Medicine

Psittacosis (parrot fever): cause, symptoms, diagnosis, treatment Psittacosis Psittacosis is an uncommon bacterial infection transmitted from birds to humans, causing flu-like illness and sometimes pneumonia; treatable with antibiotics and preventable with s…

Psoriasis: causes, symptoms, types, and management Psoriasis Chronic immune-mediated skin condition marked by red, scaly plaques. Overview of causes, common types, triggers, diagnosis, treatments, self-care, and associated health issues.

Psychiatrist: medical specialist in mental health diagnosis and treatment Psychiatrist A psychiatrist is a physician trained to diagnose, treat, and help prevent mental disorders using medical, psychological, and social approaches, often including prescription medica…

Psychiatry: the medical specialty for diagnosing and treating mental disorders Psychiatry Psychiatry is the branch of medicine concerned with the assessment, diagnosis, treatment, and prevention of mental disorders, using biological, psychological and social approaches…

Psychoactive drugs: effects, categories, history, uses and societal issues Psychoactive drug Chemical substances that alter brain function and consciousness; overview of mechanisms, categories, therapeutic uses, risks, dependence treatment, history, and legal and ethical i…

Public health: population-level prevention, promotion, and policy Public health Public health studies and acts on the health of populations—preventing disease, extending life, and promoting wellbeing through organized societal, governmental and community effor…

Public health observatory: role, history and functions Public health observatory An overview of public health observatories — regional centres that collect and interpret health intelligence, their activities, history in the UK, and their role in policy and prac…

PubMed: free biomedical literature search service PubMed PubMed is a free search service run by the U.S. National Library of Medicine that provides access to a large collection of biomedical citations, abstracts, unique PMIDs, and links…

PubMed Central (PMC): free digital archive of biomedical literature PubMed Central PubMed Central (PMC) is a free, full-text digital repository of biomedical and life sciences journal articles maintained by the U.S. National Library of Medicine to promote open ac…

Pulmonary edema: causes, symptoms, diagnosis and treatment Pulmonary edema Pulmonary edema is accumulation of fluid in the lungs that interferes with breathing. This article explains its types, causes, signs, diagnosis, common treatments and key distincti…

Pulmonary embolism: causes, symptoms, diagnosis and treatment Pulmonary embolism Pulmonary embolism is an obstruction of blood flow to the lungs, most often from a traveling blood clot; this article explains causes, symptoms, diagnosis, management, and preventi…

Pulmonary hypertension Pulmonary hypertension is high blood pressure in the lung circulation that strains the right heart. It has multiple causes, variable symptoms, and treatments ranging from medicatio…

Pulmonology (Respiratory Medicine) Pulmonology Pulmonology is the medical specialty focused on the respiratory system, including diagnosis, treatment, prevention, and rehabilitation of lung and airway disorders across adults an…

Pulse (heartbeat): physiology, measurement, clinical meaning, and other uses Pulse The pulse is the rhythmic expansion of arteries with each heartbeat. This article covers its physiology, common measurement sites, clinical significance, heart sounds, and the unre…

Pus: composition, formation, clinical significance, and management Pus Pus is a protein- and cell-rich exudate that forms at sites of inflammation, most often from bacterial infection. This article explains its composition, common causes, appearance,…

Q fever (infection with Coxiella burnetii) Q fever Q fever is a zoonotic infection caused by Coxiella burnetii. It spreads from livestock and pets to people, primarily by inhaling contaminated aerosols; disease ranges from mild flu…

Qigong: Traditional Chinese Practice of Movement, Breath, and Mindfulness Qigong Qigong is a Chinese system combining posture, movement, breath and meditation to promote health, martial skill, and spiritual development. This article outlines forms, history, use…

Quack: the duck sound and the term for a charlatan Quack Overview of 'quack' as the sound ducks make and as a label for fraudulent or unscientific medical practitioners, with history, characteristics, examples and how to recognize or avo…

Quadrangular space of the shoulder: anatomy and clinical relevance Quadrangular space An anatomical interval in the posterior shoulder that transmits the axillary nerve and posterior circumflex humeral artery; important in shoulder injuries, surgical approaches, and…

Quarantine: Isolation to Prevent Spread of Disease and Pests Quarantine Quarantine is the controlled isolation of people, animals, plants, or areas to reduce transmission of infectious disease or invasive pests. It is used in public health, veterinary,…

Quinine: natural antimalarial alkaloid from Cinchona bark Quinine Quinine is a bitter alkaloid from Cinchona bark historically used to treat malaria and fever; it remains important medically and culturally as a medicine and flavouring agent.

Rabies: causes, transmission, symptoms, and prevention Rabies Rabies is a viral zoonotic disease that causes acute encephalitis and is almost always fatal once symptoms start. This article covers its agent, spread, clinical signs, prevention,…

Radiation therapy: principles, techniques, and clinical uses Radiation therapy Radiation therapy uses ionizing radiation to treat cancer and some non-malignant conditions. This article explains how it works, common techniques, clinical roles, planning and saf…

Radiology: Medical Imaging, Methods, History, and Applications Radiology Radiology is the medical specialty that produces and interprets images of the body to diagnose and treat disease, using modalities such as X‑ray, CT, MRI, ultrasound and PET.

