Medicine

Pharmacotherapy: principles, practice, and development Pharmacotheraphy Pharmacotherapy is the medical use of drugs to prevent, diagnose, or treat disease. This article explains its scope, components, history, common applications, safety considerations…

Pharmacy: practice, services, and role in health care Pharmacy Overview of pharmacies: retail and clinical roles, common services, prescription rules, pharmacist responsibilities, and pharmacy as a scientific discipline.

Pharynx: structure, function, and clinical significance Pharynx The pharynx is the muscular tube at the back of the throat that links the nasal and oral cavities with the larynx and esophagus. It plays key roles in breathing, swallowing, speech…

Phencyclidine (PCP): Overview, Effects, History, and Risks Phencyclidine Phencyclidine (PCP) is a dissociative anesthetic that became an illicit hallucinogen; it produces dissociation, perceptual changes and carries acute medical risks and potential lon…

Phenylketonuria (PKU): causes, diagnosis, and management Phenylketonuria Inherited metabolic disorder caused by inability to break down phenylalanine. Detected by newborn screening and managed mainly by dietary restriction to prevent intellectual disabi…

Phlegm: the respiratory sticky secretion Phlegm Phlegm is a viscous secretion produced by mucous membranes in the airways. This article explains its composition, role in health and disease, historical view, clinical signs and co…

Physical dependence (drug-related physiological dependence) Physical dependence Physical dependence is a physiological state in which regular use of a substance produces withdrawal symptoms when the substance is reduced or stopped; it differs from addiction an…

Physician (Medical Doctor): Role, Training, and Specialties Physician A physician is a medically trained professional who diagnoses, treats and helps prevent illness. This article explains roles, education, specialties, history and distinctions in cl…

Physiotherapy (Physical Therapy): Principles, Techniques and Specialties Physiotherapy Physiotherapy, also called physical therapy, is a health profession focused on restoring and maintaining movement and function through assessment, exercise, manual therapy, educati…

Pica (eating disorder): definition, causes, diagnosis, and management Pica (disorder) Pica is a condition characterized by persistent consumption of non-food items or atypical food preparations. This article explains symptoms, causes, complications, diagnosis, treat…

Pitié‑Salpêtrière Hospital, Paris Pitié-Salpêtrière Hospital Major teaching and research hospital in Paris known for neurology, psychiatry and a long history as a public hospice and medical center.

Pituitary adenoma A pituitary adenoma is a usually benign tumor of the pituitary gland that can affect hormone production and cause mass effects; management ranges from observation to medication, su…

Placebo: inert treatments, the placebo effect, and their role in medicine Placebo Overview of placebos — inactive treatments used in research and sometimes care; how placebo effects arise, history, uses in trials, ethical concerns, and related phenomena such as…

Plague doctor costume Distinctive protective outfit used by physicians in early modern Europe treating plague victims, notable for its beaked mask, long protective coat, gloves, hat and staff; linked to…

Plasmodium falciparum: biology, disease, and global impact Plasmodium falciparum Plasmodium falciparum is a protozoan parasite that causes the most severe form of human malaria. This article summarizes its biology, clinical effects, diagnosis, treatment, preven…

Plastic surgery: reconstructive and cosmetic procedures, techniques, and considerations Plastic surgery Comprehensive overview of plastic surgery: goals, common reconstructive and cosmetic procedures, tissues and techniques, risks, patient selection, training, ethics and recent devel…

Pleurisy (pleuritis): inflammation of the pleural lining Pleurisy Pleurisy, or pleuritis, is inflammation of the pleura that causes sharp, breathing-related chest pain. Causes include infections, embolism, autoimmune disease and malignancy; diagn…

Pneumonia: causes, symptoms, diagnosis, treatment and prevention Pneumonia Pneumonia is an infection of the lungs that inflames air sacs and reduces oxygen uptake. This article explains causes, symptoms, diagnosis, treatment, prevention and key facts.

Pneumothorax (collapsed lung): causes, types, diagnosis and treatment Pneumothorax Pneumothorax is air in the pleural space causing lung collapse. This article explains causes, types (including tension), symptoms, investigation, treatment options and outcomes.

Poison: definition, types, mechanisms, and public health implications Poison Comprehensive overview of poisons: how they act, exposure routes, differences from toxins and venoms, classifications (carcinogens, mutagens, teratogens), antidotes, and safety mea…

Polio vaccine Vaccines that prevent poliomyelitis, using either inactivated or weakened poliovirus. They transformed global health, driving dramatic reductions in polio cases and forming the fou…

Poliomyelitis (polio): overview, course, prevention and history Poliomyelitis Poliomyelitis is an infectious viral disease that can cause paralysis and death. Widespread vaccination has reduced cases by over 99% and remains central to eradication efforts.

