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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.
H
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Haemagglutination
clumping of red blood cells -
Haemagglutinins
<virus> proteins that make red blood cells clump together -
Haematological
<of> <related to> blood -
Haematoma
a collection of blood under the skin -
Haematopoietic (blood) stem cell transplantation
a procedure where the patient's bone marrow is <cleared of cells and> replaced <by stem cells> <from a donor> <with the patient's own stem cells> to form new bone marrow <that produces healthy cells> -
Haematopoietic progenitor cells
see stem cells -
Haematuria
blood in the urine -
Haemodialysis
procedure for removing waste products from the blood <used in patients with kidney disease> <using a blood filtration machine> -
Haemoglobin
the protein in red blood cells that carries oxygen around the body -
Haemolytic anaemia
see anaemia, haemolytic -
Haemophilia A
an inherited bleeding disorder caused by lack of factor VIII -
Haemophilia B
an inherited bleeding disorder caused by lack of factor IX -
Haemoptysis
coughing blood -
Haemorrhage
bleeding -
Haemorrhagic stroke
see stroke, haemorrhagic -
Haemostasis
stopping bleeding -
Hallucination
seeing, hearing or feeling things that are not there -
Hand foot syndrome
rash and numbness on the palms and soles -
Hay fever
inflammation of the nasal passages caused by an allergy to pollen -
Heart failure
when the heart does not pump blood as well as it should <with shortness of breath, tiredness and ankle swelling> -
Heart failure, congestive
when the heart does not pump blood as well as it should <with build-up of fluid around the heart> <causing shortness of breath, tiredness and ankle swelling> -
Heart failure, decompensated
when the heart is working less and less well -
Hepatic
liver -
Hepatic encephalopathy
see encephalopathy, hepatic -
Hepatitis
inflammation of the liver -
Hepatitis, cholestatic
build-up of bile leading to inflammation of the liver -
Hepatomegaly
enlarged liver -
HER2
a protein involved in the growth of certain types of breast cancer -
Herpes simplex
viral infection of the mouth (such as cold sores) or the genitals -
Herpes zoster
see shingles -
Hirsutism
excessive hair <in parts where there is usually very little or no hair> -
Histamine
a substance in the body that causes allergic symptoms -
HMG-CoA reductase
an enzyme in the liver that is needed to make cholesterol -
Hodgkin’s lymphoma
see lymphoma -
Hormone
a substance <released by a gland> that circulates in the blood and helps body organs to work in specific ways -
Hormone treatment
treatment that blocks or increases the effects of specific hormones -
Hyperaemia
increased blood flow -
Hyperaemia, ocular
red eye -
Hyperammonaemia
high blood levels of ammonia -
Hyperammonaemic encephalopathy
see encephalopathy, hyperammonaemic -
Hyperbilirubinaemia
high blood levels of bilirubin<, a breakdown product of red blood cells, which can cause yellowing of the skin and eyes><, indicating liver problems> -
Hypercalcaemia
high blood calcium levels -
Hypercalciuria
high calcium levels in the urine -
Hyperchloraemic acidosis
excess acid in the blood caused by too much chloride -
Hypercholesteraemia
high blood cholesterol levels -
Hypercholesterolaemia, primary
high blood cholesterol levels that have no identifiable cause -
Hyperglycaemia
high blood glucose levels -
Hyperglycaemic coma
coma caused by too much blood glucose -
Hyperhidrosis
excessive sweating -
Hyperkalaemia
high blood potassium levels <which can cause tiredness, muscle weakness, feeling sick and heart rhythm disturbances> -
Hyperlactataemia
high blood levels of lactic acid -
Hyperlipidaemia
high blood levels of fat -
Hypernatraemia
high blood sodium levels <which can cause thirst, tiredness, confusion and seizures> -
Hyperparathyroidism
when the parathyroid glands produce too much parathyroid hormone, which raises calcium levels in the blood <and can lead to bone and muscle pain, dehydration, and fragile bones> -
Hyperphosphataemia
high blood phosphate levels -
Hyperplasia
enlargement of an organ or body tissue <caused by increased cell division> -
Hypersensitive
allergic -
Hypersensitivity
allergic reactions -
Hypersensitivity reaction, acute systemic
allergic reaction with widespread effects such as shortness of breath, skin rashes and low blood pressure -
Hypertension
high blood pressure -
Hypertension, ocular
raised pressure in the eye -
Hypertensive crisis
sudden, dangerously high blood pressure -
Hyperthermia
high body temperature -
Hyperthyroidism
an overactive thyroid gland <which can cause weight loss, nervousness, rapid or irregular heartbeart and tiredness> -
Hypertonia
muscle tension -
Hypertriglyceridaemia
high blood levels of triglycerides, a type of fat -
Hypertrophic granulation
see granulation, hypertrophic -
Hypertrophy
excessive growth;
increase in the number or size of cells -
Hyperuricaemia
high blood levels of uric acid -
Hypervolaemic
when the amount of water in the body is higher than normal -
Hypoacusis
hearing loss -
Hypoaesthesia
reduced sensation to touch, pain and temperature -
Hypoalbuminaemia
low levels of albumin, a blood protein -
Hypocalcaemia
low blood calcium levels -
Hypoglycaemia
low blood glucose levels -
Hypokalaemia
low blood potassium levels <which can cause weakness, muscle cramps, tingling and heart rhythm disturbance> -
Hypomagnesaemia
low blood magnesium levels -
Hypomania
feeling excited and overactive -
Hyponatraemia
low blood sodium levels <which can cause headache, tiredness, fits and coma> -
Hypophosphataemia
low blood levels of phosphates -
Hypoplasia
incomplete development of an organ or tissue -
Hypoproteinaemia
low blood protein levels -
Hypotension
low blood pressure -
Hypotension, orthostatic
see hypotension, postural -
Hypotension, postural
feeling dizzy or lightheaded on standing or sitting up because of a drop in blood pressure -
Hypothalamus
a region of the brain -
Hypothyroidism
an underactive thyroid gland <with tiredness, weight gain, and skin and hair changes> -
Hypotonia
reduced muscle strength or tone -
Hypoxia
lack of oxygen in body tissues