Advanced systemic mastocytosis is a rare and serious blood disorder where abnormal mast cells build up uncontrollably in various organs, potentially causing organ damage and life-threatening complications.

Affective disorders are a group of mental health conditions characterized by significant disruptions in mood, ranging from severe depression to extreme elation, that can profoundly impact a person’s ability to function in daily life.

Age-related macular degeneration is a leading cause of vision loss in older adults, affecting nearly 20 million Americans. While it can blur your central vision and make everyday tasks more challenging, it doesn’t cause complete blindness, and treatments are available to help protect your sight.

Agitation is a state of severe restlessness or inner tension that can affect anyone, from brief episodes during stressful moments to persistent symptoms that signal an underlying medical condition.

Postoperative agitation is an abnormal mental state that develops after surgery, affecting up to half of older adults and occurring when patients wake from anesthesia feeling confused, restless, or unusually aggressive.

Aicardi-Goutières syndrome is a rare inherited disease that primarily attacks the brain’s white matter, triggering an immune system response that mistakenly turns against the body itself, leading to serious neurological problems that can appear at birth or develop within the first months of life.

Alagille syndrome is a genetic condition affecting multiple organs, most notably causing malformed or too few bile ducts in the liver, leading to bile buildup that damages liver tissue. This rare disorder can also affect the heart, eyes, bones, kidneys, and blood vessels, with symptoms ranging from mild to life-threatening.

Albright’s disease, medically known as McCune-Albright syndrome, is a rare genetic condition that affects bones, skin, and the hormonal system, causing a unique combination of symptoms that vary widely from person to person.

Albuminuria is a sign of kidney disease that occurs when too much albumin, a protein normally found in your blood, appears in your urine. This condition can serve as an important warning sign for kidney damage and related health problems.

Alcohol abuse, now commonly referred to as alcohol use disorder, is a medical condition affecting millions of people worldwide. It involves an impaired ability to control drinking despite serious consequences to health, relationships, and daily life. Understanding this condition as a treatable brain disorder, rather than a personal failing, is the first step toward recovery.

Alcohol use disorder is a medical condition that affects millions of people, making it difficult or impossible to control drinking even when it causes serious harm to health, relationships, and daily life. The good news is that treatment works, and most people can reduce their drinking or stop entirely with the right support.

Alcoholic liver disease develops after years of heavy drinking and can progress through several stages, from fatty liver to life-threatening cirrhosis. While early stages may cause no symptoms, the condition is one of the most common causes of chronic liver disease and can be reversed or slowed by stopping alcohol use.

Alcohol use disorder is a medical condition that affects millions of people worldwide, making it difficult to control drinking despite serious harm to health, relationships, and daily life. The good news is that effective treatments exist, and most people with this condition can reduce their drinking or stop entirely with the right support.

Alexander disease is a rare genetic disorder that progressively damages the nervous system, causing the protective coating around nerve fibers in the brain to deteriorate over time and leading to serious neurological problems.

Allergic respiratory disease occurs when your immune system overreacts to substances you breathe in, like pollen or pet dander, causing symptoms that affect your nose, throat, and lungs. Understanding what triggers your symptoms and how to manage them can help you breathe easier and improve your quality of life.

Allogeneic stem cell transplantation is a medical procedure that uses healthy stem cells from a donor to replace damaged or diseased bone marrow, offering hope for patients with blood cancers, blood disorders, and immune system conditions.

Alopecia areata is an autoimmune disease that causes your immune system to attack your hair follicles, leading to patchy hair loss on the scalp, face, or body—affecting nearly 7 million people in the United States.

Alpha-1 antitrypsin deficiency is a genetic condition that can lead to serious lung and liver damage. While there is no cure, understanding the condition and taking the right steps can help people with Alpha-1 manage their symptoms and maintain a good quality of life.

Alport’s syndrome is a rare genetic condition that affects the kidneys, ears, and eyes. It occurs when the body cannot produce normal proteins needed for healthy kidney function, which can lead to kidney failure over time.

An altered state of consciousness is any condition in which your mind works significantly differently from your normal waking state. These changes can affect how you perceive reality, your emotions, and even physical sensations, and they can occur naturally or be triggered by various factors.

