The answer so far

Start with the serving size. Check every active ingredient, the amount per serving, added stimulants and the number of servings you actually take. The label tells you what the manufacturer says is present; it does not by itself prove that a product works, is uncontaminated or is suitable for you. US dietary supplements are not FDA-approved for safety or effectiveness before sale, although manufacturers have quality and labelling responsibilities.12

On this page
  1. Start with the serving
  2. What does percent Daily Value mean?
  3. Composition is not effectiveness
  4. Other ingredients, directions and storage
  5. Labels outside the United States
  6. Quality checks have limits
  7. When the contents differ from the label
  8. Claims and interactions
  9. Sources
Follow this question
How do you read a supplement label? Choose a step to explore this subject in more detail.
  1. 1Start with the serving
  2. 2What does percent Daily Value mean?
  3. 3Composition is not effectiveness
  4. 4Other ingredients, directions and storage

Start with the serving

On a US Supplement Facts panel, check the serving size before the amounts. Imagine a label lists 200 mg per serving of two capsules. One capsule represents 100 mg on that label. This is arithmetic, not advice to change how you use a product. Compare the amounts you would actually take, and read the directions as well as the panel.31

What does percent Daily Value mean?

A US label may give a nutrient’s percentage of Daily Value (%DV). This is a reference used for labelling, not a personal target or maximum safe amount. Some ingredients have no established Daily Value, so they have no percentage. A larger percentage does not prove a greater benefit, and food and other products can add to your total. See vitamin A forms and label percentages.31

Composition is not effectiveness

A label may list a nutrient, plant ingredient or proprietary blend. An ingredient can be present without strong evidence that it produces the advertised result. A proprietary blend can make it harder to see the amount of each ingredient and compare products.1

Other ingredients, directions and storage

Look beyond the main panel for flavourings, sweeteners, capsule materials and relevant allergen information. Read the directions and storage or after-opening instructions. A front-of-pack claim does not prove an ingredient works or that the contents survived unsuitable storage. See storage and handling and supplement interactions.23

Labels outside the United States

“Supplement Facts” and %DV are US terms. EU food-supplement labels follow a different framework. They include a recommended daily portion, a warning not to exceed it and a statement that supplements do not replace a varied diet. Vitamin and mineral reference values and wording can differ between markets. Check your actual label and local authority guidance.43

Quality checks have limits

Good manufacturing practices are intended to support a product’s identity, purity, strength and composition. An independent seal may show it passed a particular quality programme. It does not establish that the product treats a disease or improves performance.12

When the contents differ from the label

A 2023 laboratory study examined 25 selected US melatonin gummy products. Where melatonin was detected, measured amounts ranged from 74% to 347% of the labelled amount. Only three of the 25 were within 10% of the stated quantity. This small sample cannot tell you what is in your product or how common discrepancies are today. Melatonin is a hormone, not a vitamin, and its legal classification differs by country.

Keep medicines and supplements, including gummies, out of children’s reach and sight. A US CDC surveillance estimate identified about 11,000 emergency visits for unsupervised melatonin ingestion by children aged five or under during 2019–2022. Most visits did not result in hospitalisation, and the estimate does not count every ingestion. If a child may have swallowed a product unexpectedly, seek prompt advice from a local poison information service or health professional.

A separate 2025 FDA-affiliated survey tested 110 selected US melatonin supplements marketed toward children. Measured content ranged from 0% to 667% of the stated amount. The range describes those samples, not the proportion of inaccurate products across the market. It does not establish whether a particular bottle is safe or effective. See the melatonin guide.567

Claims and interactions

Words such as “natural,” “clinical” or “research-backed” do not replace a trial that matches the product and claim. Supplements can interact with medicines, and several products can contain the same nutrient. Consider the whole list, not just one ingredient.2

Further reading

Trusted external resources selected to help explain this page. They open in a new tab.

Sources, kept close.

Selected supporting sources; this is not a complete literature review.

  1. Dietary Supplements: What You Need to KnowNIH Office of Dietary Supplements · Official consumer fact sheetAccessed 2026-11-03
  2. Questions and Answers on Dietary SupplementsU.S. Food and Drug Administration · Regulator consumer guidanceAccessed 2026-11-03
  3. Dietary Supplement Labeling Guide: Chapter IV. Nutrition LabelingU.S. Food and Drug Administration · Government supplement labelling guidanceAccess checked 2026-11-04 · Source date: 2005-04 · April 2005 US industry guidance on Supplement Facts; check current regulatory guidance.
  4. Food supplements: EU labelling rulesEuropean Commission / Your Europe · Government supplement labelling guidanceAccess checked 2026-11-04 · EU labelling overview, not evidence of a particular product’s quality or effectiveness.
  5. Quantity of Melatonin and CBD in Melatonin Gummies Sold in the USJAMA · Primary laboratory studyAccess checked 2026-11-04 · Source date: 2023-04-25 · Selected US-labelled melatonin gummies purchased in 2022; not a representative market survey or evidence about a specific current product.
  6. Emergency Department Visits for Unsupervised Pediatric Melatonin Ingestion — United States, 2019–2022U.S. Centers for Disease Control and Prevention · Public-health surveillance reportAccess checked 2026-11-04 · Source date: 2024-03-07 · Weighted national estimate based on emergency department visits among children aged five and under, not all ingestions or a measure of risk per product.
  7. A Survey of Melatonin in Dietary Supplement Products Sold in the United StatesDrug Testing and Analysis / PubMed · Primary laboratory product survey, 2025Access checked 2026-11-04 · 110 US products marketed toward children; content range is not a population prevalence estimate. Abstract reviewed; full paper not reviewed.

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