Nervous system
Absence seizures
Non-infectious · Chronic
Brief episodes of blank staring caused by sudden bursts of abnormal brain activity, most common in children.
GeoMed · Disease encyclopedia
Disease encyclopedia
Causes, symptoms, diagnosis, treatment approaches and prevention for common conditions. Browse A–Z, by body system, or search.
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Disease encyclopedia
Nervous system
Mental health
Adjustment disorder
Non-infectious · Acute
An emotional or behavioural reaction to a stressful life event that is stronger or lasts longer than expected and affects daily life.
Endocrine system
Adrenal insufficiency (secondary)
Non-infectious · Chronic
A lack of cortisol caused by the pituitary or hypothalamus not stimulating the adrenal glands, often after long-term steroid use.
Nervous system
African trypanosomiasis (sleeping sickness)
Infectious · Chronic
A parasitic infection spread by tsetse flies in sub-Saharan Africa, which can invade the brain and is fatal without treatment.
Ear, nose and throat
Age-related hearing loss
Non-infectious · Chronic
The gradual loss of hearing in both ears that happens with ageing, especially for high-pitched sounds.
Eyes and vision
Age-related macular degeneration
Non-infectious · Chronic
A common eye condition in older adults that damages the macula, causing loss of central vision.
Digestive system
Alcoholic liver disease
Non-infectious · Chronic
Liver damage caused by drinking too much alcohol over time, progressing from fatty liver to hepatitis and cirrhosis.
Digestive system
Alcohol use disorder
Non-infectious · Chronic
A medical condition in which a person has difficulty controlling their drinking despite harm to their health, relationships or responsibilities.
Nervous system
Alcohol withdrawal
Non-infectious · Acute
Symptoms that occur when someone who is physically dependent on alcohol suddenly stops or cuts down, ranging from shakiness to life-threatening seizures and delirium.
Immune system
Allergic conjunctivitis
Non-infectious · Acute or chronic
Inflammation of the clear lining of the eye caused by an allergic reaction, leading to itchy, red, watery eyes.
Immune system
Allergic rhinitis (hay fever)
Non-infectious · Chronic
An allergic reaction in the nose causing sneezing, a runny or blocked nose and itching, often triggered by pollen or dust mites.
Immune system
Alopecia areata
Non-infectious · Acute or chronic
An autoimmune condition in which the immune system attacks hair follicles, causing round patches of hair loss.
Skin (integumentary system)
Alopecia (telogen effluvium)
Non-infectious · Acute
Temporary, widespread hair shedding that starts a few months after a stress to the body, such as illness, childbirth or crash dieting.
Respiratory system
Alpha-1 antitrypsin deficiency
Non-infectious · Chronic
An inherited condition in which low levels of a protective protein lead to lung damage (emphysema) and sometimes liver disease.
Urinary system
Alport syndrome
Non-infectious · Chronic
An inherited condition affecting a type of collagen in the kidneys, ears and eyes, causing kidney disease and hearing loss.
Nervous system
Alzheimer's disease
Non-infectious · Chronic
The most common cause of dementia, a progressive brain disease that gradually affects memory, thinking and daily abilities.
Eyes and vision
Amblyopia (lazy eye)
Non-infectious · Chronic
Reduced vision in one eye that develops in childhood because the brain and eye are not working together properly.
Endocrine system
Amenorrhoea
Non-infectious · Chronic
Absence of periods, either because they never started by age 15 or because they stopped for three months or more.