Tips for Safely Using Nutritional Supplements

Nutritional supplements

Verywell / Anastasia Tretiak

Dietary supplements may be a helpful addition to your health routine, but it's important to keep in mind that the safety and effectiveness of supplements have not been proven scientifically and are largely unknown. To help choose your supplements wisely, keep these tips in mind.

Watch for Drug Interactions

A number of supplements may interact in harmful ways with prescription or over-the-counter drugs. For example, St. John's wort may alter the breakdown of many drugs including antidepressants and birth control pills. Vitamin K, ginkgo biloba, garlic, and vitamin E may interact with blood-thinners. That's why it's essential that you consult your physician before starting a supplement regimen or making changes to your treatment regimen or prescribed medications.

Your doctor may also be able to notify you of any other potential risks a supplement might pose to your health (especially if you're pregnant, have other medical conditions or are planning to have surgery), as well as offer guidance on the best dosage to take. If your doctor isn't comfortable with advising you on supplement use, ask if he or she can refer you to a qualified supplement-savvy health practitioner. But keep in mind that because of a lack of research on side effects, just how a supplement may interact with a medication often isn't known.

Seek out Certified Products

Look for supplements certified by the United States Pharmacopeia (USP), NSF International, or the United Natural Products Alliance, as it indicates a higher standard of quality assessment. (The USP's screening process, for instance, ensures that a product will break down properly and effectively release its ingredients into the body.) These organizations have a certification seal that is typically shown on the product packaging.

Check the Label

When shopping for an herbal supplement, it's important to verify which parts of the plant were used in its production. Different components can produce different effects, some of which can harm your health. For example, research shows that while the roots of the herb kava seem to be safe, its stem peelings and leaves may contain compounds that could be toxic to the liver. Talking with your doctor or herbalist can help you determine which plant parts to look for.

Take Heed of Side Effects

If you experience any adverse effects after taking a new supplement, discontinue its use immediately and contact your doctor and poison control center. Although some supplements may have minimal side effects, others are linked to serious side effects (such as kidney damage and gastrointestinal problems), especially when taken at excessive doses.

Also, it's important to know that most dietary supplements have not been tested for safety in pregnant women, nursing mothers or children.

Safety Not Guaranteed

The U.S. Food and Drug Administration does not regulate herbs and other dietary supplements in the same way it does prescription and non-prescription drugs. Unlike pharmaceutical manufacturers, who must prove a drug's safety and effectiveness prior to putting it on the market, supplement manufacturers are not required to prove the safety and effectiveness of a supplement before it is made available to consumers. (The Dietary Supplement Health and Education Act has exempted supplement manufacturers from these regulations).

Although product labels are supposed to list all ingredients accurately, in some cases, products sold to consumers have been found to be adulterated and mislabeled resulting in serious adverse effects. Even if a product is found to be adulterated, the recall is usually voluntary.

Supplements marketed for weight loss, sexual enhancement, and bodybuilding are among the types of supplements found to contain hidden ingredients and even undisclosed drugs not approved for over-the-counter use. Certain Ayurvedic and traditional Chinese medicine mixed herbal products may also be more likely to be contaminated or adulterated.


If you have allergies, particularly to plants, weeds, nuts, bee products, or pollen, you should consult your primary care provider before taking herbs or other supplements.


If you suspect that you've had an adverse reaction from a supplement, let your doctor know immediately. You may also call your local poison control center. Your doctor may report your experience to the FDA or you can also submit a report by completing a form online. You should also report your reaction to the supplement company and the retailer.

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  • Nerurkar PV, Dragull K, Tang CS. "In vitro toxicity of kava alkaloid, pipermethystine, in HepG2 cells compared to kavalactones." Toxicological Sciences 2004 79(1):106-11.