Alternating hemiplegia of childhood is a rare brain disorder that causes sudden, temporary paralysis in young children, along with developmental challenges and other symptoms that can significantly impact their quality of life.

Alveolar bone defects are gaps or loss in the bone that holds and supports your teeth, which can result from various causes including gum disease, tooth loss, birth defects, or trauma, and often require specialized treatment to restore the bone and prevent further dental complications.

Alveolar proteinosis is a rare lung disease where proteins, fats, and other substances build up inside the tiny air sacs of the lungs, making it hard to breathe and blocking oxygen from reaching the blood.

Alveolar rhabdomyosarcoma is a rare and aggressive form of soft tissue cancer that typically strikes teenagers and young adults. This cancer develops from skeletal muscle cells and often appears in the arms, legs, or trunk, spreading rapidly and presenting unique treatment challenges.

Amnestic disorder, also called amnesia or amnestic syndrome, involves significant loss of memories that goes far beyond everyday forgetfulness—it can affect your ability to remember important events from your past or make it difficult to form and retain new memories.

Amyloidosis is a rare disease that occurs when abnormal proteins called amyloid build up in your body’s organs and tissues, affecting how they work. While the disease can be serious, new treatments and better understanding mean that many people can manage their condition and live fulfilling lives.

Amyotrophic lateral sclerosis is a progressive nervous system disease that affects nerve cells in the brain and spinal cord, leading to loss of muscle control. While there is currently no cure, treatments and supportive care can help manage symptoms and improve quality of life.

Anaemia occurs when your body doesn’t have enough healthy red blood cells to carry oxygen throughout your body, leaving you feeling tired, weak, and short of breath. This common blood condition affects millions of people worldwide and can range from mild to severe, but the good news is that most types are treatable.

Anaemia of chronic disease occurs when long-lasting illnesses that cause inflammation affect your body’s ability to make enough healthy red blood cells, even when iron is stored in your tissues.

During pregnancy, your body works harder than ever to support both you and your growing baby. One common challenge many pregnant women face is anaemia—when your blood doesn’t have enough red blood cells to carry oxygen throughout your body. While mild anaemia is a normal part of pregnancy, understanding this condition and managing it properly is essential for your health and your baby’s development.

While anesthesia is generally very safe and complications are rare, neurological problems can sometimes occur during or after surgery. Understanding these risks and how they happen can help patients and medical teams work together to minimize complications and ensure the safest possible surgical experience.

An anal abscess is a painful, pus-filled pocket that forms near the anus or rectum when glands in the anal area become blocked and infected. Almost 90% of these abscesses are caused by blocked glands, and they require prompt medical attention to prevent serious complications.

Anal cancer is an uncommon cancer that develops in the tissues of the anal canal or near the opening of the anus, most often linked to infection with certain strains of the human papillomavirus (HPV). While symptoms can sometimes resemble common conditions like hemorrhoids, early detection and treatment often lead to successful outcomes.

Metastatic anal cancer, where the disease has spread to other organs, presents significant treatment challenges and requires careful coordination of care strategies.

When anal cancer returns after treatment, it presents new challenges that require careful evaluation and tailored approaches. Understanding your options and what to expect can help you and your medical team make informed decisions about the best path forward.

Stage 2 anal cancer means the tumor has grown larger than 2cm but has not yet spread to nearby lymph nodes or other parts of the body. Understanding this stage helps doctors choose the most effective treatment approach.

Stage 3 anal cancer means the cancer has not spread to distant parts of the body, but it may have grown into nearby organs or spread to nearby lymph nodes. Understanding your diagnosis and treatment options can help you make informed decisions about your care.

An anal fissure is a small tear in the lining of the anus that causes sharp pain and bleeding during bowel movements. While this common condition affects people of all ages, most cases heal with simple self-care measures within a few weeks.

An anal fistula is an abnormal tunnel connecting the inside of the anus to the skin outside, usually caused by an infected wound that drains pus. This painful condition affects everyday activities like sitting and walking, but with proper treatment, most people can return to normal life.

Anal incontinence is a condition where you lose control over when gas or stool passes from your body. This can happen suddenly or without you even realizing it, affecting your daily life and confidence.

Anal squamous cell carcinoma is a rare cancer that develops in the tissues lining the anal canal or around the anus. It affects about 11,000 people in the United States each year and is usually linked to infection with certain types of human papillomavirus (HPV). When caught early, this cancer is often curable.

