Acute vs Chronic
In medical terms, ‘acute’ refers to sudden onset disease which lasts for short duration and severe in nature, whereas Chronic illness lasts for months, usually more than 3 months. Chronic illness can be a continuation of an acute illness, when an acute illness not resolved.
In Medicine, the acute is the word used to refer the sudden onset disease which lasts for short duration. The duration may vary from hours to days. Most of the time acute illnesses are severe in nature. Acute illness may subside or can continue as chronic illness. The word sub acute also used in medicine (Sub acute bacterial endo carditis). Some diseases have only acute conditions (Myocardial infarction i.e. Heart attack). Some have acute and chronic conditions (Ex Bronchial Asthma).
Chronic illness means the illness lasts for months, usually more than 3 months. Chronic illness can be a continuation of an acute illness, when an acute illness not resolved. Chronic illness can be a gradual onset and slow progressive disease. (Ex: Chronic osteo arthritis).
Diabetes mellitus, Hypertension are the common diseases that need lifelong treatment. In other words they are chronic diseases with chronic treatment. Bronchial asthma may be a chronic disease but need treatment continuously or when the symptoms get worse (acute exacerbation).
There are acute conditions which are life threatening. Example ruptured ectopic pregnancy, acute myocardial infarction, acute respiratory distress, Diabetic keto acidosis, acute severe asthma, perforated peptic ulcer disease. These conditions need immediate attention to save the life!
In general, patient with acute illness seek medical advice as the symptoms usually are severe in nature.
In chronic diseases, there is a tendency of neglecting symptoms as they are mild or asymptomatic.
Finally, the words acute and chronic are based on the time frame.