Supplement Label Allergens: How to Read Them in the US

Under US law, a dietary supplement label must declare any of nine major food allergens: milk, eggs, fish, crustacean shellfish, tree nuts, peanuts, wheat, soybeans and sesame. The declaration has to use the plain name of the food source, and it can appear in the ingredient list, in parentheses, or in a “Contains” line next to it. What the law does not require is a promise that the product was made on an allergen-free line. That gap is where most of the confusion starts, and this guide covers how to read both sides of it.

TL;DR

• Nine major allergens must be declared on supplements sold in the US. Sesame became the ninth on January 1, 2023.
• Check two places: the Supplement Facts panel and the “Other Ingredients” list. Capsule shells, binders, flavors and lecithin are common hiding spots.
• “May contain” and “processed in a facility with” statements are voluntary. Their absence does not prove a product is free of cross-contact.
• Cross-check a label in the NIH Dietary Supplement Label Database, and email the brand with specific questions before you buy.
• Third-party testing and published Certificates of Analysis (COAs) support quality, but they do not replace the allergen declaration.

Table of Contents

• The nine major allergens on US supplement labels
• Where the allergen declaration should appear
• Where allergens hide in supplements
• What “may contain” and “made in a facility” statements mean
• A worked example: reading a label step by step
• Check beyond the bottle
• A practical routine before you buy
• Our perspective at Mycelia Link
• Shop labels you can check
• FAQ
• Sources

The nine major allergens on US supplement labels

The FDA lists nine major food allergens: milk, eggs, fish, crustacean shellfish, tree nuts, peanuts, wheat, soybeans and sesame. Sesame was added by the FASTER Act and has been required on packaged foods and dietary supplements since January 1, 2023. The FDA also notes that products already in the supply chain before that date did not have to be pulled, so some older stock may not list sesame.

FDA’s question-and-answer guidance confirms that the labeling rules apply to all packaged foods, including dietary supplements, that are made in or imported into the US. Supplements are not a separate, looser category when it comes to these nine.

Two details trip people up:

• Fish, shellfish and tree nuts are named by type. A label has to say which tree nut (almond, walnut, pecan) or which species of fish or crustacean shellfish is present, not just “nuts” or “seafood.”
• Only these nine are covered by the mandatory declaration. Other ingredients people react to, such as corn, mustard or certain fruits, are not on the federal list. If you react to something outside the nine, the ingredient list is your only source, and a call or email to the brand becomes more important.

Where the allergen declaration should appear

The FDA guidance allows a few formats. The major allergen has to be declared by the name of its food source, and you will see it done in one of these ways:

1. In parentheses within the ingredient list. For example, “whey (milk)” or “lecithin (soy).” Use this when the ingredient name itself does not make the source obvious.
2. In the Other Ingredients list, with the source named. The same logic applies when the allergen is in a non-active ingredient such as a filler or flavor.
3. In a “Contains” statement placed immediately after or next to the Supplement Facts panel or ingredient list. For example, “Contains: milk, soy.”

If a supplement uses a “Contains” line, it should match the ingredient list. When you see a mismatch, treat it as a red flag and contact the brand before you use the product.

Read the whole label, not just the front

Front-of-pack claims like “Dairy-Free” or “Nut-Free” are marketing copy until you check them against the ingredient list. Flip the bottle over and read:

• The Supplement Facts panel, including the source of each active ingredient (for example, “from fish oil” or “from soy”).
• The Other Ingredients list.
• Any “Contains” line.
• Any voluntary advisory line about shared equipment.

We lay out a fast routine for this in our two-minute checklist to read supplement labels and verify COAs.

Where allergens hide in supplements

The FDA guidance and its commentary on formulation flag a theme: hidden allergens often sit in excipients and flavors, not in the headline ingredient. The following are worth a second look.

This is a list of places to check, not a statement that these ingredients always contain an allergen. Many are made from non-allergenic sources, and the label should tell you which. We go deeper on this category in our guide to inactive ingredient supplement risks, and on artificial additives to check in common supplements.

Why a label can be wrong

The usual cause of an undeclared allergen is not a villain. It is a supply chain change. A manufacturer swaps a raw material supplier or tweaks a formula and the printed label lags behind. The FDA’s recall archive shows how this plays out in practice: for example, one allergy alert for a powder with potential undeclared milk is a typical entry. Recalls like this are why the cautious habit is to re-read the label every time you buy a new lot, not just the first time.

What “may contain” and “made in a facility” statements mean

These lines are called advisory statements. They are not part of the mandatory declaration. As industry guidance summarizes, statements such as “may contain traces of tree nuts” are voluntary, and the FDA does not dictate their exact wording.

Federal food-safety guidance also makes the intent clear: they exist for situations where good manufacturing practices and sanitation procedures cannot fully remove the risk of cross-contact, and they are not a substitute for proper cleaning. That document is written for meat and poultry establishments, so treat it as a description of the general principle rather than a rule specific to supplements.

What this means when you shop:

• A “may contain” line is information. Take it seriously. If you have a severe allergy, it signals that the manufacturer could not rule out cross-contact.
• No advisory line is not a guarantee. A label that says nothing about shared equipment has not told you the line is allergen-free. Unless a brand states it specifically, you do not know.
• Wording varies. “May contain,” “processed in a facility that also handles,” and “made on shared equipment with” can mean different things. When in doubt, ask.

Cross-contact in plain terms

Cross-contact happens when an allergen transfers to a product through shared equipment, utensils or the production environment. The allergen is not an ingredient, but it can still end up in the finished product if cleaning or process flow falls short. That is why the ingredient list alone cannot answer every question for someone with a serious allergy.

