated

We have not yet rated this ingredient because we have not had a chance to review the research on it.