Read about carbon monoxide poisoning, including symptoms, causes, signs to look out for, what to do if you suspect a carbon monoxide leak, plus prevention advice.
Find out about cardiomyopathy, a general term for diseases of the heart muscle, where the walls of the heart chambers have become stretched, thickened or stiff.
Find out what cardiovascular disease (CVD) is, what problems it can cause, why it happens and how you can reduce your risk.
Catarrh is an excessive build-up of mucus in an airway or cavity of the body. Find out why it happens, what treatments you can try and when your GP can help.
Find out what a cavernoma is, what symptoms it can cause, and the importance of closely monitoring symptoms, plus how it's diagnosed and the possible treatment options.
Clostridium difficile, also known as C. difficile or C. diff, is a bacteria that can infect the bowel and cause diarrhoea. Find out what the symptoms are, who's most at risk and how it's treated.
Find out what a carcinoembryonic antigen (CEA) test is, why it's used and when it's carried out.
Find out about cervical rib, an extra rib that forms above the first rib. It does not usually cause problems, but sometimes it can lead to neck and shoulder pain, which spreads to the arm.
Charles Bonnet syndrome can cause a person whose vision has started to deteriorate to see things that aren't real (hallucinations). Find out what causes it, how to manage it, and where you can get help and support.
Read about chest infections, including the symptoms, what you can do to treat it yourself, and how a pharmacist and GP can help. A chest infection will usually get better on its own in about 7 to 10 days.
Find out what could be causing your chest pain and if you need to go to hospital or see a GP.
Find out what a Chiari malformation is, what problems it may cause, why it happens and how it can be treated.
Chilblains are small, itchy swellings on the skin that occur as a reaction to cold temperatures. They most often affect the body's extremities, such as the toes.
Find out what chiropractic is, how you can get it on the NHS or privately, and what the treatment involves.
A cholesteatoma is an uncommon abnormal collection of skin cells inside your ear.
Find out about chronic traumatic encephalopathy (CTE), a progressive brain condition that's thought to be caused by repeated blows to the head and repeated episodes of concussion.
Read about circumcision in boys, including why it's carried out, medical reasons for circumcision, what the procedure involves, recovery and risks.
Read about the medical reasons why circumcision in men may be necessary and what happens before, during and after the procedure.
Read about claustrophobia, including common triggers, physical and psychological symptoms, causes and treatment, plus help and support.
Find out more about cluster headaches, which are excruciating attacks of pain in one side of the head.
The tongue appears white or pale yellow and coated when the surface is colonised by bacteria or fungi, and dead cells become trapped between the small nodules on the tongue.
Find about colour vision deficiency and colour blindness, including how to get tested, why it happens, what problems it may cause and what can be done about it.
Read about what a coma is, how someone in a coma will be looked after, what you can do to help, and what happens when someone recovers from a coma.
Find out what compartment syndrome is, what the different types and symptoms are, and how it's treated.
Find out about concussion, a temporary injury to the brain, and what to do if you think you or someone in your care has it.
Costochondritis is the medical term for inflammation of the cartilage that joins your ribs to your breastbone (sternum).
Read about coughs, including what you can do to ease a cough, help from a pharmacist and when to see a GP.
Coughing up blood can be alarming, but isn't usually a sign of anything serious. Find out what you should do if you cough up blood and what the cause might be.
Read about cradle cap, a skin condition common in young babies. It's not serious and usually clears up on its own after a few weeks. There are things you can do to make it better.
Read about why CT scans are carried out, and find out what happens before, during and after the scan.
Cuts and grazes are common and can usually be treated at home. Read about how to treat them and when you should get medical advice.
Cyclical vomiting syndrome (CVS) is a rare condition that causes repeated episodes of being sick (vomiting) and feeling sick (nausea).
Find out what cyclospora is, what causes it, the symptoms, who's at risk and how it's treated.
Find out about cyclothymia, or cyclothymic disorder, a mild form of bipolar disorder.
Find out why caesarean sections are carried out, whether you can ask for one, what they involve, and what the risks are.
Read about cancer, a condition where cells in a specific part of the body begin to reproduce uncontrollably. The cancerous cells can invade and destroy surrounding healthy tissue.
A carotid endarterectomy is a surgical procedure to unblock a carotid artery. The carotid arteries are the main blood vessels that supply the head and neck.
Read about carpal tunnel syndrome (CTS), which causes pain and tingling in your hand when there's pressure on a nerve in your wrist. Find out what causes it and how to treat it.
Find out about the symptoms, causes and treatments for cartilage damage, and when you should seek medical attention.
Read about cataract surgery, a procedure to treat cataracts, where changes in the lens of the eye cause cloudy, blurry, or misty vision.
Cavernous sinus thrombosis is a blood clot in the cavernous sinuses. It can be life-threatening.
Cellulitis is a potentially serious infection in the deeper layers of your skin. Find out about the symptoms, causes, treatments and possible complications.
Find out about cerebral palsy, including the symptoms, causes, when to get medical advice, how it's treated and what the outlook is.
Cancer of the cervix often has no symptoms in its early stages. If you do have symptoms, the most common is unusual vaginal bleeding, which can occur after sex, in between periods or after the menopause.
Find out what cervical screening is and how it can help protect you from cervical cancer.
Read about cervical spondylosis, which is the medical term for neck pain caused by age-related "wear and tear" to bones and tissues.
Charcot-Marie-Tooth disease (CMT) is a group of inherited conditions that damage the peripheral nerves.
Chemotherapy is a treatment for cancer. There are different types of chemotherapy medicines, but they all work in a similar way. They stop cancer cells reproducing, which prevents them from growing and spreading in the body.
