Find out how to check if your child has a high temperature (fever), what you can do to bring their temperature down, and when to get medical help.
Read about reactions to hair dye, the signs, symptoms, how to avoid them and what to do when you have a reaction.
Read about hamstring injuries, including the different types, how they're treated and how long it takes to recover.
Read about hand, foot and mouth disease. Find out what the symptoms are, how to treat it, and when you should get medical advice.
Read about the main types of cancer that affect the head and neck, including mouth cancer, laryngeal cancer and throat cancer.
Read about when hearing tests are routinely offered to children, what they involve and why they're important.
Find out what heart palpitations are, what they feel like, common causes and when to get medical help.
Heat exhaustion and heatstroke can happen if you get too hot. They can be serious. They usually happen during a heatwave or in a hot climate, but can also be caused by very intense exercise.
Read about heat rash, also called prickly heat or miliaria rubra, which is an itchy rash of small, raised spots and a stinging or prickling sensation on the skin.
NHS information about Henoch-Schönlein purpura (HSP), including what the symptoms are, when to get medical help and treatments.
Hepatitis is the term used to describe inflammation of the liver. It's usually the result of a viral infection or liver damage caused by drinking alcohol.
Read about herbal medicines and remedies, including what the possible risks are, who shouldn't use them, and what to look for when buying them.
Read information on hereditary haemorrhagic telangiectasia (Osler-Weber-Rendu syndrome), including symptoms, causes and how it's treated.
Read about hereditary neuropathy with pressure palsies (HNPP), an inherited nerve disorder that typically causes numbness, tingling and muscle weakness.
Find out about hereditary spastic paraplegia (HSP), a rare group of inherited disorders that often cause weakness and stiffness in the leg muscles, which gradually gets worse over time.
Read about hernias, which occur when an internal part of the body pushes through a weakness in the muscle or surrounding tissue wall.
Find out about herpes simplex eye infections, including what the symptoms are, when and where to get medical help and how they're treated.
Find out about herpetic whitlow (whitlow finger) including symptoms, causes and treatments.
Find out about haemophilus influenzae (Hib),including what the symptoms are, what causes it, and the vaccines that can help prevent it.
Find out about hidradenitis suppurativa, a painful, long-term skin condition that causes abscesses and scarring on the skin.
Find out about high blood sugar (hyperglycaemia), including what the symptoms are, what a high blood sugar level is and how to control your blood sugar.
Find out about common causes of hip pain in adults, how you can help ease hip pain and when you should get medical help.
Hirschsprung's disease is a rare bowel condition that is mainly diagnosed in babies and young children. Read about the symptoms, causes and treatments.
Find out about homeopathy, including how it has developed and used in treatments, plus links to other resources.
Information about home oxygen therapy, also known as home oxygen treatment, including when it's needed, how it's given, the assessment process and safety advice.
Homocystinuria (HCU) is a rare but potentially serious inherited condition where the body can't process the amino acid methionine.
Read more about hypnotherapy, which is a type of complementary therapy that uses hypnosis – an altered state of consciousness.
Find out about hypothermia, a dangerous drop in body temperature below 35C (normal body temperature is around 37C). Go to A&E or call 999 immediately if someone has symptoms of hypothermia.
Find out about hip pain in children, including what causes it, when to get medical help and how it can be treated.
Find out about haemochromatosis, an inherited condition where iron levels in the body slowly build up over many years.
Find out about the causes, symptoms and treatment of haemophilia, an inherited condition that means you bleed more than usual.
Hair loss can have many causes. Alopecia is the general medical term for hair loss. Find out when to see a GP and what treatments are available.
Find out about when hand tendon repair is needed, how surgery is carried out, the recovery process and possible complications.
If you're considering having an operation or your GP has suggested you may need surgery, this guide is for you.
Find out about the symptoms and causes of hay fever, who's affected and what treatments are available.
Find out how to spot head lice, how to get rid of them and how they spread.
Find out about the common signs and causes of hearing loss, when to get medical help and how hearing loss is treated.
