Harrison’s Principles of Internal Medicine is the world's most trusted clinical medicine text―and a superb resource for learning the art and science of clinical reasoning. Recognized by healthcare professionals worldwide as the leading authority on applied pathophysiology and clinical medicine, Harrison’s Principles of Internal Medicine provides the informational foundation you need for the best patient care possible. This new edition is fully updated with timely new chapters and essential updates across the spectrum of internal medicine. 

Written and edited by the world’s top experts in their respective fields, this landmark guide provides comprehensive, accurate, and essential coverage of the pathogenesis, diagnosis, and treatment of disease. 

Harrison’s is world-renowned as the most authoritative source for: 

• Clear, concise schemas that facilitate the generation of differential diagnoses to reason efficiently through complex real world clinical cases
• The physiologic and epidemiologic basis of signs and symptoms, which are covered through a wealth of unsurpassed expert guidance and linked to the disease-specific chapters that follow
• Updated clinical trial results and recommended guidelines
• Excellent and extensive visual support, including radiographs, clinical photos, schematics, and high-quality drawings
• Coverage of both therapeutic approaches and specific treatment regimens
• Practical clinical decision trees and algorithms
• Organ/system-specific sections, with clinically relevant pathophysiology and practical clinical advice on the approach to the patient, strategies towards building a differential diagnosis, outstanding clinical algorithms and diagnostic schema, a wealth of clinical images and diagrams, current clinical guidelines, and general and specific approaches to therapy

Harrison’s remains the most trusted resource in a world influenced by endless sources of medical information. The most timely and comprehensive updates from the world’s top experts are featured in the 21st edition: 

• Current coverage of the diagnosis and treatment of diseases, from COVID to dementia to sepsis to multiple sclerosis to lung cancer
• Updated content that reflects new approved therapeutics and new practice-changing guidelines and evidence summaries
• More than 1000 clinical, pathological, and radiographic photographs, diagnostic and therapeutic decision trees, and clear schematics and diagrams describing pathophysiologic processes
• Numerous atlases featuring curated collections of important visual aspects of diagnosis and management
• Updated and time-saving curation and synthesis of established and new medical literature and studies
• Clinically relevant coverage of disease mechanics and pathophysiology, and related therapeutic mechanisms

