General health information
- MedlinePlus — Plain-language explanations of conditions, tests and medicines from the US National Library of Medicine. The best first stop for almost any medical term.
- Centers for Disease Control and Prevention — US public-health guidance: infectious disease, vaccination schedules, chronic disease data and travel health.
- National Institutes of Health — The umbrella body for US biomedical research, and the gateway to its 27 institutes and centers.
- MyHealthfinder (health.gov) — Personalised, plain-language prevention advice from the US Department of Health and Human Services — what screening and vaccines are recommended for someone your age.
- US Food and Drug Administration — Drug and device approvals, safety communications, recalls, and the official labelling for approved medicines.
Heart and circulation
- American Heart Association — Patient-facing guidance on blood pressure, cholesterol, heart failure, stroke and CPR, alongside the guidelines clinicians use.
- National Heart, Lung, and Blood Institute — NIH institute covering heart, lung, blood and sleep disorders, with well-written explainer pages.
Diabetes and metabolic health
- American Diabetes Association — Living-with-diabetes guidance and the annual Standards of Care that shape US diabetes treatment.
- National Institute of Diabetes and Digestive and Kidney Diseases — NIH institute covering diabetes, obesity, digestive disease, liver disease and kidney disease. Consistently clear patient material.
Cancer
- National Cancer Institute — The most authoritative US source on cancer types, treatment, screening and clinical trials, with separate patient and professional versions of each summary.
- American Cancer Society — Screening recommendations, treatment explanations and practical support for patients and families.
Mental health
- National Institute of Mental Health — NIH institute with evidence-based overviews of depression, anxiety, bipolar disorder, PTSD and more.
- National Alliance on Mental Illness — Peer support, family education and practical navigation help for people living with mental illness.
- SAMHSA — The US Substance Abuse and Mental Health Services Administration — treatment locators, crisis resources and substance use guidance.
Sleep
- Sleep Education (American Academy of Sleep Medicine) — Patient-facing sleep information from the professional body that accredits US sleep centers — insomnia, sleep apnea, circadian disorders.
Bones and joints
- Arthritis Foundation — Osteoarthritis, rheumatoid arthritis and related conditions: symptoms, treatment options and day-to-day management.
- Bone Health & Osteoporosis Foundation — Formerly the National Osteoporosis Foundation. Bone density, fracture risk, and prevention across the lifespan.
Lungs and allergy
- American Lung Association — Asthma, COPD, lung cancer, air quality and smoking cessation support.
- American Academy of Allergy, Asthma & Immunology — Allergy, asthma and immunology guidance, including anaphylaxis and food allergy.
Kidney and liver
- National Kidney Foundation — Chronic kidney disease, eGFR and what the numbers mean, dialysis and transplantation.
- American Liver Foundation — Fatty liver disease, hepatitis, cirrhosis and liver health.
Ageing
- National Institute on Aging — NIH institute covering healthy ageing, Alzheimer disease and dementia, caregiving and later-life health.
Prevention and screening
- US Preventive Services Task Force — The independent panel whose graded recommendations determine which screening tests are advised, and at what age.
- ClinicalTrials.gov — The registry of clinical studies worldwide. Useful for finding a trial, and for checking whether a claimed result was ever registered.
International
- World Health Organization — Global health guidance, outbreak information and international standards.
- NHS (United Kingdom) — Among the clearest patient-facing health libraries anywhere, and useful regardless of where you live — though services and numbers described are UK-specific.
- Cochrane — Systematic reviews that pool the available trials on a question. The closest thing to a bottom line on what the evidence says.
How an organisation gets onto this list
We include an organisation when it publishes health information under a named editorial or scientific process, when its funding and governance are disclosed, and when its patient-facing material is accurate enough that we would be comfortable citing it directly. Government health agencies, NIH institutes, national professional bodies and established disease-specific charities meet that bar. Commercial health sites, supplement sellers and clinics that publish marketing as education do not, however well designed they are.
Being on this list is not an endorsement of every position an organisation takes, and guidance genuinely differs between them — screening age recommendations are a common example. Where sources disagree, our guides say so rather than picking one silently.