Medicine

Ronald Reagan UCLA Medical Center Academic medical center on the UCLA campus in Los Angeles. A major teaching hospital and research center known for specialized care, training and a 2008 modern facility replacing t…

Rotavirus: cause, transmission, symptoms, prevention, and global impact Rotavirus Rotavirus is a common cause of acute gastroenteritis in young children worldwide. This article explains its biology, how it spreads, clinical features, treatment, vaccines and publ…

Rubella (German measles): causes, symptoms, congenital risks, and prevention Rubella Rubella is a generally mild viral infection that can cause serious birth defects if contracted during pregnancy; this article explains causes, spread, symptoms, diagnosis and preve…

Safe sex: practices, methods, and public health considerations Safe sex Overview of safe sex: definitions, common methods (barriers, contraception, testing, vaccination), risks reduced, historical context, practical tips and distinctions between preven…

Saline (medicine) Sterile aqueous solutions of sodium chloride used in medicine for infusion, irrigation and inhalation. Variants (isotonic, hypertonic, hypotonic) differ by salt concentration and c…

Salivary gland neoplasm Encyclopedic overview of neoplasms of major and minor salivary glands: anatomy, common benign and malignant types, clinical features, evaluation, treatment and follow-up.

Sarcoma: cancers of connective (mesenchymal) tissues Sarcoma Sarcoma is a group of malignancies arising from mesenchymal (connective) tissues such as bone, cartilage, fat and blood vessels. Subtypes, diagnosis, treatment and distinguishing f…

Scabies: causes, symptoms, transmission, diagnosis and treatment Scabies Scabies is a contagious skin infestation by the mite Sarcoptes scabiei. This article explains its causes, signs, diagnosis, treatment, prevention and public-health considerations i…

Scalpel: surgical cutting instrument, materials, history, and uses Scalpel A scalpel is a precise cutting instrument used in surgery and dissection. This article explains its design, materials, history, clinical uses, safety practices, and alternatives su…

Scarlet fever (scarlatina): causes, symptoms, treatment and history Scarlet fever Scarlet fever is an infectious illness caused by toxin‑producing Streptococcus pyogenes. It mainly affects children, produces a characteristic rash and is treated with antibiotics;…

Schistosomiasis (bilharzia): causes, symptoms, diagnosis, treatment and control Schistosomiasis Schistosomiasis is a parasitic disease caused by schistosome flatworms contracted from contaminated freshwater. It affects the urinary and intestinal tracts and can lead to chronic…

Schizophrenia: overview, symptoms, causes, diagnosis, and treatment Schizophrenia A neutral, concise overview of schizophrenia: its core features, typical course, causes, diagnostic distinctions, treatments and social impact for patients and families.

Schizophreniform disorder A psychotic condition marked by schizophrenia-like symptoms lasting between one and six months; covers diagnosis, common symptoms, possible causes, treatment approaches and distinc…

Scoliosis: overview, causes, diagnosis, and management Scoliosis Scoliosis is a lateral curvature of the spine that ranges from mild cosmetic asymmetry to severe deformity affecting function and breathing. Causes include idiopathic, congenital,…

Scrapie: a transmissible neurodegenerative disease of sheep and goats Scrapie Scrapie is a fatal, transmissible neurodegenerative disease of sheep and goats caused by misfolded prion proteins. This article explains signs, causes, history, diagnosis, control…

Scurvy: vitamin C deficiency — causes, symptoms, treatment, and history Scurvy Scurvy is a disease caused by lack of vitamin C. This article covers its causes, typical symptoms, diagnosis and treatment, historical role among sailors, and where it still appear…

Sebaceous hyperplasia: overview, signs, diagnosis, and treatment Sebaceous hyperplasia Sebaceous hyperplasia is a benign enlargement of oil glands causing small yellowish papules on the face. This article reviews appearance, causes, diagnosis, management, and when to…

Sedative: uses, types, risks, and management Sedative Sedatives are drugs that depress the central nervous system to produce calm or sleep. This article explains major types, common uses, mechanisms, risks (including dependence), and…

Selective serotonin reuptake inhibitor (SSRI): overview, uses, and effects Selective serotonin reuptake inhibitor SSRIs are a class of antidepressant drugs that increase serotonin signaling. Used widely for depression, anxiety and related disorders; they have characteristic benefits, risks, an…

Selsun Blue — medicated dandruff shampoo brand Selsun Blue Selsun Blue is a commercial line of anti-dandruff shampoos known for selenium sulfide formulations. The brand has evolved through several owners and is widely sold in mass-market r…

Sepsis: causes, signs, diagnosis, treatment and prevention Sepsis Sepsis is a life‑threatening condition caused by a dysregulated response to infection that can lead to organ failure. This article explains what sepsis is, how it develops, its sig…

Septic shock: causes, diagnosis, treatment, and outlook Septic shock Septic shock is a severe, life-threatening form of sepsis causing persistent hypotension and organ dysfunction. This article covers causes, pathophysiology, diagnosis, common treat…

Septicemic plague A severe, often rapidly fatal bloodstream infection caused by Yersinia pestis. Covers causes, signs, pathophysiology, diagnosis, treatment, history and prevention of this rare form…

Septum (biology): anatomical and structural partitions Septum A septum is a biological partition separating cavities or compartments in animals, plants, fungi and fossils. This article explains types, structure, functions, medical issues and…

