Condition guides

Acne affects roughly 50 million people in the US each year, with breakouts ranging from blackheads and whiteheads to painful cysts.

Acute coronary syndrome is the umbrella term for heart attacks and unstable angina — when a coronary artery suddenly narrows or closes.

Acute coronary syndromes include heart attacks and unstable angina — sudden blockages in the arteries that feed the heart.

Acute kidney injury happens when the kidneys suddenly stop filtering waste from the blood, often during serious illness, surgery, or from certain medications.

Acute lymphoblastic leukemia is a cancer of white blood cells that progresses rapidly without treatment.

Acute myeloid leukemia is a blood cancer that starts in the bone marrow and moves quickly.

ADHD affects about 10% of children and 4% of adults in the U.S., making it one of the most common neurodevelopmental conditions.

Alcohol use disorder affects about 29 million American adults.

Alopecia areata causes the immune system to attack hair follicles, creating smooth, round patches of hair loss on the scalp or body.

ALS (amyotrophic lateral sclerosis) is a disease where nerve cells controlling voluntary movement gradually die.

Alzheimer's disease is the most common cause of dementia, affecting more than 6 million Americans.

Amyloidosis occurs when misfolded proteins clump in organs, disrupting normal function.

Amyotrophic lateral sclerosis is a progressive disease that kills motor neurons, the nerve cells that control voluntary muscles.

Anal cancer is diagnosed in about 9,000 people per year in the United States.

Anemia means your blood doesn't carry enough oxygen, usually because of low red blood cell count or low hemoglobin.

Ankylosing spondylitis is an inflammatory arthritis that primarily affects the spine and sacroiliac joints, causing pain and stiffness that's often worst in the morning.

Anorexia nervosa is a serious eating disorder where people severely restrict food intake, often to dangerous weights.

Anxiety disorders affect roughly 30% of adults at some point in life.

Anxiety disorders affect roughly one in five adults in the US.

An aortic aneurysm is a bulge in the wall of the aorta, the body's largest artery.

Aortic stenosis is a narrowing of the heart's aortic valve that blocks blood flow from the heart to the body.

Aplastic anemia is a rare bone marrow failure disorder where the body stops making enough blood cells.

Asthma affects more than 25 million Americans and ranges from mild, occasional symptoms to severe disease requiring daily controller medications.

Atherosclerosis is the buildup of fatty deposits in artery walls, narrowing blood vessels and raising the risk of heart attack and stroke.

Atopic dermatitis is a chronic skin condition marked by itchy, inflamed patches that flare and fade over time.

Atrial fibrillation is the most common heart rhythm disorder, affecting millions of people worldwide.

Autism spectrum disorder affects about 1 in 36 children in the United States.

Becker muscular dystrophy is a genetic disorder caused by mutations in the dystrophin gene, leading to progressive muscle weakness that typically begins in the legs and pelvis during childhood or adolescence.

Benign prostatic hyperplasia (BPH) is non-cancerous prostate enlargement that affects most men over 50.

Beta thalassemia is an inherited blood disorder where the body makes too little hemoglobin, causing anemia that ranges from mild to severe.

Binge eating disorder affects about 2-3% of adults in the US, making it the most common eating disorder.

Bipolar disorder affects about 2.8% of U.S.

Bladder cancer affects about 80,000 Americans each year, with most cases caught early when the tumor is confined to the bladder's inner lining.

Bone marrow transplantation, also called hematopoietic stem cell transplantation, replaces damaged or diseased bone marrow with healthy stem cells.

Borderline personality disorder affects about 1-2% of people and involves intense emotions, unstable relationships, and a fragile sense of self.

Breast cancer is the most common cancer in women worldwide.

Bronchiectasis is a lung condition where airways become permanently widened and scarred, making it hard to clear mucus.

Bulimia nervosa involves cycles of binge eating followed by behaviors to prevent weight gain, like vomiting or excessive exercise.

Cardiomyopathy describes several diseases where the heart muscle weakens, stiffens, or thickens, making it harder to pump blood.

