What is Acute, Subacute and Chronic?

Meaning of Acute

Acute is the medical term to describe the nature of a disease, sign, symptom or condition. It refers to an illness that is of a sudden onset or of a short duration. Acute can also be used as an adjective to describe a severe state of a condition. Often the term acute is used in contrast to the medical term chronic. In this case the difference lies between an illness that is short lived (acute) compared to an illness that is long term or persistent (chronic).

For example : Acute pain refers to pain that may have come on suddenly and is only present for a few days or even weeks. If the pain persists and is ongoing, it will be considered as chronic.

Meaning of Chronic

Chronic refers to any condition, disorder or disease that is ongoing. It is often thought to be permanent and while many chronic diseases are permanent, some can eventually resolve and disappear altogether. More correctly, chronic refers to a time frame of 3 months or more. However, this time frame may actually be shorter is some cases. Chronic conditions do not necessarily have to persist at all times. In other words the symptoms may not be present constantly. With some chronic conditions, the symptoms essentially come and go. This means it goes through active stages and periods of remission.

Does chronic mean it will worsen?

A common misconception about chronic is that it means the condition or disease worsens. This is inaccurate. There are chronic conditions that may never worsen or change at all and there some chronic conditions that can actually ease with time. Chronic is in reference to time. It is not a reflection on the progression or course of a condition or disease. Therefore the term ‘progressive’ is used to describe a condition that gets worse over time. Another important term is ‘gradual’ or ‘rapid’ which means that the speed at which the condition changes and is once again not a reference to whether a condition is acute or chronic.

Meaning of Subacute

Another medical term related to acute is subacute. This means that the symptom or illness is not yet chronic but has passed the acute phase. It may also indicate that the condition is not as severe as the acute stage. Acute, subacute and chronic may be used as a reference to time where acute refers to a condition that is present for less than 1 month, while subacute denotes a condition that is persisting for 1 to 3 months and chronic refers to any illness or ailment that is present for 3 months or longer.