Part 1: The Profession of Medicine
Updated! Chapter 1: The Practice of Medicine
Updated! Chapter 2: Promoting Good Health
Updated! Chapter 3: Vaccine Opposition and Hesitancy
Updated! Chapter 4: Decision-Making in Clinical Medicine
Updated! Chapter 5: Precision Medicine and Clinical Care
New! Chapter 6: Screening and Prevention of Disease
Updated! Chapter 7: Global Diversity of Health System Financing and Delivery
Updated! Chapter 8: The Safety and Quality of Health Care
Updated! Chapter 9: Diagnosis: Reducing Errors and Improving Quality
New! Chapter 10: Racial and Ethnic Disparities in Health Care
Updated! Chapter 11: Ethical Issues in Clinical Medicine
New! Chapter 12: Palliative and End-of-Life Care
Part 2: Cardinal Manifestations and Presentation of Diseases
Section 1: Pain
New! Chapter 13: Pain: Pathophysiology and Management
New! Chapter 14: Chest Discomfort
New! Chapter 15: Abdominal Pain
New! Chapter 16: Headache
New! Chapter 17: Back and Neck Pain
Section 2: Fever
New! Chapter 18: Fever
New! Chapter 19: Fever and Rash
New! Chapter 20: Fever of Unknown Origin
Section 3: Nervous System Dysfunction
New! Chapter 21: Syncope
Updated! Chapter 22: Dizziness and Vertigo
New! Chapter 23: Fatigue
New! Chapter 24: Neurologic Causes of Weakness and Paralysis
New! Chapter 25: Numbness, Tingling, and Sensory Loss
New! Chapter 26: Gait Disorders, Imbalance, and Falls
Updated! Chapter 27: Confusion and Delirium
New! Chapter 28: Coma
New! Chapter 29: Dementia
New! Chapter 30: Aphasia, Memory Loss, and Other Cognitive Disorders
New! Chapter 31: Sleep Disorders
Section 4: Disorders of Eyes, Ears, Nose, and Throat
New! Chapter 32: Disorders of the Eye
New! Chapter 33: Disorders of Smell and Taste
New! Chapter 34: Disorders of Hearing
New! Chapter 35: Upper Respiratory Symptoms, Including Earache, Sinus Symptoms, and Sore Throat
New! Chapter 36: Oral Manifestations of Disease
Section 5: Alterations in Circulatory and Respiratory Functions
New! Chapter 37: Dyspnea
New! Chapter 39: Hemoptysis
New! Chapter 38: Cough
New! Chapter 40: Hypoxia and Cyanosis
New! Chapter 41: Edema
New! Chapter 43: Palpitations
Section 6: Alterations in Gastrointestinal Function
New! Chapter 44: Dysphagia
New! Chapter 45: Nausea, Vomiting, and Indigestion
New! Chapter 46: Diarrhea and Constipation
New! Chapter 47: Unintentional Weight Loss
Updated! Chapter 48: Gastrointestinal Bleeding
New! Chapter 49: Jaundice
Updated! Chapter 50: Abdominal Swelling and Ascites
Section 7: Alterations in Renal and Urinary Tract Function
New! Chapter 51: Interstitial Cystitis/Bladder Pain Syndrome
New! Chapter 52: Azotemia and Urinary Abnormalities
New! Chapter 54: Hypercalcemia and Hypocalcemia
New! Chapter 55: Acidosis and Alkalosis
Section 8: Alterations in the Skin
New! Chapter 56: Approach to the Patient with a Skin Disorder
New! Chapter 57: Eczema, Psoriasis, Cutaneous Infections, Acne, and Other Common Skin Disorders
New! Chapter 58: Skin Manifestations of Internal Disease
New! Chapter 59: Immunologically Mediated Skin Diseases
New! Chapter 60: Cutaneous Drug Reactions
New! Chapter 61: Photosensitivity and Other Reactions to Sunlight
Section 9: Hematologic Alterations
New! Chapter 62: Interpreting Peripheral Blood Smears
New! Chapter 63: Anemia and Polycythemia
New! Chapter 64: Disorders of Granulocytes and Monocytes
New! Chapter 65: Bleeding and Thrombosis
New! Chapter 66: Enlargement of Lymph Nodes and Spleen
Part 3: Pharmacology
New! Chapter 67: Principles of Clinical Pharmacology
Updated! Chapter 68: Pharmacogenomics
Part 4: Oncology and Hematology
Section 1: Neoplastic Disorders
New! Chapter 70: Prevention and Early Detection of Cancer
New! Chapter 71: Cancer Genetics
New! Chapter 72: Cancer Cell Biology
New! Chapter 73: Principles of Cancer Treatment
New! Chapter 75: Oncologic Emergencies
New! Chapter 76: Cancer of the Skin
New! Chapter 77: Head and Neck Cancer
New! Chapter 80: Upper Gastrointestinal Tract Cancers
New! Chapter 81: Lower Gastrointestinal Cancers
New! Chapter 82: Tumors of the Liver and Biliary Tree
New! Chapter 85: Renal Cell Carcinoma
New! Chapter 86: Cancer of the Bladder and Urinary Tract
