Find out about prosopagnosia, a difficulty recognising people's faces. Read about the symptoms, causes and things you can do to help live with it.
Find out about Patau's syndrome, also known as trisomy 13, a serious genetic disorder where a baby has an extra copy of chromosome 13.
Peak flow is a simple measurement of how quickly you can blow air out of your lungs. Read about why and how it's measured.
Find out about common causes of pelvic pain in adults, how you can ease pelvic pain and when you should get medical help.
Find out about period pain, including symptoms, causes, when to see a GP, diagnosing underlying conditions, and treatment.
Find out about periods, including when they usually start and finish, period products, PMS, getting pregnant, and changes to your periods.
Find out more about persistent trophoblastic disease and choriocarcinoma, part of a very rare group of tumours called gestational trophoblastic tumours (GTTs).
Find out about positron emission tomography (PET) scans and how these three-dimensional images of the inside of the body can be used.
Read about phaeochromocytoma, a rare tumour of the adrenal glands, which sit above the kidneys. They're usually benign (non-cancerous), although some are cancerous.
Find out about phenylketonuria (PKU), a rare genetic condition that's present from birth (congenital), where the body is unable to break down phenylalanine.
Find out about phlebitis (superficial thrombophlebitis), including what the symptoms are, what causes it, when to get medical help and how it’s treated.
Find out when a phosphate test may be needed and what it's used for.
Find out what photodynamic therapy (PDT) involves, when it's used and the risks you should be aware of.
Read about pins and needles (paraesthesia), a pricking, burning, tingling or numbing sensation that's usually felt in the arms, legs, hands or feet.
Find out about faulty PIP breast implants, including why they are banned, and the latest safety information on removal and replacement.
Find out about pityriasis rosea, including what the symptoms are and what to do if it's uncomfortable or itchy.
Find out about pityriasis versicolor (sometimes called tinea versicolor), including what the symptoms are, how it’s treated and how you get it.
Find out about why some babies develop a slightly flattened head, what can be done about it, and how long it will take to improve.
Find out more about pleurisy, where inflammation around the lungs causes sharp chest pain.
Find out more about polio, including where it's found, what the symptoms are and how to prevent it.
Find out about polyhydramnios (too much amniotic fluid), including symptoms, how it's treated and what it means for your pregnancy and baby.
Polymorphic light eruption is a fairly common skin rash triggered by exposure to sunlight or artificial ultraviolet light. It lasts for up to 2 weeks, healing without scarring.
Find out about pompholyx (also called dyshidrotic eczema), including what the symptoms are, how it’s treated and what you can do to ease the symptoms.
Find out about postmenopausal bleeding, what could be causing it, when to get medical help and what treatments are available.
A post-mortem, also known as an autopsy, is the examination of a body after death. The aim of a post-mortem is to determine the cause of death.
Find out more about postural tachycardia syndrome (PoTS), where your heart rate increases very quickly after getting up from sitting or lying down.
Find out why and when a potassium test may be needed.
Cancer is not usually inherited, but some types – mainly breast, ovarian, colorectal and prostate cancer – can be strongly influenced by genes and can run in families.
Probiotics are thought to help restore the natural balance of bacteria in your gut when it's been disrupted by an illness or treatment. There's some evidence that probiotics may be helpful in some cases, but there's little evidence to support many health claims made about them.
If you or someone you care for struggles to swallow pills, you should discuss it with a doctor or pharmacist.
Prostate problems are common in men, particularly in those over 50 years of age.
Find out about prostatitis, including what the symptoms are, where to get medical help, what you can do to ease the symptoms, how it's treated and causes.
Find out about psoriatic arthritis, including what the symptoms are, how it's treated, what causes it and when to get medical help.
Find out about pubic lice, including what they look like, how you get them, symptoms, when to get medical advice, treatment and complications.
Find out about pudendal neuralgia (nerve pain in the genitals, bottom, anus or pelvis), including what the symptoms are and how it's diagnosed and treated.
Find out about pyoderma gangrenosum, a rare skin condition that causes painful ulcers.
Find out what a pacemaker is, how it works, why you might need it, and how it's implanted.
Find out about Paget's disease of bone, a condition where the normal cycle of bone renewal and repair is disrupted.
Find out about Paget's disease of the nipple (Paget's disease of the breast). It's a rare condition where eczema-like changes occur in the skin of the nipple and areola.
Find out about paralysis, including symptoms, causes and treatments.
Read about Parkinson's disease, a condition in which parts of the brain become progressively damaged over many years.
Pelvic inflammatory disease (PID) is an infection of the female reproductive system, including the womb, fallopian tubes and ovaries.
Pelvic organ prolapse (POP) is bulging of 1 or more of the pelvic organs into the vagina.
Find out about pemphigus vulgaris, including what the symptoms are, how it’s treated and why it happens.
NHS information about perforated eardrum, including symptoms, when to get medical help, treatments and causes.
Find out about pericarditis, including symptoms, when to get help, treatment and causes.
Read about peripheral arterial disease (PAD), a common condition in which a build-up of fatty deposits in the arteries restricts blood supply to leg muscles.
