Demyelination occurs when the protective covering around your nerve cells becomes damaged, disrupting the way your nerves send messages throughout your body and potentially affecting movement, vision, sensation, and other vital functions.

Dengue fever is a mosquito-borne viral illness that affects millions of people each year worldwide, causing symptoms ranging from mild flu-like fever to life-threatening complications that require immediate medical attention.

Dent’s disease is a rare genetic kidney disorder that primarily affects males, causing proteins and calcium to leak into the urine, leading to kidney stones and, in many cases, progressive kidney damage that can result in kidney failure in adulthood.

Depression is a common mental health condition that affects millions of people worldwide, causing persistent sadness and changes in how you think, sleep, eat, and function in daily life. While it’s more than just feeling down, effective treatments are available that can help people recover and return to normal activities.

Dermatitis is a common condition that causes inflammation, redness, and itching of the skin, affecting millions of people worldwide and ranging from mild discomfort to significant disruption of daily life.

Atopic dermatitis is a long-lasting skin condition that causes dry, itchy, and inflamed skin. While it most commonly begins in childhood, it can affect people at any age and requires ongoing care to manage symptoms and prevent flare-ups.

Dermatomyositis is a rare condition that causes muscle weakness and distinctive skin rashes. While there is no cure, treatment can help improve muscle strength and clear the skin changes, allowing many people to manage their symptoms and maintain their quality of life.

Desmoid tumours are rare, noncancerous growths that develop in connective tissue throughout the body. Although they don’t spread like cancer, they can grow aggressively into nearby structures, causing pain and serious health problems.

Desmoplastic melanoma is a rare and unusual form of skin cancer that often looks like a scar rather than a typical mole or dark spot. It accounts for less than 4% of all melanomas and tends to appear on sun-damaged skin of older adults, particularly on the head and neck.

Desmoplastic small round cell tumour is a very rare and aggressive type of cancer that typically develops in the abdomen and pelvis, most often affecting young males between the ages of 10 and 30.

Developmental dysplasia of the hip is a condition where the hip joint does not form properly in babies and young children, causing the ball of the hip to fit poorly in its socket or even slip out of place completely.

Over half of the nearly 2 million healthcare-associated infections can be traced back to implanted medical devices—a growing concern as more people rely on these life-saving technologies to manage serious health conditions.

Diabetes insipidus is a rare condition that makes your body lose its ability to balance water properly. While most people make 1 to 3 quarts of urine a day, people with this condition can make up to 20 quarts, leading to constant thirst and frequent trips to the bathroom day and night.

Diabetes mellitus is a condition that affects how your body manages blood sugar, impacting millions of people of all ages worldwide. While it cannot be cured, it can be effectively managed through a combination of lifestyle changes, medications, and regular monitoring to help you live a healthy, fulfilling life.

Diabetic autonomic neuropathy is a serious complication of diabetes that affects the nerves controlling automatic body functions. It can impact your heart rate, blood pressure, digestion, bladder, sexual function, and more. Understanding this condition is essential for managing symptoms and maintaining quality of life.

Diabetic foot problems are a serious complication that can develop when high blood sugar levels damage the nerves and blood vessels in your feet. While these complications can be severe, including the risk of amputation, most can be prevented through careful daily foot care and good diabetes management.

Diabetic foot infection is one of the most common and serious complications of diabetes, and the most frequent cause of hospitalization and nontraumatic amputation in people with diabetes. Early diagnosis and proper treatment are essential to prevent severe complications.

When diabetes affects the stomach’s ability to empty properly, food can sit too long, causing uncomfortable symptoms and making blood sugar control even more challenging.

Diabetic ketoacidosis is a serious and life-threatening emergency that can happen when your body doesn’t have enough insulin to use blood sugar for energy. Instead, your body breaks down fat too quickly, creating harmful acids called ketones that build up in your blood and make it too acidic.

Diabetic nephropathy is a serious kidney disease caused by diabetes that affects millions of people worldwide. It develops slowly over many years and can eventually lead to kidney failure if not properly managed. Understanding this condition and taking early action can help protect your kidneys and improve your overall health.

