Prop 65 Warning Requirements for Supplement Brands Selling in California

California’s Proposition 65 requires a warning on products that expose consumers to listed chemicals above a threshold — and supplements are frequently caught by it, because heavy metals and some botanical constituents appear on the list. The warning is not a defect in your product, but failing to give it is a violation that attracts penalties. Here is what it means in practice.

On this page: What Prop 65 Requires · Applying It to Your Product · Practical Consequences

What Prop 65 Requires

1. What is Proposition 65?
   A California law requiring a clear and reasonable warning before exposing consumers to chemicals on the state’s published list, which includes a large number of substances — some naturally occurring in foods and botanicals.
2. Why does it affect supplements?
   Because supplements are concentrated. A botanical extract can concentrate a naturally occurring listed substance to a level that exceeds the safe-harbour threshold, even though the same substance in ordinary food would not trigger a warning.
3. How is the threshold set?
   Each listed chemical has a safe-harbour level, usually based on a daily exposure figure. Below it, no warning is required; above it, the warning is. The levels are specific to each chemical and are revised when they change.
4. Is the warning a sign my product is unsafe?
   Not necessarily. It means an exposure exceeds a regulatory threshold, which is a legal trigger rather than a statement of harm. Many ordinary foods carry the warning for naturally occurring substances.

Applying It to Your Product

1. Who decides whether a warning is needed?
   It is the seller’s responsibility, based on the product’s composition and the exposure it creates. The manufacturer supplies the analytical data; the brand decides and applies the label.
2. What testing supports the decision?
   Heavy-metal testing is the most common requirement, plus testing for any listed substance associated with your specific ingredients. The results are compared against the current safe-harbour levels.
3. What does the warning look like?
   A prescribed short-form or long-form warning with the specified wording, placed so it is seen before purchase where possible. The wording and the symbol are specified, and a paraphrase is not equivalent.
4. Can I test out of it?
   Sometimes. If testing shows exposure below the safe-harbour level, no warning is required. Where the level is close to the threshold, batch-to-batch variation matters, so a single low result is not a permanent exemption.

Practical Consequences

1. What is the risk of not warning?
   Private enforcement actions and statutory penalties, which in California have been substantial. The exposure is legal and financial rather than a product-quality issue.
2. Does it affect online sales to California?
   Yes. A product shipped into California is covered, so an online seller cannot avoid it by being based elsewhere. Marketplace listings should also carry the warning where required.
3. How should I handle it with my factory?
   Ask for heavy-metal testing as standard, and ask whether the results are compared against Prop 65 levels rather than only against generic limits. The two are not the same comparison.
4. Does a warning hurt sales?
   It can concern some consumers, but the alternative — a penalty and a removal — is worse. Frame it as a legal notice, because that is what it is, and keep it in the prescribed format.

Related Reading

See label compliance for Amazon listings for the marketplace side, and quality and testing for the tests we run as standard.

These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure or prevent any disease.