Forms & Preparations
Why the form of an herb matters: teas, extracts, capsules, oils and bioavailable formulas differ in studies and in risk. Uses NIH examples. No recipes.
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.
Herbal products come as teas, extracts, tablets, capsules, powders and other forms. [1] A finding about one form does not automatically apply to another. NIH's own summaries show why.
| Herb | Form difference NIH describes |
|---|---|
| Turmeric | Kitchen turmeric, conventional turmeric or curcumin supplements, and curcumin products made to be absorbed better are different. The highly absorbable products have been linked to liver damage. Many products also contain piperine from black pepper. [2] |
| Green tea | Beverage and extract supplements differ. No safety concern was reported for the drink, while liver injury has been reported mainly with tablet and capsule extracts. Most cholesterol studies used extracts. [3] |
| Elderberry | Cooked berries and products differ from raw or unripe berries and other tree parts, which are poisonous. [4] |
| Garlic | Garlic taken by mouth in studies differs from raw garlic on the skin, which can cause burns. [5] |
| Ginger | Most studies tested supplements, not foods. Topical ginger has not been shown to help knee osteoarthritis. [6] |
| Ginkgo | Leaf extract is used in studies; seeds and crude plant are toxic. [7] |
| Echinacea | Species, plant part and growing conditions can change an extract's activity. [8] |
| Peppermint | The oil and the leaf tea are different products with different evidence. See Peppermint oil. |
| Milk thistle | Extracts are measured for silymarin, and quality problems have been found in products. [9] |
Teas, extracts, capsules and powders
We do not describe how to make tinctures, decoctions or glycerites, because we could not verify methods and safe amounts from the sources we can read, and homemade preparations vary in strength. Search interest in making tinctures is real, and this is a gap we have chosen not to fill without verified sources.Single herbs and blends
A blend adds uncertainty about what you are getting, and NIH notes that when studies test a chamomile product that also contains other herbs, it is hard to know chamomile's exact role. For chamomile, certain herb combinations may help children's diarrhea and infant colic, but chamomile alone has not been shown to. [10]Oils
Essential oils are a different category with their own safety rules; see Essential Oils & Aromatherapy.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). Turmeric: Usefulness and Safety. Page last updated April 2025.
- National Center for Complementary and Integrative Health (NIH). Green Tea: Usefulness and Safety. Page last updated February 2025.
- National Center for Complementary and Integrative Health (NIH). Elderberry: Usefulness and Safety. Page last updated November 2024.
- 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). Ginger: Usefulness and Safety. Page last updated February 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). Echinacea: Usefulness and Safety. Page last updated November 2024.
- National Center for Complementary and Integrative Health (NIH). Milk Thistle: Usefulness and Safety. Page last updated February 2025.
- National Center for Complementary and Integrative Health (NIH). Chamomile: Usefulness and Safety. Page last updated November 2024.
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.