Tripeptide-29

Tripeptide-29 is a synthetic signaling peptide used for anti-aging/firming, typically at very low concentrations (often well under 1%) in leave-on products. Peptides are generally non-sensitizing and show low rates of irritation in standard patch testing, with reactions more often attributable to the vehicle or preservatives than the peptide itself. In highly reactive or eczema-prone skin, any leave-on bioactive can rarely sting on compromised barrier, so I rate it very gentle rather than inert for patient safety. Safety Notes: In mass-market leave-on moisturizers and serums, Tripeptide-29 is frequently used at very low levels (around 0.0001–0.005%) as part of multi-peptide complexes or proprietary blends where the INCI listing does not imply high active loading. Higher-strength consumer-available anti-aging serums/ampoules and single-peptide focus formulas have been observed up to ~0.05–0.1% active tripeptide, with practical upper bounds driven by cost and diminishing formulation benefit rather than explicit regulatory limits. Use is overwhelmingly in leave-on products; rinse-off products, when present, tend to sit at the low end due to short contact time.