Cardiovascular disease remains the leading cause of death worldwide, but treatment has advanced dramatically.

Cardiovascular diseases include heart attack, stroke, heart failure, and conditions like atrial fibrillation.

Carpal tunnel syndrome happens when pressure on the median nerve in the wrist causes numbness, tingling, and pain in the hand.

Cataracts are clouding of the eye's natural lens, affecting more than half of Americans over 80.

Cataracts are clouding of the eye's lens that develops with age in most people over 60.

Celiac disease is an autoimmune condition where eating gluten damages the small intestine.

Cerebral palsy is a group of movement and posture disorders caused by brain injury before, during, or shortly after birth.

Cervical cancer is largely preventable through HPV vaccination and screening, yet it remains a leading cause of cancer death worldwide.

Charcot-Marie-Tooth disease is a group of inherited nerve disorders affecting about 1 in 2,500 people.

Cholangiocarcinoma is a rare cancer of the bile ducts, the tubes that carry digestive fluid from the liver.

Chronic kidney disease affects about 37 million Americans, most from diabetes or high blood pressure.

Chronic low back pain affects roughly one in five adults and is a leading cause of disability worldwide.

Chronic lymphocytic leukemia is a slow-growing blood cancer affecting white blood cells called lymphocytes.

Chronic myeloid leukemia is a blood cancer driven by a gene mutation that produces an abnormal protein called BCR-ABL.

Chronic pain affects roughly 50 million American adults and has few curative treatments.

Cleft palate is a birth defect where the roof of the mouth doesn't fully close during fetal development, affecting about 1 in 1,600 babies.

Colorectal cancer is the third most common cancer in the United States, affecting about 150,000 people each year.

Concussion is a mild traumatic brain injury that temporarily disrupts normal brain function.

Chronic obstructive pulmonary disease (COPD) is a lung condition that makes breathing progressively harder, usually from smoking or air pollution damage.

Coronary artery disease affects more than 18 million Americans.

COVID-19 is caused by the SARS-CoV-2 virus and triggered a global pandemic beginning in 2020.

Crohn's disease is a chronic inflammatory bowel disease affecting about 500,000 Americans.

Cystic fibrosis is a genetic disease that causes thick mucus to build up in the lungs and other organs, leading to infections and digestive problems.

Deep vein thrombosis is a blood clot that forms in a deep vein, usually in the leg.

Dementia describes a decline in memory, thinking, and daily function caused by diseases like Alzheimer's, vascular dementia, Lewy body dementia, and frontotemporal dementia.

Depression is one of the most common mental health conditions, affecting roughly one in six adults at some point in life.

Dermatomyositis causes muscle weakness and a distinctive skin rash, often appearing on the face, knuckles, and upper body.

Diabetes affects over 37 million Americans and occurs when the body can't properly regulate blood sugar.

Diabetic neuropathy affects about half of all people with diabetes over time, causing numbness, pain, or weakness in the feet and hands.

Diabetic retinopathy damages the blood vessels in the retina and is the leading cause of vision loss in working-age adults.

Diffuse large B-cell lymphoma is the most common type of non-Hodgkin lymphoma, making up about one-third of cases.

Dilated cardiomyopathy means the heart's main pumping chamber stretches and weakens, making it harder to pump blood.

Down syndrome occurs when a person is born with an extra copy of chromosome 21.

Dry eye disease affects roughly 16 million Americans, causing discomfort, blurred vision, and in severe cases damage to the cornea.

Duchenne muscular dystrophy is a genetic disease that causes progressive muscle weakness, usually diagnosed in boys around age 3-5.

Dystonia causes involuntary muscle contractions that twist the body into abnormal postures or repetitive movements.

Eczema, or atopic dermatitis, affects roughly 10% of adults and 25% of children in the US.

Endometrial cancer is the most common gynecologic cancer in the United States, with about 66,000 new cases each year.

Endometriosis occurs when tissue similar to the uterine lining grows outside the uterus, causing pain, inflammation, and sometimes infertility.

