Medicine

Hyponatremia Hyponatremia is low blood sodium causing water shifts into cells; symptoms range from mild to life‑threatening. It results from excess water, sodium loss, or disease and requires c…

Hypopharyngeal cancer: overview, signs, diagnosis and management Hypopharyngeal cancer Hypopharyngeal cancer is a rare head and neck malignancy arising where the larynx and esophagus meet. This article outlines anatomy, symptoms, causes, diagnosis, treatment options…

Hypotension (Low Blood Pressure) Hypotension Hypotension is abnormally low arterial blood pressure. This article explains definitions, common causes, symptoms, diagnosis, management, and when to seek medical attention.

Hypothermia: causes, symptoms, emergency care and prevention Hypothermia Comprehensive overview of hypothermia: definition, stages, common signs, first aid, hospital treatments, risk factors, prevention, and when to seek urgent medical help.

Hypothyroidism: causes, symptoms, diagnosis and treatment Hypothyroidism Hypothyroidism is a condition in which the thyroid gland produces insufficient thyroid hormones. This article explains causes, common signs, diagnostic tests, treatment options and…

Hypoxia (medical) Hypoxia is inadequate oxygen supply at the tissue level. Covers types, causes, symptoms, diagnosis, treatment, prevention, and distinction from related terms.

Hysterectomy — surgical removal of the uterus Hysterectomy Hysterectomy is an operation to remove the uterus. This article explains types, reasons, approaches, effects on fertility and hormones, risks, recovery, and alternatives.

Hysterotomy abortion A surgical second‑trimester abortion in which the uterus is opened and the pregnancy removed; a rare, higher‑risk procedure reserved for cases where other methods are unsafe or imp…

Ibuprofen: overview, mechanism, history, uses and precautions Ibuprofen Ibuprofen is a widely used nonsteroidal anti-inflammatory drug (NSAID) for pain, inflammation and fever. This article summarizes its action, common uses, history, dosing principles…

International Classification of Diseases (ICD) ICD The ICD is a WHO-maintained system of alphanumeric codes for diseases, symptoms, injuries and health-related factors used for statistics, clinical records, billing, research and in…

Ice Bucket Challenge A 2014 social-media fundraising phenomenon in which participants poured ice water over themselves to raise awareness and donations for amyotrophic lateral sclerosis (ALS).

Immunization: Principles, Types, History, and Public Health Impact Immunization Comprehensive overview of immunization: how it stimulates immunity, main vaccine types and development, safety and monitoring, program logistics, herd immunity, and public-health b…

Immunosuppressant drugs: overview, types, uses, and safety considerations Immunosuppressant drugs Drugs that reduce immune activity to prevent organ rejection and treat autoimmune disease; classes, mechanisms, clinical uses, risks, and monitoring explained for general readers.

Immunosuppression: causes, uses, risks, and clinical management Immunosuppression Overview of immunosuppression: intentional and pathological reduction of immune activity, common agents, clinical uses (transplant, autoimmune disease), risks, monitoring, and nota…

Impetigo (school sores): a common contagious skin infection Impetigo Impetigo is a contagious superficial bacterial skin infection, most often affecting young children. This article covers causes, signs, treatment, prevention and when to seek care.

In vitro fertilisation (IVF): overview, procedure, uses and considerations In vitro fertilisation IVF is a laboratory procedure that enables fertilisation of eggs by sperm outside the body. This article explains how IVF works, its main steps, variations, indications, risks and…

Incubation period (infectious diseases) Incubation period Interval between exposure to a pathogen and the onset of symptoms; varies by agent and host and informs quarantine, contact tracing, surveillance and modeling.

Indigestion (Dyspepsia): Symptoms, Causes, Diagnosis and Management Indigestion Indigestion, or dyspepsia, describes discomfort in the upper abdomen. This article explains symptoms, common causes, diagnostic approach, treatment options, and prevention strategi…

Infection: causes, development, transmission, diagnosis and prevention Infection An infection occurs when disease-causing agents invade and multiply in body tissues. This article explains agents, how infections develop, transmission routes, diagnosis, treatment…

Inflammation: causes, signs, mechanisms, history and clinical relevance Inflammation A concise overview of inflammation: what it is, how it works, classic signs, historical notes, clinical examples and approaches to management and prevention.

Influenza (seasonal flu): causes, symptoms, transmission, and prevention Influenza Overview of seasonal influenza: causes (influenza A and B), common symptoms, modes of transmission, high‑risk groups, and prevention with vaccination, hygiene, and available treatm…

Informed consent Informed consent is the process by which a person voluntarily agrees to medical treatment or participation in research after understanding relevant information, risks, benefits and…

Inhaler (medical device) Inhaler A portable device that delivers medication by inhalation to treat respiratory conditions such as asthma and COPD. Covers types, components, correct technique, history, uses, and pr…

Injection (medical): types, uses, technique and safety Injection Overview of medical injections: common routes, clinical uses, administration technique, safety precautions, complications, and considerations for different patients and settings.