New! Chapter 87: Benign and Malignant Diseases of the Prostate
New! Chapter 88: Testicular Cancer
New! Chapter 89: Gynecologic Malignancies
New! Chapter 90: Primary and Metastatic Tumors of the Nervous System
New! Chapter 91: Soft Tissue and Bone Sarcomas and Bone Metastases
New! Chapter 93: Paraneoplastic Syndromes: Endocrinologic/Hematologic
New! Chapter 95: Cancer Survivorship and the Long-Term Impact of Cancer and Its Treatment
Section 2: Hematopoietic Disorders
New! Chapter 96: Hematopoietic Stem Cells
New! Chapter 97: Iron Deficiency and Other Hypoproliferative Anemias
New! Chapter 99: Megaloblastic Anemias
New! Chapter 101: Anemia Due to Acute Blood Loss
New! Chapter 102: Bone Marrow Failure Syndromes Including Aplastic Anemia and Myelodysplasia
New! Chapter 103: Polycythemia Vera and Other Myeloproliferative Neoplasms
New! Chapter 105: Chronic Myeloid Leukemia
New! Chapter 108: Non-Hodgkin’s Lymphoma
New! Chapter 109: Hodgkin’s Lymphoma
New! Chapter 112: Amyloidosis
New! Chapter 113: Transfusion Therapy and Biology
New! Chapter 114: Hematopoietic Cell Transplantation
Section 3: Disorders of Hemostasis
New! Chapter 115: Disorders of Platelets and Vessel Wall
New! Chapter 118: Antiplatelet, Anticoagulant, and Fibrinolytic Drugs
Part 5: Infectious Diseases
Section 2: Clinical Syndromes: Community-Acquired Infections
New! Chapter 126: Pneumonia
New! Chapter 138: Acute Meningitis
New! Chapter 139: Chronic and Recurrent Meningitis
New! Chapter 140: Brain Abscess and Empyema
New! Chapter 141: Infectious Complications of Bites
Section 3: Clinical Syndromes: Health Care-Associated Infections
New! Chapter 142: Infections Acquired in Health Care Facilities
New! Chapter 143: Infections in Transplant Recipients
Section 4: Therapy for Bacterial Diseases
New! Chapter 144: Treatment and Prophylaxis of Bacterial Infections
New! Chapter 145: Bacterial Resistance to Antimicrobial Agents
Section 5: Diseases Caused by Gram-Positive Bacteria
New! Chapter 146: Pneumococcal Infections
New! Chapter 147: Staphylococcal Infections
New! Chapter 148: Streptococcal Infections
New! Chapter 149: Enterococcal Infections
New! Chapter 150: Diphtheria and Other Corynebacterial Infections
New! Chapter 151: Listeria monocytogenes Infections
New! Chapter 152: Tetanus
New! Chapter 153: Botulism
New! Chapter 154: Gas Gangrene and Other Clostridial Infections
Section 6: Diseases Caused by Gram-Negative Bacteria
New! Chapter 155: Meningococcal Infections
New! Chapter 157: Haemophilus and Moraxella Infections
New! Chapter 158: Infections Due to the HACEK Group and Miscellaneous Gram-Negative Bacteria
New! Chapter 159: Legionella Infections
New! Chapter 160: Pertussis and Other Bordetella Infections
New! Chapter 161: Diseases Caused by Gram-Negative Enteric Bacilli
New! Chapter 162: Acinetobacter Infections
Part 7: Disorders of the Respiratory System
Section 1: Diagnosis of Respiratory Disorders
New! Chapter 284: Approach to the Patient with Disease of the Respiratory System
New! Chapter 285: Disturbances of Respiratory Function
Section 2: Diseases of the Respiratory System
New! Chapter 288: Hypersensitivity Pneumonitis and Pulmonary Infiltrates with Eosinophilia
Part 9: Disorders of the Kidney and Urinary Tract
New! Chapter 309: Cell Biology and Physiology of the Kidney
New! Chapter 312: Dialysis in the Treatment of Kidney Failure
New! Chapter 314: Glomerular Diseases
New! Chapter 315: Polycystic Kidney Disease and Other Inherited Disorders of Tubule Growth and Development
New! Chapter 317: Vascular Injury to the Kidney
New! Chapter 318: Nephrolithiasis
New! Chapter 319: Urinary Tract Obstruction
New! Chapter 320: Interventional Nephrology
Part 11: Immune-Mediated, Inflammatory, and Rheumatologic Disorders
Section 2: Disorders of Immune-Mediated Injury
New! Chapter 353: Anaphylaxis
New! Chapter 354: Mastocytosis
New! Chapter 357: Antiphospholipid Syndrome
New! Chapter 361: Sjögren’s Syndrome
New! Chapter 364: Behçet Syndrome
Part 12: Endocrinology and Metabolism
Section 1: Endocrinology
New! Chapter 383: Hypothyroidism
Part 13: Neurologic Disorders
Section 2: Diseases of the Central Nervous System
New! Chapter 431: Alzheimer’s Disease