On Monday, 12 January 2026, between 07:00 and 10:00 CET (Amsterdam time), this website will be unavailable due to scheduled maintenance.
This resource focuses on side effects and other terms used in medicines information and assessments of medicines. It does not include terms that are used only rarely, nor does it cover most disease states or technical terms.
How to use EMA’s medical terms simplifier
- You can search for a term or click on a letter below to see terms beginning with that letter.
- Each entry contains a short description. For some, a longer or alternative description is available by selecting the term.
- We use ‘< >’ to indicate alternative or optional wording.
EMA’s medical terms simplifier will be updated periodically. For comments or suggestions, you can use our Medical terms simplifier comments form.
P
-
Paediatrician
doctor specialised in the treatment of children -
Paget's disease
a disease involving bone destruction and regrowth, which causes deformity -
Pain, neuropathic
pain due to nerve damage -
Palliative
relieving symptoms -
Palliative care
treatment of the symptoms of a disease that is not intended to lead to cure -
Palmar-plantar erythrodysaesthesia syndrome
see hand foot syndrome -
Palpitations
a forceful heartbeat that may be rapid or irregular -
Palsy
paralysis with weakness and shaking -
Pancreatitis
inflammation of the pancreas <causing severe pain in the belly and back> -
Pancytopenia
<low levels of blood cells> / <low levels of all types of blood cells <including platelets>> -
Pandemic
when a disease spreads to a large number of people in many countries worldwide -
Papillomaviruses
viruses that cause warts and abnormal tissue growth -
Paraesthesia
sensations like numbness, tingling, pins and needles -
Parathyroid glands
glands that secrete the hormone that controls blood calcium levels -
Parkinsonism
effects similar to Parkinson’s disease such as shaking, muscle stiffness and slow movement -
Parkinson’s disease
a progressive brain disease that causes shaking and muscle stiffness and slows movement -
Paronychia
nail bed infection -
Partial response
[used in cancer trials] <shrinkage of the tumour><decrease in the extent of the cancer> after treatment -
Partial<-onset> seizure <with <or without> secondary generalisation>
see seizure, partial<-onset> <with <or without> secondary generalisation> -
Patent ductus arteriosus
see ductus arteriosus, patent -
Patient-reported outcome
[used in cancer trials] report directly from the patient of how well they are doing -
Patient-year
the equivalent of one patient taking the medicine for one year -
Peak expiratory flow
the maximum speed a person can breathe out -
Pedal arteries
arteries that supply blood to the feet -
PEG (percutaneous endoscopic gastrostomy)
a feeding tube inserted through the skin into the stomach; see gastrostomy -
Pegylated
attached to a chemical called polyethylene glycol -
Pegylated liposomes
tiny fatty spheres that are <coated with> <attached to> a chemical called polyethylene glycol -
Pelvic
lower abdominal -
Pelvic inflammatory disease
a type of infection of the upper part of the female genital tract -
Peptic ulcer disease
ulcers in the stomach or the duodenum -
Peptide
a short chain of amino acids -
Percutaneous coronary intervention
a procedure that unblocks blood vessels of the heart to restore its blood supply -
-
Percutaneous transluminal coronary angiography (PTCA)
surgical procedure that is used to unblock narrowed coronary arteries -
Perennial
occurs throughout the year -
Performance status
a rating of how well a patient is -
Perfusion
blood circulation <through an organ> -
Pericardial disease
disease of the membrane around the heart -
Pericarditis
inflammation of the membrane around the heart -
Periocular infections
infections around the eyes -
Periorbital oedema
see oedema, periorbital -
Peripheral arterial disease
see artery disease, peripheral -
Peripheral motor neuropathy
see neuropathy, peripheral motor -
Peripheral neuropathy
see neuropathy, peripheral -
Peripheral oedema
see oedema, peripheral -
Peritoneal cavity
The area of the belly that contains the intestines -
Peritoneal dialysis
see dialysis, peritoneal -
Peritoneum
the membrane that forms the lining of the abdominal (belly) cavity -
Pertussis
whooping cough -
Petechiae
tiny blood spots under the skin -
Phaeochromocytoma
a tumour of the adrenal gland -
Phagocytes
specialised ‘scavenger’ cells of the immune system -
Pharmacodynamics
a medicine’s effects in the body -
Pharmacokinetics
how a medicine is absorbed, modified and removed from the body -