Polymyalgia rheumatica: causes, symptoms, diagnosis, and management Polymyalgia rheumatica Polymyalgia rheumatica (PMR) is an inflammatory condition of older adults causing aching and morning stiffness in the shoulders, hips and neck. It is diagnosed clinically with bloo…

Polyp (medicine): types, detection, treatment and clinical importance Polyp (medicine) A polyp is an abnormal tissue growth projecting from a mucous membrane. This article explains locations, types (pedunculated vs sessile), diagnostic methods, treatment options and…

Porphyria: causes, types, symptoms, diagnosis and management Porphyria Porphyria is a group of inherited and acquired disorders of heme production. This article summarizes its mechanisms, clinical forms, triggers, diagnosis and current treatment appro…

Positron Emission Tomography (PET): Principles, Uses, and Limitations Positron emission tomography Positron emission tomography (PET) is a medical imaging method that visualizes physiological processes using short‑lived radioactive tracers. Common applications include cancer det…

Prader–Willi syndrome Prader–Willi syndrome is a genetic neurodevelopmental disorder with infant hypotonia, later excessive appetite and obesity risk, short stature, hypogonadism, cognitive and behavior…

Pre-ejaculate (pre-ejaculatory fluid) Pre-ejaculate Clear fluid produced during male sexual arousal that can lubricate, neutralize urethra acidity, and—sometimes—carry sperm or pathogens; varies between individuals.

Precancerous condition (premalignant): overview, examples, diagnosis and management Precancerous condition A precancerous (premalignant) condition is tissue change that is not yet cancerous but has increased risk of progressing to malignancy. Overview, characteristics, common examples,…

Prednisone — synthetic corticosteroid for inflammatory and immune conditions Prednisone Prednisone is a synthetic glucocorticoid used to reduce inflammation and suppress immune activity. It treats diverse conditions from asthma and autoimmune diseases to sarcoidosis,…

Premature birth (preterm birth): causes, risks, outcomes and care Premature birth Premature (preterm) birth occurs when a baby is born before 37 completed weeks of gestation. This article covers definition, causes, risks, clinical care, prevention and the global…

Premature ejaculation (PE) Premature ejaculation Premature ejaculation (PE) is a common male sexual problem in which ejaculation happens sooner than desired. This article explains features, causes, diagnosis, treatments, and how…

Prenatal diagnosis: methods, applications, risks, and ethical considerations Prenatal diagnosis Comprehensive overview of prenatal diagnosis: screening and diagnostic methods, conditions evaluated, clinical uses, risks and timing, counseling, and ethical and legal concerns.

Prescription: medical orders for medicines and treatment Prescription A prescription is a clinician's written or electronic instruction for a patient's medication or care, governing what drug, dose, route and duration are required and how it may be s…

Prevalence (epidemiology) Prevalence Prevalence is the proportion of a population that has a particular condition at a specified time or period. It describes how common a disease or characteristic is and differs from…

Primary care doctor (primary care physician) Primary care doctor An overview of primary care doctors: roles, training, services, how they differ from specialists, when to see one, and their role in coordinated, preventive medical care.

Primary central nervous system lymphoma A rare type of extranodal non-Hodgkin lymphoma confined to the brain, eyes, leptomeninges or spinal cord; diagnosis, features, treatment, and notable distinctions.

Primary peritoneal carcinoma: overview, diagnosis, treatment, and distinctions Primary peritoneal carcinoma Primary peritoneal carcinoma is a rare cancer of the abdominal lining closely related to high‑grade serous ovarian carcinoma. This article explains its pathology, presentation, dia…

Prion disease (transmissible spongiform encephalopathy) Prion disease Prion diseases are rare, progressive neurodegenerative disorders caused by misfolded prion proteins. They are transmissible by protein templating, have long incubation periods, and…

Progeria (Hutchinson–Gilford progeria syndrome) Progeria Rare genetic disorder causing features of premature aging in children, caused by a mutation that produces abnormal lamin A (progerin); leads to growth failure and early cardiovascu…

Progeroid Syndromes: Causes, Features, and Research Significance Progeroid syndromes Progeroid syndromes are rare, usually monogenic conditions that produce features resembling accelerated aging. This article explains causes, typical signs, diagnosis, management, a…

Prognosis (medical prediction of disease outcome) Prognosis Prognosis is the anticipated course, likely outcome, and expected complications of a disease or condition. It informs treatment choices, patient counseling, and planning for care a…

Progressive muscular atrophy Progressive muscular atrophy (PMA) is a rare motor neuron disease affecting lower motor neurons that causes progressive muscle wasting and weakness. Diagnosis is clinical, supporte…

Prostate: anatomy, function, common conditions, diagnosis and treatment Prostate Comprehensive overview of the prostate gland: location, role in reproduction, common disorders (BPH, prostatitis, cancer), symptoms, screening, and treatment approaches.

Prostate cancer Prostate cancer is a malignancy of the prostate gland in men. Covers causes, symptoms, diagnosis, staging, treatments, genetic risks (including BRCA2), and screening considerations…

Prostatectomy Prostatectomy is surgical removal of part or all of the prostate gland. This article explains types, indications, techniques, risks, recovery, and alternatives in neutral, concise…

Prostatitis: causes, types, symptoms, diagnosis and management Prostatitis Prostatitis is inflammation of the male prostate gland that causes pain, urinary and sexual symptoms. This article reviews types, causes, diagnosis, treatment options and key disti…

Pseudoephedrine: clinical use, pharmacology, effects and regulatory issues Pseudoephedrine Concise encyclopedic overview of pseudoephedrine: uses as a decongestant, mechanism, formulations, adverse effects, interactions, considerations for special populations, and regula…