Eosinophilic esophagitis is a chronic immune condition where white blood cells called eosinophils build up in the esophagus, causing inflammation, difficulty swallowing, and food getting stuck.

Epilepsy affects about 3.4 million people in the U.S., causing recurrent seizures that vary widely in type and severity.

Erectile dysfunction affects about 30 million men in the U.S.

Esophageal cancer is the sixth most common cause of cancer death worldwide, with about 20,000 new cases diagnosed in the U.S.

Essential tremor is the most common movement disorder, affecting about 10 million people in the United States.

Ewing sarcoma is a rare bone and soft tissue cancer that mostly affects children and young adults.

Fabry disease is a rare inherited disorder in which the body can't break down a certain type of fat, causing it to build up in organs and blood vessels.

Fallopian tube cancer is rare, accounting for about 1% of gynecologic cancers.

Fibromyalgia causes widespread pain, fatigue, and often sleep problems and brain fog.

Follicular lymphoma is a slow-growing blood cancer that starts in white blood cells called B cells.

Gastric cancer, or stomach cancer, affects roughly 26,000 people in the United States each year.

Gastroesophageal reflux disease (GERD) affects roughly 20% of adults in the U.S., causing heartburn when stomach acid flows back into the esophagus.

Gastroparesis means the stomach empties too slowly, causing nausea, vomiting, bloating, and unpredictable blood sugar in people with diabetes.

Gestational diabetes develops during pregnancy when hormones make it harder for the body to use insulin.

Giant cell arteritis is an inflammation of medium and large arteries, most often affecting people over 50.

Glaucoma damages the optic nerve, usually from high pressure inside the eye, and is a leading cause of blindness.

Glioblastoma is the most aggressive brain tumor, with median survival around 15 months despite surgery, radiation, and chemotherapy with temozolomide.

Gliomas are brain tumors that arise from glial cells, the support cells surrounding neurons.

Glomerulonephritis is inflammation of the kidney's filtering units, which can be triggered by infections, autoimmune disease, or other causes.

Graft-versus-host disease occurs when donor immune cells attack a transplant recipient's tissues, most often after stem cell or bone marrow transplant.

Graves' disease is the most common cause of hyperthyroidism in the United States, affecting about 1 in 200 people.

Head and neck cancers include tumors of the mouth, throat, voice box, sinuses, and salivary glands.

Around 48 million Americans have some degree of hearing loss, caused by aging, noise exposure, genetics, infections, or medications.

Heart disease remains the leading cause of death in the United States, affecting more than 120 million adults.

Heart failure affects more than 6 million Americans and happens when the heart can't pump blood efficiently enough to meet the body's needs.

Hemophilia A is a bleeding disorder caused by low or missing factor VIII, a clotting protein.

Hemophilia B is a bleeding disorder caused by missing or low levels of clotting factor IX.

Hepatitis B affects roughly 300 million people worldwide.

Hepatitis C is a viral infection that damages the liver.

Hepatocellular carcinoma is the most common type of liver cancer, often developing in people with chronic hepatitis B, hepatitis C, or cirrhosis from any cause.

Hidradenitis suppurativa causes painful lumps, abscesses, and tunnels under the skin, usually in areas where skin rubs together.

HIV treatment has advanced dramatically since the 1980s.

Hodgkin lymphoma is a cancer of the lymphatic system that affects about 8,000 people in the US each year.

Human papillomavirus infection is extremely common — most sexually active people get it at some point.

Huntington's disease is a fatal inherited brain disorder caused by a single genetic mutation.

Hydrocephalus occurs when cerebrospinal fluid builds up in the brain's ventricles, causing pressure that can damage brain tissue.

Hypercholesterolemia means having too much cholesterol in the blood, which increases the risk of heart attack and stroke.

Hypertension affects about one in three adults in the United States.

Hyperthyroidism happens when the thyroid gland produces too much thyroid hormone, causing symptoms like rapid heartbeat, weight loss, anxiety, and heat intolerance.

