Acute pain is short‐term pain of less than 12 weeks’ duration (British Pain Society [29]). Acute pain serves a purpose by alerting the individual to a problem and acting as a warning of tissue damage or potential tissue damage. If left untreated, it may result in severe consequences; for example, not seeking help for acute abdominal pain may result in an emergency, such as appendicitis progressing to peritonitis. Acute pain occurs in response to any type of injury to the body and resolves when the injury heals.

Common causes of acute pain include:

Chronic pain is defined as persistent or recurrent pain lasting longer than 12 weeks (Treede et al. [179]). It is often associated with major changes in personality, lifestyle and functional ability (Orenius et al. [135]).

Chronic pain disorders can be categorized into the following seven groups (Treede et al. [179]):

Chronic pain is often associated with significant emotional distress and functional disability. It can be associated with many different types of disease processes and tissue injuries. Pain has a significant impact on individuals and their family, affecting mood, sleep, mobility, role within the family, ability to work and other aspects of life (NICE [127]).

In many instances of visceral pain, the pain is either perceived deep within the skin that overlies the affected organ or experienced at a location distant from the site of the painful stimulus or organ; the latter is known as referred pain (Tortora and Derrickson [177]). One explanation for the phenomenon of referred pain is that the visceral organ involved and the area to which the pain is referred are served by the same segment of the spinal cord, and the sensory fibres enter the spinal cord at the same level. Referred pain is presumed to occur because the information from multiple nociceptor afferents converges onto individual spinothalamic tract neurons, and the brain therefore interprets the information coming from visceral receptors as having arisen from receptors on the body surface, since this is where nociceptive stimuli originate most frequently. Examples of referred pain include pain in the left arm during a myocardial infarction, pain from pancreatic pathology experienced as pain in the back, and pain from irritation of the diaphragm experienced as shoulder tip pain (see Figure 10.3).

Pain is a common symptom in patients with cancer (Chapman [36]). Causes of cancer pain can be multifactorial and often are related to the effects of cancer treatments such as surgery, radiotherapy, chemotherapy, hormone therapy or immunotherapy. In some instances, pain can be caused by the cancer itself, such as in patients with bone metastases or where the cancer has caused injury to nerves. Cancer pain has been reported as being present in a third of patients undergoing active anti‐cancer treatment with a curative intent. It has also been suggested that patients who have treatment with curative intent or for palliation report pain prevalence rates of 39.3% after curative treatment, 55.0% during anti‐cancer treatment, and 66.4% in advanced, metastatic or terminal disease (van den Beuken‐van Everdingen et al. [184]). Cancer pain can be both acute and chronic and requires careful assessment and attention to detail, including a detailed history of previously tried medications and responses to these pharmacological interventions. Assessment, the treatment plan and reviews are key in the management of cancer pain, particularly as the nature and severity of pain can change rapidly in response to treatment or progression of the cancer itself. For the comprehensive management of cancer pain, see the chapter on pain assessment and management in The Royal Marsden Manual of Cancer Nursing Procedures (Lister et al. [97]).