Use & Practical Questions

Short answer. There is no universal amount for herbal products, and this site does not publish a dosage chart. What works in a study depends on the herb, the plant part, the form and the product, and a supplement bought in a store may differ in important ways from the product tested in a study. [1] Any number on this page is study information or official-source information. It is not advice for a person. A pharmacist or clinician decides what is right for you.

Studied duration and amounts, as NIH describes them

The National Center for Complementary and Integrative Health (NCCIH, part of the US National Institutes of Health) states how long some herbs have been used safely in research. Those statements describe study volunteers, a particular product and a particular period. They do not describe your situation.

A long study does not make long-term daily use right for you. Evidence label for these durations: they describe safety observed in research, not proof that a herb works.

Why the form and the product change the answer

• Food, drink and supplement are different things. For ginger, most studies tested dietary supplements rather than foods. [9] For green tea, no safety concerns were reported for the drink in adults, while liver injury has been reported mainly with extracts in tablet or capsule form. [10] See green tea.
• "Standardized" is not a guarantee. NCCIH says the words "standardized," "verified" or "certified" do not necessarily guarantee product quality or consistency. [1]
• Labeled and actual contents can differ. The NIH LactMed entry for St. John's wort notes that differences are often found between labeled and actual ingredients or their amounts, and that test results for one product may not apply to others. [11] See reading an herbal supplement label and quality testing.
• Follow the label, and report problems. NCCIH advises following label instructions and, if side effects occur, stopping and contacting a health care provider. [1]

Combining products

Supplements can change how medicines work and can have side effects of their own. [12] FDA gives an example: warfarin, ginkgo, aspirin and vitamin E can each thin the blood, and taking them together may raise the chance of internal bleeding or stroke. [13] Proper evidence not found, in the NCCIH, FDA and NIH pages we read, for "best timing," cycling or stacking schedules. Absence of guidance is not a sign of safety. See amounts and duplicate ingredients.

Situations that call for extra care

• Surgery. Supplements may increase bleeding risk, affect response to anesthetics or change heart rate and blood pressure, so NCCIH advises telling providers as far in advance as possible. [14] More at herbs before and after surgery.
• Pregnancy, breastfeeding and children. Many dietary supplements have not been tested in pregnant women, nursing mothers or children. [1] See herbs during pregnancy.
• Medicines with a narrow therapeutic range (for example warfarin, digoxin, cyclosporine). NCCIH says people on these should take special care to tell their providers about herbal supplements. [12]

Keep a record and ask

Bring a written list of everything you take, how often, and the amounts on the label. [12] The worksheet and the question checklist are ready to use. To look up a herb yourself, start with how to check a herb for interactions.