1 Foundations of Pain and Pain Management
Learn how pain differs from nociception, how pain is processed and assessed, and how individualized management can address symptoms, function, and safety.
and
is a personal sensory and emotional experience associated with, or resembling that associated with, actual or potential tissue damage. Biology, emotions, expectations, past experiences, and social context can shape how is felt and affect daily life. A person’s report should be taken seriously even when an injury or imaging finding does not explain it.
is the nervous system’s detection and encoding of potentially harmful stimuli. It is not the same as the conscious experience of , and nociceptive activity alone cannot establish how much a person feels.
over time
may be described by its time course. Acute often begins with an injury, illness, or procedure and may serve as a warning signal. continues or recurs beyond the usual period of healing, often defined in clinical contexts as more than three months; it may remain after the original injury has healed.
These categories describe time, not cause. Acute can be severe, and persistent is not necessarily evidence of ongoing tissue damage.
How is processed
Nociceptive processing is often described in four overlapping stages. This is a simplified account: is not a simple meter of tissue damage, because the nervous system actively processes and modifies incoming information.
: Noxious mechanical, thermal, or chemical stimuli activate peripheral nociceptors, which convert the stimulus into nerve activity.
: Signals travel along sensory nerves to the spinal cord and are processed in the dorsal horn. They then ascend—especially through the anterolateral (spinothalamic) system—to the brainstem and thalamus, with onward connections to cortical and other brain regions.
: Signals can be amplified or dampened in the periphery, spinal cord, and brain. Descending pathways from the brain can inhibit or facilitate spinal .
: Brain networks integrate sensory input with attention, emotion, memory, expectations, and context, producing the personal experience of .
mechanisms
mechanisms can overlap in one person. These categories help guide assessment and treatment; they are not mutually exclusive boxes.
arises when nociceptors respond to actual or threatened damage to non-neural tissue. Somatic comes from skin, muscles, bones, or joints; visceral comes from internal organs and may be diffuse or referred. Examples include a sprain and some abdominal .
is caused by a lesion or disease of the somatosensory nervous system. Burning, electric-shock-like , tingling, or from normally nonpainful touch may occur. Examples include some diabetic neuropathy and postherpetic neuralgia.
arises from altered when there is no clear evidence that tissue damage or a demonstrable somatosensory-system lesion fully accounts for the . It can occur alongside other mechanisms.
Mechanism-based descriptions do not replace an individual assessment. Consider symptoms, history, examination, function, and possible underlying cause.
Assessing and its impact
is more than recording a number. When a person can communicate, self-report is central. Ask about the ’s location, onset, duration, and pattern—for example, whether it is constant, intermittent, or changing. Ask about its quality, such as aching, sharp, burning, or shooting, and what worsens or eases it.
Use an appropriate self-report scale for severity, then ask how affects sleep, mobility, mood, work, and valued activities. Consider relevant health conditions, medications, prior treatments, stressors, and the person’s goals and preferences. A score alone does not show the impact on daily life or whether treatment supports meaningful goals.
For someone who cannot reliably self-report, use appropriate behavioral or observational tools and information from caregivers. Difficulty communicating does not rule out . After treatment, reassess both relief and meaningful functional change.
Individualized management
combines approaches with different mechanisms to address and improve function. The plan is individualized according to likely mechanisms, health conditions, expected benefits and risks, preferences, access, and response over time.
Nonpharmacologic approaches: Options may include education, physical or occupational therapy, graded activity or exercise, psychological therapies, sleep support, and selected procedures or complementary approaches.
Nonopioid medications: Acetaminophen or a nonsteroidal anti-inflammatory drug (NSAID) may suit some . Acetaminophen overdose can severely injure the liver; check labels to avoid unintentionally combining multiple acetaminophen-containing products. NSAIDs can cause serious gastrointestinal, kidney, or cardiovascular harms in some people, so suitability should be assessed individually.
Adjuvant medications: Medicines developed for other purposes may help particular mechanisms. Selected antidepressants or anticonvulsants may be used for some conditions, and topical agents may be used for localized . Choice depends on the condition and patient-specific risks.
Opioids: Opioids may be appropriate in selected situations, but they are not a routine first-line approach for persistent . When considering them, discuss expected benefits, risks, alternatives, and goals, and monitor -related function and harms.
Medication safety and ongoing care
Combining treatments can sometimes improve benefit or reduce reliance on one medicine, but combinations can also increase harm. Opioids taken with alcohol or other central nervous system depressants—including benzodiazepines and some sedating medicines—can dangerously slow breathing.
Common opioid adverse effects include constipation, nausea, and sedation. An overdose can cause slowed or stopped breathing, inability to awaken, and death. If an overdose is suspected, give naloxone if available and call emergency services; naloxone does not replace emergency care.
Safe management is collaborative and ongoing. Set realistic goals, use the lowest-risk effective options, review medicines and possible interactions, and adjust the plan according to benefits and adverse effects. For opioid treatment, avoid sharing medicines and store them securely; discuss overdose risk and naloxone with a clinician when relevant.