Find out what causes dandruff, what you can do to get rid of it and when to get medical advice.
Decongestants are medicines that can provide short-term relief for a blocked or stuffy nose (nasal congestion). Find out about the different types and who can take them.
Find out more about dental abscesses, including what the symptoms are, when to get medical help, how they’re treated, and how to prevent them.
NHS information about dentures, including how they're fitted, how to care for them and when to see a dentist.
Find out more about dyspraxia, which is a common disorder that affects movement and co-ordination. Read about the symptoms, causes and treatments for dyspraxia, and find out when to get medical help.
Developmental dysplasia of the hip is a condition where the ball and socket joint of the hips does not properly form in babies and young children.
Read about the main types of diabetes, a condition that causes a person's blood sugar level to become too high.
Find out who should have diabetic eye screening, why it's done and what happens, and when you’ll get your results.
Find out about diabetic ketoacidosis (DKA), including what the symptoms are, when to get medical help and how to prevent it.
Find out about DiGeorge syndrome (22q11 deletion), including why it happens and what problems it can cause.
Find out how to tell if you have a dislocated kneecap, where to get medical help, what the treatments are, and how long it takes to recover.
Find out how to tell if your shoulder is dislocated, how and where to get medical help, and how long it takes to recover.
Find out about differences in sex development (DSDs), a group of rare conditions where the reproductive organs and genitals don't develop as expected. Some people prefer to use the term intersex.
Find out about diverticular disease and diverticulitis, common conditions affecting the large intestine (bowel).
Dizziness is a common symptom that’s not usually a sign of anything serious. Find out what you can do about it and when to get medical help.
Find out about dry mouth, including what causes it and things you can do to help ease it yourself.
Find out more about dysarthria, which is where you have difficulty speaking because the muscles used for speech are weak.
Find out about dysentery, including the symptoms, when to see a GP, treatment, how to reduce your risk of getting it and how to avoid passing it on to others.
Read about deafblindness, a condition in which a person has a combination of sight and hearing difficulties that affect their everyday activities.
Find out more about DVT (deep vein thrombosis), a blood clot in a vein, usually in the leg.
Dehydration is when your body loses more fluid than you take in. Find out what the symptoms of dehydration are, how to prevent it and when to get medical help.
Find out about a type of dementia called dementia with Lewy bodies, including what the symptoms are, how it's treated and what the outlook is.
Dengue is an infection spread by mosquitoes. Find out where it's found, what the symptoms are, when to get medical help, and what you can do to avoid it.
Read about developmental co-ordination disorder (DCD), also known as dyspraxia, a condition that affects physical co-ordination.
Diabetes insipidus is a rare condition where you produce a large amount of urine and often feel thirsty.
Find out more about diabetic retinopathy, a complication of diabetes, caused by high blood sugar levels damaging the back of the eye (retina).
Dialysis involves removing waste products and excess fluid from the blood when the kidneys stop working properly. Blood is diverted to a machine to be cleaned.
Diphtheria is a potentially fatal contagious bacterial infection that mainly affects the nose and throat, and sometimes the skin. It is very rare in England.
Read about discoid eczema (nummular or discoid dermatitis), a long-term (chronic) skin condition that causes the skin to become itchy, reddened, dry and cracked
Find out about double vision (diplopia), including how to tell if you have it, what can cause it and when to get medical help.
Down's syndrome is when you're born with an extra chromosome.
Find out what causes dry eyes and what you can do to help ease it.
Find out about Dupuytren's contracture (Dupuytren's disease), which affects the hands and fingers and causes 1 or more fingers to bend into the palm of the hand.
Read about dyslexia, a common type of learning difficulty that can cause problems with reading, writing and spelling.
Dystonia is the name for uncontrolled and sometimes painful muscle movements (spasms). Find out about the main symptoms, types and treatments.
Read about a detached retina, which is where the thin layer at the back of the eye (retina) becomes loose from the back of the eye. Find out what the symptoms are, what causes it and how it's treated.
Find out more about dysphagia, where you have problems swallowing.
Diarrhoea and vomiting are common in adults, children and babies. Find out how to treat and avoid spreading them, and when to get medical help.
DNACPR means if your heart or breathing stops your healthcare team will not try to restart it. A DNACPR decision is made by you and/or your doctor or healthcare team.
Read our guide on dementia, which covers possible causes, symptoms and treatments, plus guidance for family and friends on living with dementia.
Dissociative disorders are a group of conditions where you may feel disconnected from reality. Find out more, including where to get help.
Read about depression in adults, including how to tell if you're depressed, the treatments for different severities of depression, and how making lifestyle changes can help.
Find out how diaphragms and caps work to prevent pregnancy, how effective they are, where to get them and how to use them.