A worked example: reading a label step by step

Here is an invented label, used only to show the method. It does not describe any real product.

Serving size: 2 capsules. Active: Mushroom extract blend, 500 mg. Other Ingredients: Vegetable cellulose (capsule), rice flour, sunflower lecithin. Contains: none declared.

Walk through it:

1. Scan the actives. Is the source of each active named? A “blend” with no breakdown gives you less to work with. This is one reason we avoid proprietary blends.
2. Read Other Ingredients one by one. Cellulose capsule, rice flour and sunflower lecithin are not major allergens in themselves. If it had said “lecithin” alone, you would have to find out whether it was soy.
3. Check for a Contains line. Here none is declared, which is consistent with the ingredient list.
4. Look for an advisory line. There is none. That is not proof of an allergen-free facility. If you have a serious allergy, email the brand and ask about shared equipment.
5. Note the lot. Keep the lot number so you can match it to a COA or to a recall notice later.

Check beyond the bottle

Marketing language is not a verification tool. Three better ones:

• The NIH Dietary Supplement Label Database (DSLD). It stores label information from products, including ingredient lists and statements. Here is an example label record showing how a product’s serving size, ingredients and other ingredients are laid out. It is useful for comparing a bottle in your hand with the label the brand filed, and for seeing whether a brand discloses shared-equipment status at all.
• The brand’s COA. A Certificate of Analysis shows what an independent lab tested and found for a specific lot. Read what the lab actually tested for. Many COAs cover identity, potency and contaminants such as heavy metals or microbes, and they do not always include allergen testing. A COA supports quality, but it is not a substitute for the allergen declaration on the label. Our overview of third party supplement testing benefits and what label accuracy testing really means explains the difference.
• A direct question. Email or call and ask: Which allergens are in the product? Is it made on shared equipment? Has the formulation or any supplier changed recently? A brand that answers specifically is telling you something. A vague answer tells you something too.

For a broader look at what good disclosure looks like, see our supplement transparency best practices and the transparent supplement sourcing checklist.

A practical routine before you buy

1. Write down the allergens you need to avoid, including less obvious names of the same source (for example, casein and whey for milk).
2. Read the full label: Supplement Facts, Other Ingredients, Contains line, and any advisory statement.
3. Search the product in the DSLD to compare the label on file with the label in hand.
4. Open the COA for your specific lot and note what was and was not tested.
5. Email the brand with the exact questions that remain.
6. Re-check every new bottle. Formulas and suppliers change.
7. If you have a diagnosed allergy, ask your allergist or doctor before adding any new supplement, and follow the product label.

Our perspective at Mycelia Link

We started Mycelia Link because supplement labels often tell you less than they should. Our approach is simple: third-party testing, published COAs, clear labels, and no proprietary blends. When a label lists what is in the bottle, you can check it against what a lab found.

We also try to be straight about limits. A COA tells you what was tested, not everything that could matter to you. A label with no “may contain” line does not settle the question of shared equipment. If you are managing an allergy, read the label of each product line you consider, and if the label does not answer your question, write to us. We would rather answer a detailed allergen question than have you guess.

We explain what the lab results show instead of making health promises, and we hold ourselves to the same standard in how we talk about allergens: say what the label says, say what it does not say, and let you decide.

— Mycelia Link Industries

Shop labels you can check

If you want to compare labels and COAs for yourself, browse our supplements and functional mushroom supplements. Every product is third-party tested and the Certificates of Analysis are published. If you have an allergen question about a specific product, contact us at info@mycelialink.com or text or call (580) 823-0004. Customers are also covered by our Customer Satisfaction Guarantee: if you’re not satisfied, contact us and we’ll make it right.

FAQ

What are the nine major allergens on supplement labels?

They are milk, eggs, fish, crustacean shellfish, tree nuts, peanuts, wheat, soybeans and sesame. Sesame was added effective January 1, 2023. The FDA treats these as the major food allergens for packaged foods and dietary supplements.

Does “may contain” mean a supplement is unsafe for me?

Not automatically, but you should treat it as a warning if you have a serious allergy. These statements are voluntary and signal that cross-contact could not be ruled out. If you have a diagnosed allergy, talk to your allergist or doctor, and ask the brand what the statement refers to.

If a label does not list my allergen, is the product allergen-free?

Not necessarily. The label tells you which major allergens are ingredients. Unless a brand states it specifically, you cannot assume the product was made on an allergen-free line. Contact the brand and ask about shared equipment and recent formulation changes.

Does a COA show allergens?

Only if the lab tested for them. A COA reports what was tested on a specific lot, and many cover identity, potency and contaminants rather than allergens. Read the test list, and ask the brand if allergen testing is not shown.

Sources

• FDA: The FASTER Act, Sesame Is the Ninth Major Food Allergen
• FDA: Guidance for Industry, Questions and Answers Regarding Food Allergens (Edition 5)
• FDA: Allergy alert on potential undeclared milk in a powder product
• NIH Office of Dietary Supplements: Dietary Supplement Label Database example label
• Esko: Food Allergen Labeling Requirements in 2026

Recommended

• Two Minute U.S. Checklist to Read Supplement Labels and Verify COAs
• Supplement Label Accuracy Testing: What It Really Means
• Inactive Ingredient Supplement Risks: What You Need to Know
• Identify Artificial Additives in Common Supplements: What to Check

This article is for informational and educational purposes only and is not medical advice. Research peptides sold by Mycelia Link are for laboratory research use only and are not for human or animal consumption. Statements about dietary supplements have not been evaluated by the Food and Drug Administration; these products are not intended to diagnose, treat, cure or prevent any disease.