Choosing and using dietary supplements safely

  • Investigate before you buy or use. There are many resources in libraries and online. Look past the information that comes from the makers of the products, which can be biased or wrong. Find materials from reliable third parties, such as researchers or government agencies. (See the “To learn more” section for some places to start.)
  • Check with your doctor or other health care providers before you try a supplement. While your doctor might not know about all the products available, he or she may be able to keep you from making a dangerous mistake.
  • If you are shopping for a botanical (herb or other plant-based supplement), find a product that uses only the part of the plant that’s thought to be helpful. Avoid botanicals that have been made using the entire plant, unless the entire plant is recommended.
  • Does the label provide a way to contact the company if you have questions or concerns about their product? Reputable manufacturers will give contact information on the label or packaging of their products.
  • Avoid products that claim to be “miracle cures,” “breakthroughs,” or “new discoveries,” as well as those that claim to have benefits but no side effects, or are based on a “secret ingredient” or method. Such claims are almost always fraudulent, and the product may contain harmful substances, drugs, or contaminants.
  • Try to avoid mixtures of many different supplements. The more ingredients, the greater the chances of harmful effects. Mixtures also make it harder to know which substance is causing any side effects.
  • Start only one product at a time. Take note of any side effects you have while taking the product. If you have a rash, sleeplessness, restlessness, anxiety, nausea, vomiting, diarrhea, constipation, or severe headache, stop taking the supplement. Report any reaction to your doctor, and serious ones to the FDA (US Food and Drug Administration). (Below we cover “How to report serious reactions.”)
  • If you have any surgery or procedure planned, including dental surgery, talk with your surgeon about when you should stop taking supplements. Some supplements need 2 to 3 weeks to completely leave your body, and a few can cause serious problems during or after an operation.
  • During pregnancy or if you are breastfeeding, take only dietary supplements prescribed or approved by your doctor. Few, if any, of these products have been studied for safety; and their effects on a growing fetus or infant are largely unknown.
  • Do not take any self-prescribed remedy instead of the medicine prescribed by your doctor without talking about it with your doctor first.
  • Do not depend on any non-prescription product to cure cancer or any other serious disease. No matter what the claim, if it sounds too good to be true, it probably is.
  • Follow the dosage limits on the label. Overdoses can be deadly. Do not take a dietary supplement for any longer than recommended.
  • Never give a supplement to a baby or a child under the age of 18 without talking to the child’s doctor. A child processes nutrients and drugs differently from an adult, and the effects of many products in children are not known.
  • Avoid products that claim to treat a wide variety of unrelated illnesses. If a supplement claims that it can diagnose, treat, cure, or prevent disease, such as “cures cancer,” or “stops tumor growth,” the product is being sold illegally as a drug.

Be aware

Know the ingredients in the herbal medicines and dietary supplements you take. To help protect consumers, the FDA recommends that people using these products consider these suggestions:

  • Look for supplements with the USP or NF on the label. This indicates that the manufacturer of the product followed standards set by the US Pharmacopoeia in making the product.
  • Realize that the use of the term “natural” on an herbal product is no guarantee that the product is safe. Hemlock, for example, is natural but not safe.
  • Take into account the name and reputation of the manufacturer or distributor. Herbal products and other dietary supplements made by nationally known food or drug manufacturers are more likely to have been made under tight quality controls because these companies have a reputation to uphold.

If you need more information about the supplement, contact the manufacturer. Ask about the company’s manufacturing practices and the quality-control conditions under which the product was grown and/or made.

How to report serious reactions

If you or someone in your family suffers serious harm or illness (called an adverse event) due to a supplement, first call your doctor or other health care provider. The FDA considers an adverse event serious if it causes any of these:

  • Death
  • A life-threatening situation
  • Admission to a hospital or a longer-than-expected hospital stay
  • Permanent disability
  • A birth defect
  • The need for medical or surgical care to prevent permanent impairment or damage

After you have been treated, you or your doctor can report the adverse reaction to the FDA by calling 1-800-FDA-1088 (1-800-332-1088). Or you can go to the FDA’s MedWatch website at

When you talk to the FDA, you will need to tell them:

  • The name and telephone number of the person who got sick or had the problem. If that person cannot be reached, the FDA will need the name and number of another person who can give more information if needed
  • A description of the problem and how it was addressed
  • The name (including the brand or manufacturer) of the product

Along with the basic information above, you will be asked about the age, weight, and sex of the person who had the problem. The FDA staff will ask when and how much of the supplement was taken, and for how long. They will want to know where and when the product was purchased, lot number, and expiration date if available. This information is generally not needed, but if you can get it, it can help them follow up on the problem.

After you make a report to the FDA, you should notify the manufacturer of the product (listed on the label) and the store, seller, or Internet vendor where you bought the product.

The American Cancer Society medical and editorial content team

Our team is made up of doctors and oncology certified nurses with deep knowledge of cancer care as well as journalists, editors, and translators with extensive experience in medical writing.

Last Revised: March 31, 2015

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