Diabetic neuropathy is nerve damage caused by diabetes that can affect up to half of all people living with the condition, causing pain, numbness, and other serious complications throughout the body.

Diabetic retinal oedema is a serious eye condition that can affect people with diabetes, where fluid builds up in the macula at the center of the retina, potentially leading to vision loss. With early detection and proper treatment, progression can be slowed or even reversed.

Diabetic retinopathy is a serious eye complication of diabetes that affects blood vessels in the retina and stands as a leading cause of blindness in working-age adults, yet early detection and proper management can significantly protect your vision.

Diarrhoea is one of the most common health problems affecting people of all ages worldwide. While usually mild and temporary, lasting only a few days, it can sometimes signal a more serious condition requiring medical attention. Understanding its causes, recognizing warning signs, and knowing how to manage symptoms can help prevent complications like dehydration.

Diffuse large B-cell lymphoma is the most common type of non-Hodgkin lymphoma, affecting thousands of people each year. Although it grows quickly, this aggressive blood cancer often responds well to treatment, and many people can be cured, especially when diagnosed and treated early.

When diffuse large B-cell lymphoma returns after treatment, it presents new challenges—but also new treatment options. Understanding relapse, recognizing the signs, and knowing what therapies are available can make a significant difference in managing this aggressive blood cancer.

When diffuse large B-cell lymphoma stops responding to treatment or comes back after a period of improvement, patients face a challenging situation that requires specialized care and newer treatment approaches.

Diffuse large B-cell lymphoma (DLBCL) stage I is a fast-growing but often curable blood cancer that affects only one group of lymph nodes in a single area of the body. Although aggressive, early-stage DLBCL responds well to treatment, with many people achieving complete remission.

Diffuse large B-cell lymphoma stage II is a fast-growing blood cancer that affects lymph nodes on the same side of the diaphragm. While this cancer is aggressive, it is often treatable and curable, especially with early diagnosis and treatment.

Diffuse large B-cell lymphoma stage III is a fast-growing blood cancer affecting the lymphatic system, requiring immediate treatment with powerful drug combinations that can often lead to remission and cure.

Stage 4 diffuse large B-cell lymphoma is an advanced form of blood cancer where the disease has spread beyond the lymphatic system to other organs of the body. Despite its aggressive nature, this cancer often responds well to treatment, and many people can achieve remission or even be cured.

Dilated cardiomyopathy is a disease where the heart muscle stretches and weakens, making it harder for the heart to pump blood effectively throughout the body. While some people may not notice symptoms at first, this condition can become life-threatening and is a common cause of heart failure.

Diminished ovarian reserve affects about 10 to 30 percent of women seeking help for infertility, yet many who receive this diagnosis can still achieve pregnancy with proper care and treatment options tailored to their individual circumstances.

Diphtheria is a serious bacterial infection that can affect your throat, nose, and sometimes skin, creating a thick coating that can block your airway and spread toxins throughout your body.

Diverticulitis is inflammation of small pouches that bulge out through weak spots in the colon wall. While these pouches are common as we age, when they become inflamed or infected, they can cause sudden, severe pain and other serious symptoms that require medical attention.

Dizziness is one of the most common reasons people visit healthcare professionals, affecting approximately 20% to 30% of people at some point in their lives. While it can be alarming and disruptive to daily life, most cases of dizziness can be effectively treated once the correct cause is identified.

When the body’s natural DNA correction system fails, the consequences can range from increased cancer risk to accelerated aging. Mutations in genes responsible for DNA mismatch repair disrupt one of the cell’s most essential quality control mechanisms.

Double hit lymphoma is an aggressive form of cancer that develops from white blood cells called B lymphocytes, characterized by specific genetic changes that make it particularly challenging to treat.

Drug dependence is a condition where your body becomes so used to a substance that you need it to function normally, and stopping it makes you feel unwell. While often confused with addiction, dependence can occur even with prescribed medications, and understanding the difference is crucial for recognizing when help is needed.

