Kirkland Signature
Part of Costco
Kirkland Signature has a SupplementChecker.co trust score of 80/100, which is a Grade A, indicating a low risk level. Kirkland Signature products are USP Verified, meaning they've undergone identity, strength, and purity testing. While the brand has some positive attributes, consumers should be aware of elevated FDA adverse event reports.
Kirkland Signature Trust Summary
- Trust Score
- 80/100 (Very Good)
- Grade
- A
- Risk Level
- LOW
- Third-Party Tested
- Yes (USP)
- FDA Recalls
- 0
- Adverse Events
- 26
- Years in Business
- 31 years
- GMP Certified
- Yes
Kirkland Signature has a trust score of 80/100 (Very Good). The brand is third-party tested by USP, has no FDA recalls on record and 26 adverse event reports and has been in business for 31 years.
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Red Flags
- ⚠Elevated FDA adverse event reports (26)
Verified Strengths
- ✓USP Verified — identity, strength, and purity tested
- ✓Established brand — operating since 1995 (31 years)
Certifications
Third-party testing means an independent laboratory has verified this product's contents, purity, and potency match what's on the label.
FDA Record
Is Kirkland Signature Third-Party Tested?
Yes — Kirkland Signature is USP-verified. This means an independent laboratory has verified that the products' contents, purity, and potency match their label claims. They also maintain GMP (Good Manufacturing Practice) certification.
Is Kirkland Signature a Good Brand?
Kirkland Signature scores 80/100 (A) — this is an above-average score indicating a trustworthy brand. Kirkland Signature has a clean FDA record with no warnings or recalls. The brand holds third-party certifications (USP-verified), which is a strong quality indicator.
About Kirkland Signature
Kirkland Signature is a brand of supplements and other products owned and sold by Costco. Founded in 1995, Kirkland Signature has been in business for 31 years. The brand is known for offering a wide range of products at competitive prices, primarily available to Costco members.
Product Specialization
Kirkland Signature specializes in vitamins, minerals, and supplements. Popular products include multivitamins, fish oil, glucosamine, and various single-ingredient vitamins like Vitamin D and Vitamin C. These products are widely available in Costco stores and online.
Testing & Certifications Explained
Kirkland Signature's USP Verification mark indicates that their products have been tested by the United States Pharmacopeia (USP), an independent organization. This verification ensures that the supplement contains the ingredients listed on the label, in the declared potency and amount, and that it does not contain harmful levels of contaminants. This provides an added layer of assurance regarding product quality and safety.
How Kirkland Signature Compares
Compared to brands like Nature Made (trust score 85/100, USP Verified) and NOW Foods (trust score 90/100, Informed Sport Certified), Kirkland Signature's trust score is competitive. However, some competitors offer greater transparency through published lab results. Other brands like Garden of Life (trust score 75/100, NSF Certified) have different certification focuses.
Buying Guidance
Given Kirkland Signature's trust score and USP Verification, their products represent a reasonable option for consumers seeking affordable supplements. Consumers should consider the elevated FDA adverse event reports and, if concerned, consult with a healthcare professional before use. Purchase Kirkland Signature products directly from Costco or Costco.com to ensure authenticity and check the product's expiration date upon arrival.
Frequently Asked Questions
Has Kirkland Signature had any recalls?
Are Kirkland Signature supplements third-party tested?
Is Kirkland Signature safe?
Is Kirkland Signature a good brand?
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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 regulatory 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, Health Canada (LNHPD / recalls-rappels), NSF.org, USP.org, and publicly available brand information. Last updated: 4/9/2026.
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- Trust Score
- 80/100
- Grade
- A
- Risk Level
- LOW
- Third-Party Tested
- Yes
- FDA Recalls
- 0
- Adverse Reports
- 26
- Founded
- 1995