Hypertrophic cardiomyopathy (HCM) is a genetic heart condition where the heart muscle becomes abnormally thick, making it harder for the heart to pump blood.

Hypothyroidism means the thyroid gland doesn't make enough thyroid hormone.

Idiopathic pulmonary fibrosis causes scarring in the lungs that gradually makes breathing harder.

IgA nephropathy is the most common form of glomerulonephritis worldwide, caused by deposits of IgA antibodies damaging the kidney's filtering units.

Infertility affects about one in six couples trying to conceive.

Influenza causes seasonal epidemics that sicken millions each year and occasional pandemics when new strains emerge.

Insomnia affects about one-third of adults at some point, with roughly 10% experiencing chronic sleep difficulty.

Iron deficiency anemia occurs when the body lacks enough iron to make hemoglobin, the protein in red blood cells that carries oxygen.

Irritable bowel syndrome affects about 10-15% of adults worldwide, causing abdominal pain, bloating, diarrhea, and constipation without visible damage to the gut.

Ischemic stroke happens when a blood clot blocks flow to part of the brain.

Kidney cancer includes several types, most commonly renal cell carcinoma.

Knee osteoarthritis affects more than 14 million Americans, causing pain and stiffness as cartilage wears down.

Leukemia is a cancer of the blood and bone marrow, diagnosed in about 60,000 Americans each year.

Lipoprotein(a), or Lp(a), is a cholesterol particle that raises heart attack and stroke risk regardless of LDL levels.

Liver cancer is the third-leading cause of cancer death worldwide, with most cases arising in people who have cirrhosis from hepatitis B, hepatitis C, or fatty liver disease.

Liver cirrhosis is scarring of the liver caused by long-term damage from hepatitis, alcohol, fatty liver disease, or other conditions.

Long COVID affects an estimated 10-30% of people who had COVID-19, causing fatigue, brain fog, shortness of breath, and dozens of other symptoms that persist for months or years.

Low back pain affects most adults at some point, and for many it becomes chronic.

Lung cancer is the leading cause of cancer death worldwide, but treatment has changed dramatically in the past decade.

Lupus is an autoimmune disease that causes the immune system to attack healthy tissue throughout the body, affecting joints, skin, kidneys, blood cells, brain, heart, and lungs.

Lupus nephritis is kidney inflammation caused by systemic lupus erythematosus, affecting roughly half of people with lupus.

Lymphoma is cancer of the lymphatic system, divided into Hodgkin and non-Hodgkin types with dozens of subtypes.

Age-related macular degeneration is the leading cause of vision loss in people over 50, affecting the central part of the retina needed for reading and recognizing faces.

Major depressive disorder affects about 8% of U.S.

Malaria kills roughly 600,000 people each year, mostly children in sub-Saharan Africa.

Mantle cell lymphoma is a rare, aggressive B-cell lymphoma that typically affects people in their sixties.

Marfan syndrome is a genetic connective tissue disorder affecting about 1 in 5,000 people.

Melanoma is the most serious type of skin cancer, arising from pigment-producing cells.

Meningiomas are tumors that grow from the membranes covering the brain and spinal cord.

Menopause is the permanent end of menstrual periods, typically occurring between ages 45 and 55.

Mesothelioma is a cancer of the lining around the lungs, heart, or abdomen, caused almost always by asbestos exposure decades earlier.

Metabolic syndrome is a cluster of conditions — high blood pressure, high blood sugar, excess belly fat, and abnormal cholesterol — that together raise the risk of heart disease, stroke, and type 2 diabetes.

Migraine affects about 1 in 7 people worldwide and is the second-leading cause of disability globally.

Mild cognitive impairment (MCI) describes noticeable changes in memory or thinking that don't yet interfere much with daily life.

Multiple myeloma is a blood cancer affecting plasma cells in the bone marrow.

Multiple sclerosis affects about 1 million people in the United States.

Muscular dystrophy refers to more than 30 genetic conditions that cause progressive muscle weakness.