Drug eruptions are skin reactions that happen when your body responds to a medication. While most are mild and disappear after stopping the medicine, some can become serious and even life-threatening, requiring immediate medical attention.

Drug use disorder is a treatable mental health condition where you experience a problematic pattern of substance use that affects your health, relationships, and daily life. While it can be life-threatening, recovery is possible for everyone with the right support and treatment.

Dry age-related macular degeneration is a common eye condition that affects central vision, particularly in people over 50. While it progresses slowly and doesn’t cause complete blindness, understanding this condition and how to manage it can help preserve your quality of life and independence.

Dry eye is a common condition that affects millions of people when tears cannot properly lubricate the eyes, causing discomfort and sometimes affecting vision. Understanding the causes and available treatments can help you find relief and protect your eye health.

Dry mouth, also called xerostomia, occurs when your salivary glands don’t produce enough saliva to keep your mouth wet. While everyone experiences occasional dry mouth when nervous or stressed, persistent dryness can make chewing, swallowing, and speaking difficult, and significantly increases your risk of tooth decay and oral infections.

Duchenne muscular dystrophy is a severe genetic disorder that progressively weakens muscles throughout the body, primarily affecting boys and leading to difficulties with movement, breathing, and heart function.

Pancreatic ductal adenocarcinoma is the most common and deadliest form of pancreatic cancer, affecting thousands of people each year. Understanding this disease, its symptoms, and treatment options can help patients and their families navigate the difficult journey ahead.

Dupuytren’s contracture is a hand condition that causes one or more fingers to bend toward the palm, making them impossible to straighten completely. This gradual condition affects the tissue beneath the skin and most commonly impacts the ring and little fingers.

Dyskinesia refers to involuntary, uncontrolled movements that can affect different parts of the body. While often linked to Parkinson’s disease treatment, it’s not a symptom of the disease itself, but rather a complication that can develop from certain medications.

Dyslipidaemia is a condition where the levels of fats in your blood are not in the healthy range, which can increase your risk of heart disease and stroke.

Dysmenorrhoea, the medical term for painful menstrual periods, affects more than half of women who menstruate and is one of the most common reasons for school and work absence among those of reproductive age.

Dyspepsia, commonly known as indigestion, is a widespread digestive problem affecting up to one in four people at some point in their lives, causing discomfort in the upper belly that can range from mild to severe.

Dyspnoea, commonly known as shortness of breath, is the uncomfortable feeling that you cannot get enough air into your lungs. It can affect your daily activities and quality of life, but understanding its causes and learning to manage it can help you breathe easier.

Dystonia is a movement disorder that causes muscles to contract involuntarily, leading to twisting motions, repetitive movements, or unusual postures that a person cannot control. The condition can affect one part of the body or spread to multiple areas, and while there is no cure, various treatments can help manage symptoms and improve quality of life.

Dystonic tremor is a specific type of shaking that occurs when muscles tense up involuntarily due to dystonia, a disorder that causes unwanted muscle contractions.

Ear discomfort is one of the most common reasons people visit their healthcare providers, affecting both children and adults. While ear pain can be uncomfortable and worrying, it usually isn’t dangerous and often improves on its own within a few days.

Early onset familial Alzheimer’s disease is a rare inherited form of dementia that strikes people before age 65, sometimes as early as their 30s or 40s, caused by specific genetic mutations passed down through families.

The ECOG Performance Status Scale is a widely used tool that helps doctors measure how cancer affects a patient’s ability to perform daily activities and care for themselves, playing a crucial role in treatment decisions and predicting outcomes.

Ebola disease is a rare but severe illness caused by viruses that can lead to serious complications and death. While outbreaks primarily occur in parts of Africa, understanding how the disease spreads and recognizing symptoms early can save lives.

Eclampsia is a rare but serious pregnancy complication where a woman with high blood pressure suddenly experiences seizures. Though affecting fewer than 1% of pregnant women with high blood pressure, this medical emergency requires immediate treatment to protect both mother and baby.

ENPP1 Deficiency is a rare genetic disorder that causes serious problems throughout a person’s life, from life-threatening blood vessel calcification in babies to painful bone and joint issues in children and adults.