Read about hearing tests that are used to assess your ability to hear different sounds and to determine if there are any problems.
Find out about heart attacks, a serious medical emergency in which the supply of blood to the heart is suddenly blocked, usually by a blood clot.
Heart block is a condition where the heart beats more slowly or with an abnormal rhythm. Find out what causes it and how it's treated.
Find out more about heartburn, a burning feeling in the chest caused by stomach acid travelling up towards the throat (acid reflux). If it keeps happening, it may be gastro-oesophageal reflux disease (GORD).
Find out what heart failure is, including what the symptoms are and how it is treated.
Find out about heavy periods (called menorrhagia) and how to treat them if they are affecting your daily life.
Find out about hepatitis A, including what causes it, how it can be prevented, what the symptoms are, and how it is treated.
Find out about hepatitis B, what causes it, how it’s prevented, what the symptoms are, how it is treated and what the complications may be.
Read about hepatitis C, a virus that can infect and damage the liver. Find out about the symptoms, causes and treatments for the condition.
Find out what causes a hiatus hernia, which is when part of your stomach moves up into your chest, and how to treat it if needed.
Find out about things you can do yourself to stop or prevent hiccups.
Find everything you need to know about high blood pressure, including causes, symptoms, diagnosis and treatment, with links to other useful resources.
Find out what cholesterol is, what causes high cholesterol, why it's important to keep your cholesterol levels under control, and how to lower your cholesterol.
Read about the symptoms of HIV and AIDS, what treatments are available and how to prevent getting or spreading the infection.
Find out about hives (also called urticaria), which is a raised, itchy rash that's usually caused by a reaction to things like food, pollen, insect bites or chemicals.
Hodgkin lymphoma is an uncommon cancer that develops in the lymphatic system, which is a network of vessels and glands spread throughout your body.
Find out more about Huntington's disease, an inherited condition that damages certain nerve cells in the brain.
Find out about hydrocephalus (fluid in the brain), including information about symptoms, causes, types, diagnosis, treatment and complications.
Read about hydronephrosis, a condition where one or both kidneys become stretched and swollen as a result of a build-up of urine inside them.
Find out about hysterectomy, a surgical procedure to remove the womb (uterus). You'll no longer be able to get pregnant after the operation.
Find out about hysteroscopy, a procedure used to examine the womb (uterus) to diagnose and treat some women's health conditions.
Read about head injuries and concussion, what symptoms to look out for, when to seek medical advice or treatment and how to care for a minor head injury.
Read about some of the main types of headaches, and find out when you should get medical advice.
Find out about hyperparathyroidism, where the parathyroid glands produce too much parathyroid hormone.
Hypoparathyroidism is a rare condition where the parathyroid glands, which are in the neck near the thyroid gland, produce too little parathyroid hormone.
Many women experience headaches caused by changes in their hormones. Read self-help tips and treatments for hormone headaches, also called menstrual migraines.
Find out what human papillomavirus (HPV) is, how it's spread, what conditions it can cause, and how to protect against it.
Find out about high temperature (fever) in adults including what causes it, how to tell if you have a high temperature and how to treat it.
Find out about how to get hearing aids, and the different types of hearing aids and implants.
Find out about what causes heel pain and what you can do to ease the pain yourself.
Find out about treatments for hand pain, when to get medical help and possible causes.
Find out what a hip replacement involves, when it might be recommended, and how it can help with hip pain and movement.
Read about hoarding disorder, including why it might happen, why it's a problem and what can be done about it.
Health anxiety is when worrying about your health starts to take over your life. Read NHS advice about symptoms and and what to do if you have it.
Where to get help if you are having suicidal thoughts, and what to do if you are worried about someone else.
Find out about hallucinations and hearing things, including signs, causes and treatments.
Find out about the hepatitis B vaccine, including why it’s given, who can have it and what side effects it can have.
Find out about the Hib/MenC vaccine, including what it's for, who should have it and how to get it.
Find out about the HPV vaccine, including who it's for, how to get it and possible side effects.