Pharyngitis
sore throat -
Philadelphia chromosome positive (Ph+)
when some of the patient's genes have rearranged themselves to form a special chromosome called the Philadelphia chromosome. -
Phlebitis
inflammation of a vein -
Phlebotomy
removal of some of the blood from the body -
Phosphenes (luminous phenomena)
a temporary brightness in the field of vision -
Photodynamic therapy
treatment in which a medicine is ‘switched on’ by <a special type of> light -
Photophobia
abnormal sensitivity of the eyes to light -
Photopsia
flashes of light in the field of vision -
Photosensitising agent
a medicine ‘switched on’ by <a special type of> light <and used for photodynamic therapy> -
Photosensitivity reactions
sunburn-like reactions (following exposure to light) -
Pigmentation
colouring of the skin, hair and eyes -
Pituitary gland
a gland <at the base of the brain> that controls many other hormone-producing glands in the body -
Placebo
dummy treatment -
Plaque psoriasis
see psoriasis -
Plasma
the liquid part of the blood; the part of the blood left when the blood cells are removed -
Plasma exchange
a procedure to remove <unwanted> <substances> <antibodies> from plasma (the liquid part of the blood) <by replacing the patient’s plasma with plasma from a donor> -
Plasmapheresis
see plasma exchange -
Plasmin
an enzyme that breaks up clots <and helps restore the normal blood flow to the heart> -
Platelet aggregation
platelets clumping together <which can lead to a blood clot> -
Platelets
components that help the blood to clot -
Pleural effusion
fluid around the lungs -
Pleuritic pain
a type of chest pain -
Pneumonia
infection of the lungs -
Pneumonitis
inflammation in the lungs <causing shortness of breath and cough> -
Pneumonitis, hypersensitivity
inflammation in the lungs due to an allergy <causing shortness of breath and cough> -
Poliomyelitis
polio -
Pollakiuria
abnormally frequent urination -
Polyuria
increase in urine production -
Porphyria
an inability to break down chemicals called porphyrins -
Portal vein
vein leading to the liver -
Post-herpetic neuralgia (PHN)
see neuralgia, post-herpetic -
Posterior reversible encephalopathy syndrome
brain swelling with <usually temporary effects such as> headache, changes in vision, reduced consciousness and seizures -
Postmenopausal women
women who have been through the menopause -
Postpartum
after childbirth -
Postural hypotension
see hypotension, postural -
Precancerous lesions
abnormal cells that could develop into cancer -
Preclinical studies
laboratory studies -
Preprandially
before meals -
PRES
see posterior reversible encephalopathy syndrome -
Preterm
premature -
Prevalence
the number of people with the disease -
Primary hypercholesterolaemia
see hypercholesterolaemia, primary -
Primary immunodeficiency syndrome
see immunodeficiency disorder, primary -
Primary insomnia
see insomnia, primary -
Proctalgia
anal pain -
Prodrug
a medicine that is converted to an active form in the body -
Progression (disease)
[used in cancer trials] getting worse -
Progression-free survival
[used in cancer trials] how long patients live without their disease getting worse -
Progressive multifocal leukoencephalopathy (PML)
a rare but serious <viral> brain infection <with symptoms similar to those of a multiple sclerosis attack> -
Prolonged release
the active substance is released slowly <from the tablet> over a few <weeks/ days/hours> <after being injected> -
Prophylaxis
prevention -
Prostate
gland that produces fluid that nourishes and carries sperm -
Proteasome
a system within cells that breaks down proteins when they are no longer needed -
Proteinuria
excess protein in the urine -
Pruritus
itching -
Psoriasis
<a> <an inflammatory> disease causing red, scaly patches on the skin -
Psoriatic arthritis
a disease, causing inflammation in the joints in combination with psoriasis -
Psychomotor hyperactivity
restlessness -
Psychosis
altered sense of reality -
Pulmonary (arterial) hypertension
high blood pressure in <the arteries of> the lungs -
Pulmonary artery
the blood vessel that leads from the heart to the lungs -
Pulmonary embolism
clot in a blood vessel in the lungs <which can cause chest pain, breathlessness and fainting> -
Pulmonary fibrosis
see fibrosis, pulmonary -
Pulmonary nodule
a small <area of damage> <lump> in the lungs -
Punctate keratitis
spots of inflammation in the cornea -
Pure red cell aplasia
a condition in which no red blood cells are produced -
Purpura
purple patches like bruising -
Pustulation
blisters -
Pyelonephritis
kidney infection -
Pyrexia
fever