Anaplastic large cell lymphoma T- and null-cell types is a rare form of cancer affecting white blood cells that help protect the body from disease. While this cancer can be aggressive and spread quickly, especially in its systemic forms, modern treatments offer hope for many patients, particularly those with certain genetic features.

Anaplastic lymphoma kinase (ALK) gene mutations play a key role in several types of cancer, particularly affecting younger people and nonsmokers with lung cancer.

Anaplastic thyroid cancer is one of the most aggressive forms of cancer affecting the thyroid gland, growing rapidly and often spreading to other parts of the body before diagnosis, yet recent advances in targeted treatments offer new hope for some patients.

Andersen-Tawil syndrome is a rare genetic disorder that affects the muscles, heart, and physical development, causing episodes of muscle weakness, abnormal heart rhythms, and distinctive physical features in those affected.

Androgenetic alopecia is the most common form of hair loss, affecting millions of men and women worldwide. While it can begin as early as the teenage years, this progressive condition typically becomes more noticeable with age, causing distinctive patterns of thinning and baldness that can significantly impact self-esteem and quality of life.

A ruptured aneurysm is a life-threatening medical emergency that occurs when a weakened, bulging section of a blood vessel bursts open and causes bleeding in the brain. This sudden event requires immediate medical attention and can lead to severe complications or death if not treated quickly.

Angelman syndrome is a rare genetic disorder that primarily affects the nervous system, causing severe developmental delays, intellectual disability, and problems with movement and speech. Despite these challenges, people with this condition often have a remarkably happy demeanor, with frequent smiling and laughter.

Angina pectoris is chest pain or discomfort that occurs when your heart muscle doesn’t receive enough oxygen-rich blood. This common symptom affects about 11 million people in the United States and serves as an important warning sign of underlying heart disease that requires proper diagnosis and treatment.

Angioimmunoblastic T-cell lymphoma is a rare and fast-growing blood cancer that affects T cells, a type of white blood cell that normally helps fight infection. This disease most commonly appears in older adults and often causes symptoms like fever, skin rash, and swollen lymph nodes throughout the body.

When angioimmunoblastic T-cell lymphoma does not respond to treatment or when the response does not last long, patients face complex decisions about next steps. Understanding what refractory disease means and what treatment options are available can help patients navigate this challenging situation.

Angiopathy is a general term that describes diseases of blood vessels, particularly when small vessels become damaged and fragile, leading to bleeding and other complications throughout the body.

Angiosarcoma is a rare and aggressive cancer that starts in the lining of blood vessels or lymph vessels, most often appearing on the skin of the head and neck but capable of developing almost anywhere in the body.

Metastatic angiosarcoma is an advanced and extremely aggressive form of a rare cancer that originates from blood or lymph vessel cells and has spread to other parts of the body, with survival measured in months rather than years.

Angiosarcoma is a rare and aggressive cancer that begins in the cells lining blood vessels or lymph vessels. When detected before it spreads to other parts of the body, it is called non-metastatic angiosarcoma. Understanding this condition, its symptoms, and treatment options can help patients make informed decisions about their care.

Recurrent angiosarcoma is a highly aggressive cancer that returns after initial treatment, presenting one of the most challenging situations in cancer care. Understanding the nature of recurrence and available treatment options can help patients and their families navigate this difficult diagnosis.

Ankylosing spondylitis is a long-term inflammatory disease that primarily affects the spine and can cause pain, stiffness, and reduced mobility. While there is no cure, various treatments and lifestyle approaches can help manage symptoms, improve quality of life, and potentially slow disease progression.

Anogenital dysplasia is a condition where cells in the genital or anal areas become abnormal. While these changed cells are not cancer, they could develop into cancer over time, making monitoring and treatment important.

Anogenital warts are small growths that appear on or around the genitals and anus, caused by certain types of human papillomavirus (HPV). While they’re one of the most common sexually transmitted infections, treatment options are available, and vaccines can help prevent them.

Anorexia nervosa is a serious eating disorder and mental health condition that affects nearly 30 million Americans during their lifetimes, carrying one of the highest death rates of any psychiatric illness—yet with proper treatment, recovery and healing are possible.