Inoculation (Variolation): History, Methods, and Legacy Inoculation Inoculation, or variolation, was an early practice of inducing protection against smallpox by deliberate exposure to infected material. This article summarizes methods, history, ri…

Insulin: regulation of blood sugar, structure, history, and medical use Insulin Insulin is a peptide hormone from the pancreas that regulates blood glucose and metabolism. This article covers its structure, physiology, discovery, therapeutic use, and clinical…

Insulin lispro (Humalog) — rapid-acting insulin analog Insulin lispro Insulin lispro (Humalog) is a rapid-acting insulin analog used to control blood glucose around meals in people with type 1, LADA, and insulin-requiring type 2 diabetes. Fast onset…

Insulin pump: portable insulin delivery, components, uses and considerations Insulin pump Overview of insulin pumps — how they work, components, history, benefits, risks, and integration with glucose monitoring and carb counting for diabetes management.

Insulin resistance: causes, mechanisms, and clinical importance Insulin resistance Insulin resistance is a metabolic state in which tissues respond poorly to insulin, raising blood glucose and increasing risk for type 2 diabetes and related cardiovascular and met…

Intensive Care Unit (ICU): purpose, organization, types and history Intensive care unit A concise overview of intensive care units: definition, core functions, staffing, common equipment and interventions, unit types, admission principles, complications, ethical issue…

Interleukin‑2 (IL‑2) Interleukin 2 Interleukin‑2 is a cytokine that promotes T cell and natural killer cell activity. Recombinant IL‑2 (aldesleukin) is used in cancer immunotherapy and is the subject of ongoing rese…

Internal medicine: scope, training, subspecialties, and clinical role Internal medicine Internal medicine is the medical specialty focused on diagnosing, preventing and treating adult diseases of internal organs; includes general internists and multiple subspecialties…

Intersex: biological variations in sex characteristics, care, and social issues Intersex Intersex describes a range of natural variations in chromosomal, gonadal, or anatomical sex characteristics. This article covers causes, terminology, medical care, history, and soc…

Interstitial cystitis (bladder pain syndrome) Interstitial cystitis Chronic condition causing bladder pain, urinary urgency and frequency. Also called bladder pain syndrome; diagnosis is clinical and treatment focuses on symptom management and impr…

Interventional Radiology: Principles, Techniques, and Clinical Uses Interventional Radiology Interventional radiology uses medical imaging to guide minimally invasive diagnostic and therapeutic procedures with needles, catheters, and other small instruments.

Intracerebral hemorrhage (ICH): overview, causes, symptoms, and care Intracerebral hemorrhage Intracerebral hemorrhage (ICH) is bleeding into the brain parenchyma or ventricles. This article explains presentation, causes, diagnosis, treatment approaches, prognosis, and how…

Intracranial aneurysm (brain aneurysm): causes, signs, diagnosis, treatment Intracranial aneurysm Intracranial aneurysm: a focal dilation of a cerebral artery. Covers types, causes, clinical presentation, diagnostic imaging, emergency care, treatment options, complications and…

Intracranial hemorrhage Bleeding inside the skull that damages brain tissue; types, causes, symptoms, diagnosis, treatment, outcomes and prevention explained for a general audience.

Intravenous therapy (IV therapy) Intravenous therapy Intravenous therapy is the medical administration of fluids, medications or blood directly into a vein. It includes types, devices, common uses, risks and brief historical context.

Iodine deficiency: causes, effects, prevention and public‑health significance Iodine deficiency A shortage of dietary iodine leading to inadequate thyroid hormones, goiter and preventable developmental impairment; commonly addressed by iodized salt and population programs.

Iron-deficiency anemia: causes, symptoms, diagnosis, treatment, and prevention Iron deficiency anemia Comprehensive overview of iron-deficiency anemia: causes, mechanisms, risk groups, symptoms, diagnosis, treatment options, prevention, public-health aspects and when to seek care.

Ischaemia: reduced blood supply and its medical significance Ischaemia Ischaemia (ischemia) is reduced or blocked blood flow to a tissue or organ, causing oxygen deprivation and cellular injury. Causes, pathophysiology, clinical features, diagnosis, t…

Ischemic colitis Ischemic colitis is injury and inflammation of the large intestine caused by reduced blood flow. It most commonly affects older adults and ranges from transient mucosal damage to l…

Isolation (health care) In health care, isolation is the practice of separating infected or potentially infectious patients to prevent disease spread; it includes types, procedures, history, and how it di…

Itch (Pruritus): sensation, causes, neural mechanisms, and management Itch Itch (pruritus) is an unpleasant skin sensation that provokes the urge to scratch. This article explains its characteristics, neural pathways, causes, history, clinical importance…

Jaundice (Icterus): causes, signs, diagnosis and management Jaundice Jaundice (icterus) is yellowing of the skin and eyes due to raised bilirubin. This article explains causes, how bilirubin metabolism is altered, common presentations, diagnosis, tr…

Jeotgalicoccus huakuii — a moderately halophilic coccoid bacterium Jeotgalicoccus huakuii A concise overview of Jeotgalicoccus huakuii: Gram-positive, coccoid bacteria in the Staphylococcaceae family, moderately halophilic and facultatively anaerobic, with notes on trai…

Jet lag: causes, symptoms, and practical management Jet lag Jet lag is a temporary mismatch between the body's internal clock and a new local time after rapid travel across time zones. Learn causes, symptoms, and practical mitigation strate…