Serotonin syndrome A potentially life‑threatening reaction from excess serotonin activity in the nervous system, often due to drug interactions or overdose; causes, symptoms, diagnosis, and managemen…

Sertraline: overview, mechanism, uses, history and safety Sertraline Sertraline is a commonly prescribed SSRI antidepressant used for depression, anxiety and related disorders. This article summarizes its action, indications, side effects, history a…

Severe acute respiratory syndrome (SARS): overview, history, and public health response Severe acute respiratory syndrome Severe acute respiratory syndrome (SARS) is a viral respiratory illness first identified in 2002–2003. This article summarizes its symptoms, transmission, outbreak history, diagnos…

Sexual abuse: definition, effects, vulnerable groups, and responses Sexual abuse An encyclopedic overview of sexual abuse: definitions, common forms, psychological and physical impacts, groups at higher risk, legal and support responses, and key distinctions su…

Sexual reassignment surgery: overview, procedures, history, and legal aspects Sexual reassignment surgery Comprehensive introduction to sexual reassignment surgery: what it comprises, common procedures for transfeminine and transmasculine patients, history, uses, risks, and legal and e…

Sexually Transmitted Infections: Causes, Symptoms, Testing and Prevention Sexually transmitted disease Comprehensive guide to sexually transmitted infections: causes, common symptoms, testing options, treatment, and prevention including condoms, vaccines, screening and partner care…

Sheba Medical Center (Tel HaShomer) — major Israeli medical complex Sheba Medical Center Sheba Medical Center at Tel HaShomer near Tel Aviv is one of Israel's largest tertiary hospitals, serving as a referral, research and teaching medical center with international out…

Shock (circulatory): causes, types, signs and emergency treatment Shock (circulatory) Circulatory shock is a life‑threatening failure of blood flow and tissue perfusion. This article explains causes, major types, clinical features, basic first aid and principles of…

Sick (illness, slang, and social meanings) Sick Overview of the term “sick”: medical meanings, common causes and symptoms, treatment and prevention, social and legal aspects, and linguistic uses including slang.

Sick building syndrome: causes, symptoms, history and prevention Sick building syndrome Overview of sick building syndrome (SBS), its typical symptoms, common causes such as poor ventilation and contaminants, historical context, and practical strategies to reduce risk…

Sickle-cell disease Inherited blood disorder in which abnormal hemoglobin causes red blood cells to deform, producing chronic anemia, painful crises, organ damage, and increased infection risk; varied…

Signs and symptoms (medical) Signs and symptoms Overview of medical signs and symptoms: definitions, differences, examples, historical context, role in diagnosis, and limitations in clinical practice.

Sildenafil (Viagra): mechanism, uses, history, and safety Sildenafil Sildenafil is a phosphodiesterase type 5 (PDE5) inhibitor used chiefly for erectile dysfunction and pulmonary arterial hypertension. This article covers how it works, uses, safety,…

Silicosis: causes, symptoms, history and prevention Silicosis Silicosis is an occupational lung disease caused by inhaling respirable crystalline silica dust. This article reviews causes, pathophysiology, clinical features, history, diagnosis…

Singapore General Hospital Singapore General Hospital (SGH) is the country’s oldest and largest tertiary referral and teaching hospital, a campus of specialty centres and a major hub for clinical care, educa…

Single-payer health care: definition, design, history and examples Single-payer health care Overview of single-payer health care: how it works, funding options, differences from multi-payer systems, benefits and concerns, and examples such as Canada.

Sinusitis: causes, symptoms, diagnosis and treatment Sinusitis Sinusitis is inflammation or infection of the paranasal sinuses causing congestion, facial pain, discharge and reduced sense of smell. Overview of types, causes, diagnosis, treatme…

Skin cancer: types, causes, detection, treatment and prevention Skin cancer A clear, balanced overview of skin cancer — its major types (melanoma, basal and squamous cell), causes such as UV exposure, common signs, diagnostic steps, treatments, prognosis,…

Skin cream: types, ingredients, uses and safety Skin cream Comprehensive overview of skin creams: formulations, common ingredients, types (moisturizers, medicated products, sunscreens), usage tips, safety issues and how to choose the right…

Skin graft (cutaneous grafting) Skin graft Overview of skin grafting: types, surgical techniques, history, indications, and complications, with distinctions between autografts, allografts, and other substitutes.

Skin tag (acrochordon): benign common skin growths Skin tag A skin tag is a small, soft, benign skin growth often attached by a narrow stalk. Common in adults, they occur where skin rubs together and are removed for irritation or cosmetic r…

Skull Bossing: Causes, Features, Diagnosis, and Management Skull bossing Skull bossing is a prominence or enlargement of parts of the skull (commonly the forehead). Overview of causes, clinical features, investigation, treatment, and how it differs from…

Sleep Apnea: Causes, Symptoms, Diagnosis, and Treatment Sleep apnea Guide to sleep apnea: causes (obstructive, central, mixed), symptoms and risk factors, diagnosis with sleep studies, and treatments including CPAP, oral appliances, and lifestyle m…

Sleep disorders: causes, common types, diagnosis, and treatment Sleep disorder Sleep disorders disrupt normal sleep patterns. This article explains common types, symptoms, diagnostic approaches (including polysomnography), causes, treatment options, and when…