Acute pain is the normal, predicted physiological response to a noxious chemical, thermal or mechanical stimulus, and typically is associated with invasive procedures, trauma, and disease.
It is generally time-limited, and resolves over days to weeks. It can persist less than 3-6 months.

It results from activation of pain receptors (nociceptors) at the site of tissue damage. This type of pain generally accompanies surgery, traumatic injury, tissue damage, and inflammatory processes. Acute pain plays the vital role of providing a warning signal that something is wrong and needs further examination.
It can activate the sympathetic branch of the autonomic nervous system and produce such responses as hypertension, tachycardia, diaphoresis, shallow respiration, restlessness, facial grimacing, guarding behavior, pallor, and pupil dilation.
Although pain in response to tissue damage is a normal phenomenon, it may be associated with significant, unnecessary physical, psychological, and emotional distress. Inadequately controlled acute pain can lead to clinical complications and be a factor in the development of chronic pain.

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Adapted from Medscape Drugs & Diseases. Acute pain: assessment and treatment. Available at http://www.medscape.com/viewarticle/735034. Accessed February 15, 2016. To view the entire article and all other content on the Medscape Drugs & Diseases site, a free, one-time registration is required.