Existing Conditions
A plain guide to existing health conditions and supplements: official cautions for liver, kidney, heart, diabetes, cancer and autoimmune conditions, with links to each guide.
Content last updated . This page has not been medically reviewed.
If you have a medical condition, tell your care team about every herb and supplement before you start one. NCCIH, part of the US National Institutes of Health, says supplements "may interact with your medications or pose risks if you have certain medical problems or are going to have surgery." [1] Not appearing on a list below does not mean a product is safe, and "natural" does not mean harmless. If someone collapses, is very confused, or has trouble breathing, call 911.
How to use this page
This page is the entry point for the conditions guides. Each row names what a source we read says, then links to the full page. Statements are labeled as documented by an official body, reported in case reports, or theoretical. For the general idea of those labels, see how interactions work. Nothing here tells you to start, stop or change a medicine. Ask the prescriber or a pharmacist.Conditions guides
| Condition | What a source we read says | Strength and type | Full guide |
|---|---|---|---|
| Liver disease or liver risk | Herbal and dietary supplement liver injury is a recognized problem; kava, bioavailable curcumin and black cohosh products have been linked to liver damage in reports. [2][3][4][5] | Reported cases; cause not always proven | More about Liver disease or liver risk → |
| Kidney disease | The National Kidney Foundation says herbal supplements can make kidney disease worse, interact with prescription medicines, or raise the risk of complications. [6] Aristolochic acid is a documented kidney toxin. [7] | Documented for aristolochic acid; others vary | More about Kidney disease → |
| Heart disease and high blood pressure | NCCIH says glycyrrhizin from licorice root has been linked to severe effects in people with hypertension or heart or kidney conditions. [8] FDA's 2004 final rule declares supplements containing ephedrine alkaloids adulterated. [9] | Documented by NCCIH and FDA | More about Heart disease and high blood pressure → |
| Diabetes | NCCIH says most supplements lack evidence of benefit for diabetes. [10] FDA found a hidden prescription drug that can cause low blood sugar in a product sold for diabetes. [11] | Documented by NCCIH and FDA | More about Diabetes → |
| Cancer | NCCIH says no complementary approach has been shown to prevent or cure cancer, and some herbs may make chemotherapy less effective. [12] | Documented by NCCIH; one observational study on delay of care | More about Cancer → |
| Autoimmune conditions | NCCIH says Asian ginseng may worsen autoimmune disorders. [13] The EU herbal monograph for echinacea does not recommend use in autoimmune diseases. [14] | Documented by NCCIH and EMA; research is early | More about Autoimmune conditions → |
| Bleeding disorders or blood thinners | NCCIH says ginkgo may increase bleeding risk in people taking anticoagulants such as warfarin, and Asian ginseng may interfere with clotting. [15][13] | Documented by NCCIH | More about Bleeding disorders or blood thinners → |
| Depression and other conditions treated with serotonin-acting medicines | NCCIH says St. John's wort taken with certain antidepressants or other serotonin-affecting drugs may increase serotonin-related side effects, which can be serious. [16] | Documented by NCCIH | More about Depression and other conditions treated with serotonin-acting medicines → |
Other conditions with their own pages
These pages are separate guides; we do not repeat their content here.- Thyroid conditions
- Mental health conditions, including bipolar disorder and anxiety
- Epilepsy and seizure risk
- Eating disorders and weight-loss products
- Allergies and asthma
- Alcohol use disorder
- Surgery and procedures
What we did not find
Proper evidence not found for a single list that covers every condition and every product. We looked for one in NCCIH, MedlinePlus and NHS pages. The sources we read treat conditions one at a time, so this page does the same.Before any change
Bring a written list of everything you take. The talking-with-a-health-professional guide shows what to bring and ask. For quality problems such as undeclared ingredients, see product quality and contamination.Frequently asked questions
Does having a health condition mean I can never use a supplement?
No source we read says that. They say to check first with a clinician or pharmacist, because some products interact with medicines or affect certain conditions. [1]
Why are the pages split by condition?
Cautions differ a lot. For example, NCCIH describes licorice cautions for people with heart or kidney conditions, while the cancer guidance focuses on interference with treatment. [8][12]
Are herbal products tested for people with my condition?
The National Kidney Foundation says studies of herbal supplements often do not include people living with kidney disease, so good information can be hard to find. [6]
What if a product says it treats my condition?
Treat it with caution. NCCIH and FDA warn about products promoted as diabetes or cancer "cures," and about harm from using them instead of treatment. [10][12]
Where do I report a bad reaction?
References
- National Center for Complementary and Integrative Health (NCCIH, US). Using Dietary Supplements Wisely. Read 2026-10-23.
- NCCIH (US). Kava: Usefulness and Safety. Read 2026-10-23.
- NCCIH (US). Turmeric: Usefulness and Safety. Read 2026-10-23.
- NCCIH (US). Black Cohosh: Usefulness and Safety. Read 2026-10-23.
- Halegoua-DeMarzio D, Navarro V. Challenges in herbal-induced liver injury identification and prevention. Liver Int. 2025;45(3):e16071. Read 2026-10-23.
- National Kidney Foundation (US). Herbal Supplements and Kidney Disease. Last updated September 5, 2025. Read 2026-10-23.
- Lai MN, et al. Chinese Herbs Containing Aristolochic Acid Associated with Renal Failure and Urothelial Carcinoma: A Review from Epidemiologic Observations to Causal Inference. BioMed Research International (PMC). Open-access review. Read 2026-10-23.
- NCCIH (US). Licorice Root: Usefulness and Safety. Read 2026-10-23.
- US Food and Drug Administration (FDA). Small Entity Compliance Guide: Final Rule Declaring Dietary Supplements Containing Ephedrine Alkaloids Adulterated Because They Present an Unreasonable Risk. Read 2026-10-23.
- NCCIH (US). Diabetes and Dietary Supplements: What You Need To Know. Read 2026-10-23.
- US FDA. Questions and Answers: FDA alerts companies to stop the illegal sale of products claiming to treat diabetes. Read 2026-10-23.
- NCCIH (US). Cancer and Complementary Health Approaches: What You Need To Know. Read 2026-10-23.
- NCCIH (US). Asian Ginseng: Usefulness and Safety. Read 2026-10-23.
- European Medicines Agency, Committee on Herbal Medicinal Products (HMPC). European Union herbal monograph on Echinacea purpurea (L.) Moench, herba recens, final, EMA/HMPC/48704/2014. 24 November 2015. Read 2026-10-23.
- NCCIH (US). Ginkgo: Usefulness and Safety. Read 2026-10-23.
- NCCIH (US). St. John’s Wort: Usefulness and Safety. Read 2026-10-23.
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.