Read about neuroendocrine tumours and their symptoms, known as carcinoid syndrome. Find out the causes, tests and treatments for neuroendocrine tumours and carcinoid syndrome.
Read about hyperacusis, an intolerance to sounds that are not an issue for most other people. Find out about the symptoms, causes and treatments.
Nail patella syndrome is a rare genetic condition that can involve problems with the nails, bones, kidneys and eyes. It's thought to affect about 1 in 50,000 people.
Find out about different nail problems, including brittle or crumbly nails, thickened, overgrown nails, or changes in nail colour.
Nasal and sinus cancer affects the nasal cavity and sinuses. Find out about the symptoms, causes, treatments and outlook, with links to more information.
Find out what nasopharyngeal cancer is, what the signs and symptoms are, what causes it, and how it's diagnosed and treated.
Read about neck pain or a stiff neck, which is a common problem and generally nothing to worry about.
Necrotising fasciitis is a rare but serious bacterial infection that affects the soft tissue under the skin. Find out what the symptoms are and how it's treated.
Information on neonatal herpes (herpes in newborn babies), with links to other useful resources.
Read about nephrotic syndrome, a condition that causes the kidneys to leak large amounts of protein into the urine. This can lead to a range of problems.
Find out what neuroblastoma is, what the symptoms are, how it's diagnosed and how it's treated.
NHS information about neuroendocrine tumours (NETs) including symptoms, causes and treatments.
Read about neuromyelitis optica, a rare condition that affects the spinal cord and the nerves of the eyes (optic nerves). Find out about the symptoms, causes and treatments.
Find out about night sweats, including what they are and what might be causing them, and when to get medical help.
Many children experience nightmares and night terrors, but most grow out of them. They don't cause any long-term harm to your child.
Read about nipple discharge, including what can cause it and when to see a GP. It's usually nothing serious, but sometimes it's a good idea to get it checked.
Non-alcoholic fatty liver disease (NAFLD) is caused by a build-up of fat in the liver. It often affects overweight or obese people. Although NAFLD doesn't usually cause serious problems, you should take steps to stop it getting worse.
Read all about norovirus, including how it's spread, what the symptoms are, when to get medical advice and how to stop it spreading.
Read about non-steroidal anti-inflammatory drugs (NSAIDs), a widely used medicine for relieving pain, reducing inflammation, and bringing down a high temperature (fever).
Jaundice is a common and usually harmless condition in newborn babies that causes yellowing of the skin and the whites of the eyes.
Read about narcolepsy, including the symptoms, causes, and how it's diagnosed and treated.
Find out about nasal polyps, which are painless soft growths inside your nose. Read about the symptoms, causes, treatments and when to see a GP.
Read more about newborn respiratory distress syndrome (NRDS), a serious condition where a newborn baby's lungs cannot provide their body with enough oxygen. It can be treated before or after birth.
Neurofibromatosis type 1 (NF1) is a genetic condition that causes tumours to grow along your nerves. The tumours are usually non-cancerous and so usually cause only mild symptoms.
Neurofibromatosis is the name for a number of genetic conditions that cause tumours to grow along your nerves. Neurofibromatosis type 2 (NF2) is a rarer form of the condition.
Non-allergic rhinitis is inflammation of the inside of the nose that isn't caused by an allergy.
Read about urethritis, non-gonococcal urethritis and non-specific urethritis. Urethritis is inflammation of the urethra and is usually caused by an infection.
Non-Hodgkin lymphoma is an uncommon cancer that develops in the lymphatic system, which is a network of vessels and glands spread throughout your body.
Read about Noonan syndrome - a genetic disorder that causes a wide range of features, such as heart abnormalities and unusual facial features.
Read about the causes of nosebleeds, how to treat them at home and when you should get medical advice.
The NHS Health Check is a health check-up for adults in England aged 40 to 74.
Find out about the different types of screening offered by the NHS in England.