Chickenpox is a highly contagious infection that causes an itchy, spotty rash. Read more about chickenpox symptoms and when to get medical advice.
Find out about childhood cataracts which occur when changes in the lens of the eye cause it to become less transparent, resulting in blurred or misty vision.
Chlamydia is one of the most common sexually transmitted infection in the UK. Find out who is most at risk, where to get tested, and how it's treated.
Read about cholera, a potentially fatal bacterial infection caused by consuming contaminated food or water.
Read about why chorionic villus sampling (CVS) is offered, how it's carried out, and what the benefits and risks are.
Find out about chronic fatigue syndrome (CFS), also known as myalgic encephalomyelitis (ME). It's a long-term illness with a wide range of symptoms. Fatigue is the main symptom.
Read about chronic lymphocytic leukaemia (CLL), a type of cancer affecting the white blood cells that develops slowly over time. Find out about the symptoms, causes and treatments.
Find out what chronic myeloid leukaemia (CML) is, what the symptoms are, why it happens and how it's treated.
Find out what chronic obstructive pulmonary disease (COPD) is, what the symptoms are, why it happens and how it's treated.
Chronic pancreatitis is a condition where repeated inflammation permanently damages the pancreas.
Cirrhosis is scarring of the liver caused by long-term liver damage. The scar tissue prevents the liver working properly.
Find out about cleft lip and palate, where a baby is born with a gap in their upper lip and/or the roof of their mouth.
Read about depression, including how to tell if you're depressed, the treatments for different severities of depression, and how making lifestyle changes can help.
Information about clinical trials offered by the NHS and how to join one.
Find out about clubfoot (also called talipes), which is where the foot turns in, and how it's usually easy to treat.
Find out about coeliac disease, an autoimmune disease affecting the digestives system that makes a person have an adverse reaction to gluten.
Read about cognitive behavioural therapy (CBT), a talking therapy that can help you manage your problems by changing the way you think and behave.
Colic is when a baby cries a lot but there's no obvious cause. It's a common problem that should get better on its own. But call NHS 111 or see a GP if you're worried.
Find out about having a colostomy, including when it's needed, how it's carried out and recovery, plus information and advice about living with a colostomy.
Find out what a colposcopy is, why it's carried out, what happens and what the results mean.
Read all about the common cold, including what the symptoms are, how it's spread, how it's treated, and how you can prevent it.
Find out about complex regional pain syndrome (CRPS), a poorly understood condition where a person experiences persistent severe and debilitating pain.
Find out about the different types of congenital heart disease, why it happens, the signs and symptoms and how it's treated.
Conjunctivitis is where your eyes are red and sore. Read about what causes conjunctivitis, how to prevent it and how to treat it.
Find out what consent is, how it can be given, when it's needed, as well as situations when it's not needed.
Constipation is common and it affects people of all ages. You can usually treat it at home with simple changes to your diet and lifestyle.
Read about contact dermatitis, a type of eczema that causes inflammation of the skin when you come into contact with a particular substance.
A cornea transplant is an operation used to remove all or part of a damaged cornea and replace it with healthy cornea tissue from the eye of a suitable donor.
Corns and calluses are areas of thick, dry skin that develop when skin is exposed to excessive pressure or friction.
Cardiac catheterisation is an invasive diagnostic procedure that provides important information about the structure and function of the heart.
A coronary angioplasty is a procedure used to widen blocked or narrowed coronary arteries.
Find out why a coronary artery bypass graft (CABG) may be needed, plus what the procedure involves, how long it takes to recover and the associated risks.
Find out about coronary heart disease (CHD), including the main symptoms, causes, treatments and prevention. CHD is a major cause of death in the UK and worldwide.
Read about corticobasal degeneration (CBD), a rare condition where brain cells become damaged over time and certain sections of the brain start to shrink.
Read about counselling, a talking therapy that can help with a range of mental and emotional problems, including stress, anxiety and depression.
Find out about craniosynostosis, a rare condition where a baby's skull does not grow properly and their head becomes an unusual shape.
Find out about the different types of Creutzfeldt-Jakob disease (CJD), and what causes the condition and how it's treated.
Read more about the symptoms, treatment and complications of Crohn's disease, which is a long-term condition that causes inflammation of the lining of the digestive system.
Croup is a common childhood condition that causes a barking cough and cold-like symptoms. It's usually mild, but it's important to call 111 if you suspect your child has croup. They may need treatment.
Cushing's syndrome is a collection of symptoms that develop as the result of very high levels of a hormone called cortisol in the body.
Cystic fibrosis is an inherited condition in which the lungs and digestive system can become clogged with thick, sticky mucus. Read about the symptoms, causes and treatments.
Cystitis is inflammation of the bladder, usually caused by a bladder infection. Find out about the symptoms, causes and treatments for this common condition.
Find out what a cystoscopy is, what it's used for, whether it's painful, and if there are any risks involved.
Cytomegalovirus (CMV) is a common virus that is part of the herpes family of viruses.
Find out what chronic kidney disease (CKD) is, including what the symptoms are, how it's diagnosed and how it can be treated.
Find out about coccydynia (tailbone pain), including what the symptoms are, when to get medical advice, why it happens and how it's treated.
Cold sores are common and usually clear up on their own within 10 days. They're contagious until they go away.
Complementary and alternative medicines (CAMs) are treatments that fall outside of mainstream healthcare.
Chipping, breaking or cracking a tooth isn't usually serious. Your dentist will usually be able to treat it.
Read information about cosmetic procedures.
A colonoscopy is a test to check inside your bowels. This test can help find what's causing your bowel symptoms.
NHS advice about coronavirus (COVID-19), including information on symptoms, testing, vaccination and self-isolation.