Relapsing fever: cause, symptoms, transmission and management Relapsing fever Relapsing fever is an acute spirochetal infection by Borrelia species, spread by lice or ticks and marked by repeated febrile episodes; diagnosed by blood testing and treated with…

Remdesivir Remdesivir is an antiviral medication developed by Gilead Sciences that inhibits viral RNA polymerase. Given intravenously for hospitalized patients, it was repurposed for COVID-19…

Remission (medicine) Remission is a reduction or disappearance of disease signs and symptoms. It can be partial, complete, or molecular and is distinct from cure; it affects prognosis, monitoring and t…

Renal cell carcinoma: overview, presentation, diagnosis, and management Renal cell carcinoma A concise encyclopedia article on renal cell carcinoma, covering its types, causes, symptoms, diagnosis, treatment options and prognosis, with links to related topics.

Renal disease: causes, types, diagnosis and treatment Renal disease Overview of renal (kidney) disease: causes, common forms, symptoms, diagnosis, treatment options and prevention. Distinguishes acute vs chronic conditions and highlights key clinic…

Repetitive strain injury (RSI): causes, symptoms, diagnosis and management Repetitive strain injury Repetitive strain injury (RSI) is pain or dysfunction in muscles, tendons or nerves from repeated motion or sustained posture. This article explains features, causes, assessment, t…

Medical residency: postgraduate clinical training for physicians Residency (medicine) Residency is the supervised period of clinical training physicians undertake after medical school to develop specialty skills, competence, and eligibility for independent practice…

Respiratory care (respiratory therapy) Respiratory care Clinical specialty diagnosing, treating and managing breathing disorders. Practitioners include respiratory therapists who work with pulmonologists across acute, chronic and home s…

Respiratory disease Diseases of the respiratory system that impair breathing or gas exchange, from mild infections to chronic and life‑threatening disorders affecting lungs and airways.

Respiratory syncytial virus (RSV): causes, symptoms, prevention, and treatment Respiratory syncytial virus Comprehensive overview of respiratory syncytial virus (RSV): how it spreads, typical symptoms from colds to bronchiolitis, seasonal risk, prevention (hygiene, vaccines/monoclonals)…

Respiratory tract infection: causes, types, symptoms and prevention Respiratory tract infection Overview of respiratory tract infections: classification into upper and lower, common causes, symptoms, diagnosis, treatment approaches and public health importance.

Restless Legs Syndrome (RLS) Restless legs syndrome Restless legs syndrome is a neurological sensorimotor disorder characterized by an urge to move, uncomfortable sensations, and sleep disruption; often linked with low iron and othe…

Resuscitation: principles, methods and significance Resuscitation Overview of resuscitation: goals, basic and advanced methods (CPR, defibrillation), history, common causes, and why early intervention matters.

Retinal migraine: causes, symptoms, diagnosis, and management Retinal migraine Retinal migraine is a rare type of migraine that causes transient monocular visual disturbance or vision loss, often accompanied by headache; diagnosis requires exclusion of other…

Reye's syndrome — acute encephalopathy and liver dysfunction in children and adolescents Reye's syndrome Reye's syndrome is a rare but serious disorder of the brain and liver that can follow viral illness in children and teenagers and has been linked to aspirin exposure; early recogni…

Rhabdomyosarcoma: pediatric soft-tissue cancer arising from skeletal muscle precursors Rhabdomyosarcoma Pediatric rhabdomyosarcoma is a rare soft-tissue cancer from skeletal muscle precursors that can occur throughout the body. Learn about typical symptoms, diagnostic workup, multimo…

Rheumatic fever: causes, signs, diagnosis and prevention Rheumatic fever Rheumatic fever is an immune-mediated inflammatory illness that can follow untreated strep throat. It affects the heart, joints, skin and nervous system and can cause long-term val…

Rheumatism: overview, forms, history and clinical significance Rheumatism Rheumatism is a traditional umbrella term for disorders that cause pain, stiffness or inflammation of joints, muscles and connective tissue; it includes osteoarthritis, rheumatoid…

Rheumatoid arthritis: causes, symptoms, diagnosis and management Rheumatoid arthritis Rheumatoid arthritis (RA) is a chronic autoimmune disease that primarily affects joints. This article explains its features, causes, diagnosis, treatment, history and important con…

Rhytidectomy (Facelift): Overview, Techniques, Risks, and Recovery Rhytidectomy Rhytidectomy, commonly called a facelift, is a surgical procedure to reduce facial signs of aging by removing excess skin and repositioning tissues. Overview of techniques, risks,…

Rickets: childhood bone-softening due to vitamin D and mineral deficiency Rickets Rickets is a childhood disorder of impaired bone mineralization caused by vitamin D, calcium or phosphate deficiency. It produces bone pain, deformities and growth delay; treatment…

Right upper quadrant (abdomen) Anatomical and clinical overview of the right upper quadrant (RUQ) of the abdomen: boundaries, typical organs, examination clues, common causes of RUQ pain and important distinctio…

Ringworm (tinea): common fungal skin infections Ringworm Ringworm, or tinea, is a group of contagious fungal skin infections that produce itchy, often ring-shaped rashes. They affect scalp, feet, groin, nails, and body skin and are treat…

Rohypnol (flunitrazepam): medical uses, effects, misuse, and legal status Rohypnol An overview of Rohypnol (flunitrazepam): pharmacological effects, clinical uses, history, risks of misuse including drug-facilitated assault, and legal controls in various countrie…