Myasthenia gravis is an autoimmune disease where the immune system attacks the connections between nerves and muscles, causing weakness that worsens with activity.

Myelodysplastic syndromes are a group of bone marrow disorders where blood cells don't develop properly, leading to low counts and a risk of progression to acute leukemia.

A heart attack happens when a blocked artery cuts off blood to part of the heart muscle, causing tissue damage.

Myopia, or nearsightedness, affects nearly half of young adults in some countries and is becoming more common worldwide.

Myositis refers to a group of rare autoimmune diseases that cause chronic muscle inflammation and weakness.

Neuroblastoma is a cancer of immature nerve cells that mostly affects children under five.

Neurofibromatosis refers to three genetic conditions — NF1, NF2, and schwannomatosis — that cause tumors to grow on nerves throughout the body.

Non-alcoholic fatty liver disease affects roughly one in four adults worldwide.

Non-alcoholic steatohepatitis, or NASH, is liver inflammation and damage caused by fat buildup in people who drink little or no alcohol.

Non-Hodgkin lymphoma includes more than 60 distinct cancers that start in the lymph system.

Non-small cell lung cancer accounts for about 85% of all lung cancers.

Obesity affects more than 40% of adults in the United States and contributes to diabetes, heart disease, joint problems, and certain cancers.

Obstructive sleep apnea affects roughly 30 million adults in the US, causing repeated pauses in breathing during sleep.

Obsessive-compulsive disorder affects about 1 in 40 adults in the U.S.

Opioid use disorder affects millions of Americans and can involve prescription painkillers, heroin, or fentanyl.

Osteoarthritis affects more than 30 million U.S.

Knee osteoarthritis affects more than 14 million adults in the US, making it one of the most common causes of chronic pain and disability.

Osteoporosis weakens bones to the point where they fracture easily, often in the spine, hip, or wrist.

Osteosarcoma is a rare bone cancer that most often affects teenagers and young adults, typically forming near the growth plates in the arm or leg.

Ovarian cancer is often diagnosed at advanced stages because early symptoms are vague and no reliable screening test exists.

Pancreatic cancer is often found late, when it has already spread beyond the pancreas.

Pancreatitis is inflammation of the pancreas, occurring either suddenly (acute) or as ongoing damage (chronic).

Parkinson's disease affects around one million Americans, causing tremor, stiffness, and slow movement as dopamine-producing brain cells die off.

Periodontitis is gum disease that destroys the bone and tissue supporting teeth, affecting nearly half of adults over 30 in some form.

Peripheral artery disease narrows arteries in the legs, causing pain with walking and raising the risk of amputation and heart attack.

Polycystic kidney disease causes fluid-filled cysts to grow in the kidneys, eventually damaging tissue and reducing function.

Polycystic ovary syndrome affects about one in ten women of reproductive age, causing irregular periods, elevated androgen hormones, and often insulin resistance.

Polymyalgia rheumatica causes pain and stiffness in the shoulders, neck, and hips, typically in people over 50.

Postpartum depression affects about one in seven women after childbirth, causing persistent sadness, anxiety, and difficulty bonding with the baby.

Pre-eclampsia is high blood pressure that develops during pregnancy, usually after 20 weeks, often with protein in the urine or signs of organ stress.

Primary biliary cholangitis is a chronic liver disease where the immune system attacks the bile ducts.

Prostate cancer is the most common cancer in men in the United States, with about one in eight men diagnosed during their lifetime.

Psoriasis affects about 8 million Americans, causing skin cells to build up into red, scaly patches that can itch, crack, and bleed.

Psoriatic arthritis affects about 30% of people with psoriasis, causing joint pain, stiffness, and sometimes permanent damage if untreated.

Post-traumatic stress disorder affects about 6% of Americans at some point in life, with symptoms like intrusive memories, hypervigilance, and avoidance that persist long after trauma exposure.

Pulmonary arterial hypertension is a rare disease where blood pressure in the lung arteries rises dangerously high, straining the heart's right side.