Find out about peripheral neuropathy, a term for a group of conditions in which the peripheral nervous system is damaged.
Find out about peritonitis, which is inflammation of the thin layer of tissue that lines the inside of your abdomen (tummy), called the peritoneum.
Read about physiotherapy, including why it's used, what it involves and how you can access it on the NHS or privately.
Find out about piles (haemorrhoids), including what the symptoms are, how they're treated and what causes them.
NHS information about pilonidal sinus, which is a small hole or tunnel in the skin at the top of your bottom. Find out what the symptoms are and when to see a GP.
Read NHS information about plastic surgery, which is a type of surgery that repairs and reconstructs missing or damaged tissue and skin.
Find out about pneumonia, including what the symptoms are, where to get medical help, what the treatments are, what causes it and how to prevent it.
Read about the signs and symptoms of poisoning and find out what to do if you think someone has been poisoned.
Read about polycystic ovary syndrome (PCOS), a common condition that affects how a woman's ovaries work.
Find out about polymyalgia rheumatica (PMR), a condition that causes pain, stiffness and inflammation in the muscles around the shoulders, neck and hips.
Read about post-herpetic neuralgia, which is persistent nerve pain at the site of a previous episode of shingles.
Post-polio syndrome (PPS) is a poorly understood condition that can affect people who have had polio in the past. Polio is a viral infection that used to be common in the UK but is rare nowadays.
Find out about Prader-Willi syndrome (PWS), which is a rare genetic condition that causes a wide range of physical symptoms, learning difficulties and behavioural challenges.
Pre-eclampsia is a condition that affects some pregnant women, usually during the second half of pregnancy (from around 20 weeks) or soon after their baby is delivered.
Find out more about PMS (premenstrual syndrome), the symptoms women can experience before their period, and premenstrual dysphoric disorder (PMDD).
Find out about pressure ulcers (pressure sores or bed sores), which are areas of damage to your skin and the tissue underneath.
Read about priapism, a persistent, often painful erection. If it lasts for more than 3 to 4 hours, go to A&E to prevent permanent damage.
Find out about primary biliary cholangitis (primary biliary cirrhosis), which is a type of long-term liver disease where the bile ducts in the liver become damaged.
Progressive supranuclear palsy (PSP) is a rare neurological condition that can cause problems with balance, movement, vision, speech and swallowing.
Read more about prostate cancer, including symptoms and possible treatments.
Psoriasis is a skin condition that causes flaky patches of skin, which form silvery-white or grey scales.
Read more about a pulmonary embolism, which is when a blood clot blocks a blood vessel in your lungs. It can be life-threatening if not treated quickly.
Pulmonary hypertension is high blood pressure in the blood vessels that supply the lungs. It's a serious condition that can damage the right side of the heart.
Find out about plantar fasciitis, including the causes, the symptoms and how to ease them, when to get medical help and treatments from a specialist.
Find out about common causes of pain in the top of your foot (ball, arch or sole) and how you might treat it.
Find out about common causes of pain in the bottom of your foot (ball, arch or sole) and how you might treat it.
Find out about pain in the ball of your foot, which is known as metatarsalgia, common causes and how you might treat it.
Find out about what to do about pain in the palm of your hand, when to get help and the common causes.
Read more about what to do about pain in the back of your hand, when to get help and the common causes.
Find out about pancreatic cancer, including the symptoms, causes, tests, treatments, and where to get support.
Find out about penile cancer, a rare type of cancer that mostly affects the skin of the penis.
Find out about Peyronie's disease, a condition that causes your penis to curve when it’s erect. Find out about the symptoms, when to get medical help and treatment.
Find out about lumps and spots on the penis, including what can cause them and when to get medical advice.
Find out about the PSA test, including why it is done and how you need to prepare.
All you need to know about pregnancy, labour and birth including trying to get pregnant, foods to avoid, antenatal care and how to keep well in pregnancy.
Read about psychosis, a mental health problem that causes people to perceive or interpret things differently from those around them.
Information on postpartum psychosis (psychosis after childbirth), with links to other useful resources.
NHS information about personality disorders, including the main symptoms and treatments.
Read about psychotic depression, a severe form of depression where people experience the usual symptoms of depression, plus delusions and hallucinations.
A phobia is an overwhelming and debilitating fear of an object, place, situation, feeling or animal.
Postnatal depression is a type of depression that many parents experience after having a baby. It's a common problem, affecting more than 1 in every 10 women within a year of giving birth.
Panic disorder is where you keep having panic attacks, often for no obvious reason. Includes symptoms, treatments and self-help tips.
Post-traumatic stress disorder (PTSD) is an anxiety disorder caused by very stressful, frightening or distressing events.
Read about the difference between psychiatry and psychology, and find out about the conditions psychiatrists may treat, how to get an appointment, and what your appointments may involve.
The progestogen-only pill, also called the mini pill, is a type of hormonal contraception.
NHS information about the pneumococcal vaccine, including what the vaccine helps protect against, who should have it, how to get it and side effects.