Internal Medicine — Find Specialists & Top Hospitals Worldwide | MyMedicPlus

Internal medicine is the medical specialty focused on the prevention, diagnosis, and treatment of diseases in adults. Physicians who specialise in internal medicine — called internists or general physicians — are trained to evaluate and manage complex, multi-system illnesses that extend beyond the scope of routine primary care. Unlike a general practitioner (GP) or family physician who treats patients of all ages, an internist focuses exclusively on adults and is equipped to handle the diagnostic intricacies of patients who have several overlapping chronic conditions simultaneously.

Internists are often described as 'the doctors' doctor,' meaning they frequently serve as the diagnostic hub when a patient's illness is undifferentiated or unusually complex. They coordinate care across other specialties including cardiology, nephrology, endocrinology, and rheumatology, and are integral to both outpatient and hospital-based medicine.

Hospitalists — internists who work exclusively in hospital settings — manage acutely unwell adult inpatients, overseeing complex medication regimens, coordinating specialist consultations, and planning safe hospital discharge. Most adult medicine subspecialties, including gastroenterology, pulmonology, and infectious disease, derive from internal medicine, making it the foundational specialty of adult healthcare.

Internists manage an exceptionally broad range of adult medical conditions, often caring for patients with multiple diagnoses at once. Common conditions they diagnose and treat include:

• Hypertension (high blood pressure): Chronic elevation in blood pressure requiring medication, lifestyle intervention, and regular monitoring to prevent cardiovascular and kidney damage.
• Type 2 diabetes mellitus: Metabolic disorder involving insulin resistance, managed with medications, diet, and glucose monitoring to prevent complications.
• Dyslipidaemia (high cholesterol): Abnormal blood lipid levels increasing risk of coronary artery disease, managed with statins and lifestyle changes.
• Coronary artery disease and heart failure: Chronic cardiac conditions requiring medication optimisation, risk factor control, and coordination with cardiology.
• Chronic obstructive pulmonary disease (COPD): Progressive airflow obstruction from smoking or occupational exposures, managed with inhalers and pulmonary rehabilitation.
• Chronic kidney disease (CKD): Progressive loss of kidney function requiring careful medication review, blood pressure control, and nephrology co-management.
• Autoimmune conditions: Including rheumatoid arthritis, lupus, and inflammatory bowel disease in their less complex presentations before subspecialty referral.
• Thyroid disorders: Hypothyroidism and hyperthyroidism diagnosed and managed with medication titration.
• Anaemia: Evaluation of underlying cause and appropriate treatment selection.
• Complex infections: Including pneumonia, sepsis, and urinary tract infections requiring hospital-level management.

While internists are non-surgical physicians, they are trained to perform a number of diagnostic and therapeutic bedside procedures that are essential to acute and chronic medical care:

• Thoracentesis: Draining fluid from the pleural space around the lungs using a needle, performed under ultrasound guidance to diagnose or relieve pleural effusions.
• Paracentesis: Removal of fluid from the abdominal cavity in patients with ascites due to liver disease or malignancy.
• Lumbar puncture (spinal tap): Sampling cerebrospinal fluid to diagnose meningitis, subarachnoid haemorrhage, or inflammatory neurological conditions.
• Joint aspiration (arthrocentesis): Withdrawing fluid from swollen joints to diagnose gout, infection, or inflammatory arthritis.
• Arterial blood gas sampling: Collecting arterial blood from the radial or femoral artery to assess oxygenation and acid-base status.
• Bone marrow biopsy: Sampling bone marrow tissue to diagnose blood disorders and haematological malignancies.
• Central venous catheter insertion: Placing lines for fluid resuscitation, medication delivery, and monitoring in critically unwell patients.
• Bedside echocardiography and ultrasound: Point-of-care imaging to assess cardiac function and guide procedures.

An internist is the appropriate specialist in several important clinical scenarios involving adults:

• Multiple chronic conditions: When a patient has three or more active medical problems — such as diabetes, hypertension, and chronic kidney disease — requiring coordinated medication management and regular monitoring.
• Diagnostic uncertainty: When initial workup by a GP has not yielded a clear diagnosis, particularly for unexplained weight loss, persistent fever, fatigue, or abnormal laboratory findings.
• Hospital admission for acute illness: Internists (hospitalists) lead the medical care of adults admitted with acute conditions such as pneumonia, heart failure exacerbation, diabetic ketoacidosis, acute kidney injury, or gastrointestinal bleeding.
• Complex medication management: When a patient is on multiple medications with potential interactions or requires medication reconciliation across specialties.
• Pre-operative medical clearance: Internists assess surgical fitness and optimise medical conditions before elective or semi-elective surgical procedures.
• Elevated risk markers: Unexplained anaemia, elevated inflammatory markers (CRP, ESR), persistently abnormal kidney or liver function tests, or new-onset hypertension requiring investigation.

Becoming an internist requires extensive medical education and supervised clinical training across all adult organ systems. The pathway in the United States begins with a four-year undergraduate medical degree (MD or DO), followed by a three-year residency in internal medicine at an accredited program, during which trainees rotate through hospital wards, intensive care, outpatient clinics, and subspecialty services.

Following residency, many internists pursue further subspecialty fellowship training lasting two to three years in fields such as cardiology, gastroenterology, nephrology, rheumatology, endocrinology, infectious disease, hematology-oncology, or pulmonary and critical care medicine. Fellows gain advanced diagnostic and procedural skills specific to their chosen subspecialty.

Board certification by the American Board of Internal Medicine (ABIM) is required for practice as an internist in the United States. Equivalent boards exist in other countries, including the Royal Colleges of Physicians in the UK, Canada, and Australia. Ongoing maintenance of certification (MOC) requires periodic recertification examinations and continuing medical education throughout a physician's career.

Internists typically see patients through referral from a primary care physician (GP or family doctor), or via hospital admission for acute illness. In many health systems, the internist serves as the primary attending physician for hospitalised adult patients, coordinating care from admission to discharge.

For outpatient care, ask your GP for a referral to an internal medicine specialist if you have multiple complex conditions or an unresolved diagnostic problem. At your first appointment, bring a complete list of current medications, recent laboratory results (within the past 6–12 months), prior imaging reports, and a summary of your medical history. Be prepared to describe all your current symptoms and how they affect your daily life. Internists typically conduct thorough consultations of 30–60 minutes to develop a comprehensive management plan.