Pulmonary embolism occurs when a blood clot blocks an artery in the lungs, typically traveling from a deep vein in the leg.

Pulmonary fibrosis causes scarring in the lungs that makes breathing progressively harder.

Pulmonary hypertension is high blood pressure in the arteries to the lungs.

Rectal cancer treatment typically involves surgery, often combined with radiation and chemotherapy.

Renal cell carcinoma accounts for about 90% of kidney cancers.

Retinitis pigmentosa is a group of inherited eye diseases that damage the light-sensing cells in the retina.

Rheumatoid arthritis is an autoimmune disease that causes joint inflammation, pain, and damage, affecting about 1 in 100 adults.

Sarcoidosis causes clusters of inflammatory cells called granulomas to form in organs, most often the lungs and lymph nodes.

Sarcomas are rare cancers arising from bone, muscle, fat, blood vessels, or other connective tissues.

Sarcopenia is the loss of muscle mass and strength that happens with aging, affecting about 10% of adults over 60.

Schizophrenia affects about 1 in 100 people worldwide, causing hallucinations, delusions, and difficulties with thinking and motivation.

Scleroderma is a rare autoimmune disease where the immune system triggers excessive collagen production, hardening the skin and sometimes internal organs.

Sepsis happens when the body's response to infection spirals out of control, damaging organs and sometimes leading to death.

Sickle cell disease is an inherited blood disorder affecting about 100,000 Americans, mostly of African descent.

Soft tissue sarcomas are a rare group of cancers arising in muscles, fat, blood vessels, and connective tissues throughout the body.

Spinal cord injuries affect about 17,000 people in the United States each year, mostly from vehicle crashes, falls, or sports injuries.

Spinal cord injury affects around 300,000 people in the United States, with roughly 18,000 new injuries each year.

Spinal muscular atrophy is a genetic disease that weakens muscles throughout the body.

Squamous cell carcinoma is the second most common skin cancer, affecting more than one million Americans each year.

Stroke happens when blood flow to part of the brain is blocked or a blood vessel bursts, killing brain cells.

Substance use disorder affects more than 40 million Americans.

Systemic sclerosis causes the immune system to attack connective tissue, leading to skin thickening and damage to internal organs—especially the lungs, heart, and digestive system.

Testicular cancer is one of the most curable cancers, with cure rates above 95% even when it has spread.

Thrombocytopenia means having too few platelets, the blood cells that stop bleeding.

Thyroid cancer is the most common endocrine cancer, with about 44,000 new cases yearly in the US.

Tinnitus — ringing, buzzing, or other phantom sounds in the ears — affects roughly 10-15% of adults.

Traumatic brain injury affects roughly 2.8 million Americans each year, ranging from concussions to severe injuries that cause lasting disability.

Tuberculosis is a bacterial infection that mainly affects the lungs but can spread to other organs.

Type 1 diabetes is an autoimmune disease where the body destroys insulin-producing beta cells in the pancreas.

Type 2 diabetes affects more than 500 million people worldwide.

Ulcerative colitis causes ongoing inflammation and ulcers in the colon, leading to bleeding, diarrhea, and abdominal pain.

Urinary incontinence affects roughly half of women over 65 and millions of men, especially after prostate surgery.

Uterine fibroids are noncancerous growths in the uterus that affect up to 80% of women by age 50.

Uveitis is inflammation inside the eye that can blur vision, cause pain, and lead to permanent damage if untreated.

Vasculitis describes a group of rare diseases that inflame blood vessels, damaging organs from the kidneys to the lungs to the skin.

Vitiligo causes patches of skin to lose pigment, leaving white or light-colored areas that can appear anywhere on the body.

Vulvar cancer makes up about 6% of gynecologic cancers in the United States, with roughly 6,000 new cases each year.

Wet age-related macular degeneration happens when abnormal blood vessels grow under the retina and leak fluid, blurring central vision.

Wilms tumor is a kidney cancer that mostly affects children under age 5.