Pain assessment starts with a simple but powerful step: asking the person in pain to describe what they feel. Because pain is subjective, there is no blood test or scan that directly measures it. Instead, clinicians and caregivers rely on a combination of self-report scales, structured questions, behavioral observation, and functional impact measures to build a complete picture. The right approach depends on who you’re assessing and whether they can communicate verbally.
Rating Scales: Putting a Number on Pain
The most common starting point is a numerical rating scale, or NRS. The person rates their pain from 0 to 10, where 0 means no pain and 10 means the most severe pain imaginable. It’s widely used in hospitals, clinics, and emergency rooms because it takes seconds and requires no equipment. Scores of 1 to 3 generally indicate mild pain, 4 to 6 moderate, and 7 to 10 severe.
A visual analog scale (VAS) works similarly but uses a 100-millimeter horizontal line printed on paper. One end represents no pain, the other represents the worst pain imaginable, and the person marks a point along the line. The distance from the left end, measured in millimeters, becomes the score. The VAS can capture subtler differences than a 0-to-10 scale, which makes it popular in research settings, but it requires a printed form and a ruler to score.
For children as young as three, the Wong-Baker FACES scale uses a row of six cartoon faces ranging from a broad smile (no pain) to a crying expression (worst pain). You point to each face, explain what it represents, and ask the child to pick the one that matches how they feel. It works well for anyone who struggles with abstract number scales, including some adults with communication difficulties.
Asking the Right Questions: The PQRST Framework
A number alone doesn’t tell you much about what’s actually happening. The PQRST mnemonic gives you a structured way to gather the details that matter.
- Provocation: What brings the pain on? Does a specific movement, activity, or position trigger it? Equally important: what relieves it?
- Quality: What does the pain feel like in the person’s own words? Let them describe it first. If they struggle, offer prompts: dull, sharp, stabbing, burning, pins and needles, or electric-shock-like.
- Region and radiation: Where exactly is the pain? Does it travel or spread to another area? Are there other symptoms alongside it, like nausea, shortness of breath, or tingling?
- Severity: How intense is it right now, on a 0-to-10 scale? How intense is it at its worst and its best?
- Timing: When did it start? Has it happened before? Is it constant, or does it come and go?
This framework is useful whether you’re a nurse triaging a patient, a caregiver calling a doctor’s office, or someone trying to organize your own symptoms before an appointment. The more specific your answers, the easier it is for a clinician to narrow down the cause.
Distinguishing Nerve Pain From Other Types
Not all pain works the same way. Pain from an injury, inflammation, or surgery typically feels like aching, throbbing, or soreness. Nerve pain feels distinctly different, and recognizing the difference changes how it’s treated.
A screening tool called the DN4 questionnaire identifies nerve pain by checking for a specific cluster of sensations. If the pain has a burning quality, feels like electric shocks, or is accompanied by painful cold, that points toward nerve involvement. So do tingling, pins and needles, numbness, or itching in the painful area. A score of 4 or more “yes” answers out of 10 items strongly suggests nerve pain. You can use these descriptors informally: if your pain matches several of them, mention that specifically to your provider, because it may point toward a nerve-related condition that responds to different treatments than standard painkillers.
Using Words to Describe Pain Quality
Pain researchers have identified two distinct categories of pain descriptors that predict different outcomes. Sensory descriptors capture the physical character of the pain: hot, burning, scalding, dull, sore, aching, tight, squeezing, crushing, cutting, stabbing, pricking, piercing, stinging, pulling, or jerking. Affective descriptors capture the emotional toll: annoyed, angry, furious, worried, fearful, terrified, gloomy, sad, or miserable.
This distinction matters practically. Sensory descriptors tend to predict physical disability, like difficulty walking or working. Affective descriptors tend to predict psychosocial impact, like withdrawal from relationships or worsening mood. When you assess pain, capturing both dimensions gives a fuller picture. A person who describes their back pain as “crushing” and “terrifying” is communicating something very different from someone who calls it “dull” and “annoying,” even if both rate it a 7 out of 10.
Measuring How Pain Affects Daily Life
Pain intensity alone doesn’t capture how much pain is actually disrupting someone’s life. The Brief Pain Inventory addresses this by asking how much pain has interfered with seven specific areas over the past week: general activity, mood, ability to walk, normal work, relationships with others, sleep, and enjoyment of life. Each area is rated from 0 (no interference) to 10 (complete interference).
This functional approach is especially useful for chronic pain, where the goal often shifts from eliminating pain entirely to reducing its grip on daily life. If someone’s pain score stays at a 5 but their sleep interference drops from 8 to 3, that’s meaningful progress. Tracking these domains over time also helps identify which parts of life are most affected, which can guide decisions about physical therapy, medication adjustments, or psychological support.
Assessing Pain in People Who Can’t Self-Report
When someone can’t describe their pain verbally, whether due to age, cognitive impairment, sedation, or intubation, behavioral observation becomes the primary tool.
For infants and young children, the FLACC scale scores five behaviors: facial expression, leg position, body activity, crying, and how easily the child can be consoled. Each category is scored from 0 to 2, giving a total between 0 and 10. A baby who is relaxed with a normal expression and no crying scores 0. One with a rigid body, clenched jaw, constant crying, and inability to be comforted scores closer to 10.
For older adults with advanced dementia, the PAINAD scale uses a similar approach with five observable behaviors. The American Geriatrics Society has identified six behavioral domains that signal pain in people with cognitive impairment: facial expressions like grimacing, vocalizations like groaning or moaning, body movements like rocking or guarding, changes in how the person interacts with others (increased aggression or withdrawal), disruptions to sleep or daily routines, and changes in mental state such as new confusion or agitation. Any sudden change in behavior in someone with dementia should prompt a pain assessment, because pain is one of the most common and most overlooked causes of behavioral changes in this population.
Vital Signs as Pain Indicators
It’s tempting to look at heart rate and blood pressure as objective proof of pain, but the relationship is weaker than most people assume. In critically ill patients, heart rate and breathing rate increase modestly during painful procedures like being turned in bed, but the changes are small. Systolic blood pressure shows the strongest association: in one study, it was about 27 mmHg higher in patients who reported pain compared to those who didn’t, and it correlated moderately with self-reported pain intensity.
Diastolic blood pressure and oxygen saturation showed no meaningful connection to pain. The takeaway is that vital signs can offer supporting clues, especially a notable spike in systolic blood pressure, but they’re not reliable enough to use as a standalone measure. Many things besides pain affect vital signs, including anxiety, medications, and underlying illness.
When Pain Becomes Chronic
Pain that persists beyond three months is classified as chronic. Under the current international classification system, chronic primary pain is defined as pain lasting longer than three months that causes significant emotional distress or functional disability and isn’t better explained by another diagnosis. This distinction matters because chronic pain often requires a different assessment approach than acute pain. The focus shifts from identifying and treating a specific injury to understanding how pain is affecting the whole person: their mobility, sleep, mood, work capacity, and social connections.
For chronic pain, combining a severity scale like the NRS with a functional tool like the Brief Pain Inventory and a qualitative framework like PQRST gives the most complete picture. Reassessing regularly, using the same tools each time, lets you track whether things are improving, stable, or getting worse in ways that a single snapshot never could.