California Prop 65 for Supplement Brands: What You Need to Know

What Prop 65 Is

The Office of Environmental Health Hazard Assessment (OEHHA) maintains the list of chemicals covered by Prop 65. Check the current list against your ingredients and product. The presence of a listed chemical does not, by itself, answer whether a warning is required.

The law covers certain discharges into drinking water sources and warnings for exposures to listed chemicals, subject to exemptions. This guide focuses on the consumer-product warning question. Businesses with fewer than 10 employees are exempt; a small business may still have obligations under its sales agreements.

Exposure at or below an applicable safe-harbor level needs no warning. An exposure above that level does not automatically establish a violation: an independent risk assessment may support an exemption under the regulations. See OEHHA's business FAQ (checked September 18, 2026) for warning and exemption guidance.

Why Prop 65 Matters Outside California

Company location and consumer location are different questions. Use the checks below if your products reach California consumers.

• E-commerce reaches California. Check where your direct store, distributors, and marketplaces sell the product. Do not treat an out-of-state business address as an exemption.
• Contracts allocate work. Read the applicable retailer and distributor agreements. Confirm who supplies warning content, applies it to products, and maintains online displays.
• Private enforcement exists. The statute permits public-interest enforcement actions when its conditions are met. Keep the evidence supporting your decision; do not wait for a dispute to reconstruct it.
• Selling channels need coordination. If a warning is needed, check each California sales channel. A label change does not automatically update an online listing.

Four Metals to Check in a Lab Report

A heavy metals panel can help assess lead, cadmium, arsenic, and mercury. These four do not exhaust the Prop 65 list. Ask which listed chemicals and chemical forms are relevant to your formula, ingredients, and process.

Testing and Compliance Options

Start with the exposure assessment, then decide whether a warning is required. The options below are not an exhaustive list of legal exemptions. OEHHA does not require a specific test or a blanket every-batch testing schedule under its warning regulations.

For guidance on what testing to expect from your manufacturer, see our supplement testing requirements guide. For understanding test results, see our guide to reading a COA.

Warning Label Requirements

OEHHA's safe-harbor regulations provide warning formats and methods deemed clear and reasonable. These formats are optional: a business using an alternative may need to defend it if challenged. Food warnings, including dietary supplements, have specific content under 27 CCR 25607.2. Use the provisions for the relevant exposure.

What the Full-Length Food Warning Includes

• ✓WARNING, CA WARNING, or CALIFORNIA WARNING in bold uppercase
• ✓Food-specific wording about consuming the product; no warning symbol is required for this format
• ✓The relevant listed chemical names and cancer or reproductive-harm wording for the exposure
• ✓The food warning URL: www.P65Warnings.ca.gov/food
• ✓The applicable food-warning presentation and delivery requirements in 27 CCR 25607.1

Where the Warning Must Appear

Follow the applicable food-warning delivery methods in 27 CCR 25607.1. For internet sales, the safe-harbor rules also require an online warning before purchase is completed. The warning can appear on the product display page, through a clearly marked warning link on that page, or through another prominent display before checkout is completed. Purchasers must not have to search the general website content for it. The online warning does not replace the warning delivered on or with the product. See OEHHA's business FAQ.

Common Prop 65 Mistakes

• Assuming it doesn't apply because you're not in California. Check California exposure and applicable exemptions. Where the company is based does not resolve the warning question.
• Using an outdated warning format. The short-form transition depends on when a product was manufactured and labeled. Under 27 CCR 25603(c), products manufactured and labeled before January 1, 2028, may use the prior short-form content regardless of their sale date. Check the applicable food-warning format rather than assuming every older product must be relabeled by the end of 2027.
• Treating a concentration as daily exposure. A result in mcg/g or ppm cannot be compared directly with a limit in mcg/day. Product amount and use matter. Ingredient inclusion rates also matter when working from raw-material data.
• Treating one panel as a complete assessment. Confirm the chemicals, chemical forms, reporting limits, product matrix, and sample plan. Ask what formula, ingredient-source, or process changes would require reassessment.
• Ignoring e-commerce warning requirements. For internet purchases using the safe harbor, a physical warning alone is insufficient. Section 25602(b) also provides online methods: the warning on the product display page, a clearly marked warning link on that page, or another prominent warning before purchase is completed. Do not hide it in general website content.
• Waiting for a lawsuit to take action. Keep the decision basis, lab reports, approved warnings, and channel records together. If you receive a notice, preserve those records and contact qualified counsel promptly.

Getting Started with Prop 65 Compliance

Our recommended preparation checklist helps you give a laboratory or regulatory specialist the information needed for a useful answer.

• ✓Document California sales channels, business size, sales-agreement terms, formula, serving directions, and any existing warning decision.
• ✓Identify the relevant listed chemicals and chemical forms. Agree on the evidence or tests needed; do not assume a four-metal panel covers everything.
• ✓Check units, reporting limits, sample identity, and daily-use assumptions. Ask the specialist to explain the exposure calculation and its regulatory basis.
• ✓Record the applicable exemption, safe harbor, independent risk assessment, or warning decision. Above a safe harbor is a reason for assessment, not an automatic verdict.
• ✓If a warning is needed, approve the applicable food-warning format and check the product, retailer handoff, and online display before purchase.
• ✓Assign an owner for the records and reassessment triggers, such as a changed formula, ingredient source, serving direction, or applicable regulation.

Worked units example: an Inventory Ready illustration, not a lab result. A hypothetical finished powder result of 0.10 mcg/g multiplied by 5 g/day equals 0.50 mcg/day. This shows the unit conversion, not a compliance verdict. A reporting limit, chemical form, exposure assumption, or applicable exemption can change the assessment.

For a broader view of compliance risks, see our supplement compliance risks guide. For label requirements beyond Prop 65, see our packaging and label compliance guide.