Use & Practical Questions
What is known about herb doses, how long herbs have been studied, and why we give no universal dosage chart. Includes questions to ask a pharmacist.
Content last updated . This page has not been medically reviewed.
Safety first. Supplements can cause side effects and interact with medicines. Read mushroom safety and interactions before you use any mushroom product.
There is no universal dose for herbal products, and we do not publish a dosage chart. Amounts depend on the herb, the part, the form and the product. Doses in studies are study information, not recommendations. If you take a supplement, follow the instructions on the label. [1]
How long herbs have been studied (NIH summaries)
| Herb | Duration NIH describes |
|---|---|
| St. John's wort | Appears safe up to 12 weeks for most adults not taking medicine; some studies a year or more [2] |
| Turmeric (conventional oral) | Likely safe in recommended amounts for up to 2 or 3 months [3] |
| Valerian | Generally safe short term; apparent safety at 300 to 600 mg daily for up to 6 weeks in studies; long-term unknown [4] |
| Ginkgo extract | Used safely in studies as long as 6 years [5] |
| Garlic | Oral use safe in studies up to 7 years [6] |
| Saw palmetto | Used safely in studies up to 3 years [7] |
| Echinacea | Likely safe for most adults for short periods [8] |
A long study does not make long-term daily use right for you.
Food, tea and supplements differ
Most studies of ginger tested supplements, not foods. [9] Green tea as a beverage and green tea extract capsules have different safety records. [10]Combining products
Combining products adds risk because each has its own cautions. We found no sourced evidence on best timing, cycling or stacking in the NIH summaries we read, and absence of evidence is not safety.Tracking and talking to a pharmacist
Keep a short record of product, amount, start date, what you hoped to notice, and any new symptoms. Ask a pharmacist or clinician: Is this herb safe with my medicines? With my conditions? Should I stop before surgery? [1]References
- National Center for Complementary and Integrative Health (NIH). Using Dietary Supplements Wisely. Page last updated January 2019.
- National Center for Complementary and Integrative Health (NIH). St. John's Wort: Usefulness and Safety. Page last updated May 2025.
- National Center for Complementary and Integrative Health (NIH). Turmeric: Usefulness and Safety. Page last updated April 2025.
- National Center for Complementary and Integrative Health (NIH). Valerian: Usefulness and Safety. Page last updated May 2025.
- National Center for Complementary and Integrative Health (NIH). Ginkgo: Usefulness and Safety. Page last updated February 2025.
- National Center for Complementary and Integrative Health (NIH). Garlic: Usefulness and Safety. Page last updated February 2025.
- National Center for Complementary and Integrative Health (NIH). Saw Palmetto: Usefulness and Safety. Page last updated April 2025.
- National Center for Complementary and Integrative Health (NIH). Echinacea: Usefulness and Safety. Page last updated November 2024.
- National Center for Complementary and Integrative Health (NIH). Ginger: Usefulness and Safety. Page last updated February 2025.
- National Center for Complementary and Integrative Health (NIH). Green Tea: Usefulness and Safety. Page last updated February 2025.
Education, not medical advice. This page is for general information. It does not diagnose or treat any condition and is not a substitute for care from a qualified health professional. Natural does not automatically mean safe. Ask a clinician or pharmacist before changing your care, especially if you take medication, are pregnant or breastfeeding, or have a health condition.