California will begin requiring age verification for certain dietary supplements, including creatine products marketed for muscle building, starting January 1, 2027, under a law signed by Gov. Gavin Newsom.

Assembly Bill 2030, authored by Democratic Assemblymember Josh Lowenthal, prohibits retailers and delivery services from selling or providing over-the-counter supplements marketed for muscle building or weight loss to anyone under 18 without a prescription. The law specifically identifies creatine among ingredients that can trigger the restrictions when products are marketed for those purposes.

Under the new requirements, in-person retailers must request identification when they cannot reasonably determine that a customer is at least 18 years old. Online sellers must verify a buyer's name, date of birth, and address through a third-party database or require delivery with an adult signature and photo identification.

The restrictions do not automatically apply to every product containing creatine or protein. Coverage depends on how a supplement is labeled, marketed or represented, meaning some products commonly sold in gyms, nutrition stores and online retailers could fall under the law depending on their advertising and claims.

Supporters of the legislation have cited concerns about supplement use among teenagers and its potential connection to eating disorders, body image issues and depression. However, industry groups have raised concerns that the law's broad marketing language could extend to products commonly used by adults, creating additional compliance requirements for retailers and manufacturers.

The legislation will require businesses selling covered products to update their age-verification procedures before the January 2027 implementation date.