Kirkland Signature

Part of Costco

https://www.costco.com Est. 1995 (31 years)

**** Kirkland Signature is Costco's private label supplement brand, established in 1995, specializing in vitamins, minerals, fish oil, multivitamins, and glucosamine products. The brand holds USP Verified and GMP certifications, demonstrating commitment to quality standards, with no FDA warning letters or recalls in its 31-year history. However, the brand has accumulated 39 FDA adverse event reports and does not publicly publish independent lab testing results. **

Red Flags

⚠Elevated FDA adverse event reports (39)

Verified Strengths

✓USP Verified — identity, strength, and purity tested
✓Established brand — operating since 1995 (31 years)

Certifications

USP VerifiedGMP CertifiedThird-Party Tested

FDA Record

Warning Letters

Recalls

Adverse Reports

How We Calculated This Score

Every brand starts with a baseline score of 70/100.

Points added for: Third-party certifications (NSF +15, USP +15, Informed Sport +10), publishing lab results (+10), clean FDA record (+10), 10+ years in business (+10), organic certification (+5).

Points deducted for: FDA warning letters (-25), product recalls (-20), high adverse events (-15), no third-party testing (-15), proprietary blends (-10), no GMP (-10).

Score is capped at 0-100. Grade and risk level are derived from the final score.

All data sourced from FDA.gov, NSF.org, USP.org, and publicly available brand information. Last updated: 3/20/2026.