Pain

Clinical approach

Pain is subjective and culturally shaped. The patient is the best judge of its intensity when they can communicate, so pain assessment should be recorded and repeated like a vital sign.

Effective treatment depends on identifying the pain type, severity, cause, functional impact, and response to treatment. Treat the cause whenever possible, but do not withhold symptomatic relief while investigating.

Use oral treatment whenever possible, prescribe at fixed intervals for ongoing pain, anticipate painful procedures, and combine medicines from different classes when appropriate.

History and clinical examination

• Ask location, onset, duration, progression, severity, character, radiation, pattern, relation to movement/care/night/rest, aggravating factors, relieving factors, trauma, fever, weight loss, pregnancy, previous episodes, comorbidities, and medicines already taken.
• Examine the painful organ or region and look systematically for the underlying disease, not only for the pain itself.
• Review associated signs such as fever, pallor, shock, neurological deficit, abdominal guarding, bone or joint swelling, respiratory distress, urinary retention, rash, weight loss, or bleeding.
• Red flags include chest pain, severe abdominal pain, sudden severe headache, pain with shock, severe trauma, neurological deficit, pregnancy, fever with stiff neck, severe swelling, or rapidly worsening pain.

Pain classification

Pain evaluation scales

• FLACC total score is 0 to 10: 0 to 3 suggests mild pain, 4 to 7 moderate pain, and 7 to 10 severe pain.
• A neonatal facial score of 2 or more indicates significant pain requiring analgesic treatment.

Nociceptive pain treatment ladder

Start at the level expected to control the pain, not necessarily at level 1. For example, a fractured femur should receive strong analgesia from the beginning.

• Multimodal analgesia is often more effective than increasing a single medicine alone.
• Prescribe regular dosing for continuous pain and rescue dosing only within a monitored plan.

Opioid safety and adverse effects

• Morphine is effective for many types of severe pain and should not be avoided when clearly indicated, but dose increases must be gradual and monitored.
• Drowsiness usually precedes opioid respiratory depression; monitor respiratory rate, sedation, oxygenation, pain score, nausea, vomiting, constipation, and urine retention.
• Respiratory rate should remain at or above about 25/minute in children 1 to 12 months, 20/minute in children 1 to 2 years, 15/minute in children 2 to 5 years, and 10/minute in older children and adults.
• Treat respiratory depression promptly with stimulation, oxygen, airway support, bag-mask ventilation if needed, and naloxone boluses repeated until respiratory rate and excessive drowsiness improve.
• Morphine, tramadol, and codeine should not be combined with each other. Avoid combining agonist opioids with buprenorphine, nalbuphine, or pentazocine because analgesia can be reduced or withdrawal/complications may occur.
• Morphine and codeine cause constipation; prescribe lactulose if opioid treatment continues longer than 48 hours. If stools remain soft but constipation persists, a stimulant laxative such as bisacodyl may be preferred.
• Nausea and vomiting are common at the start of opioid treatment. Children may receive ondansetron where appropriate; adults may receive haloperidol or metoclopramide, but the two should not be combined.

Pregnancy and breastfeeding

Neuropathic, mixed, and chronic pain

• Common analgesics are often insufficient for neuropathic pain. Treatment may require centrally acting medicines such as amitriptyline with carbamazepine according to local protocol and patient risk.
• Amitriptyline in adults is commonly introduced at bedtime and increased weekly according to response and tolerance; older adults usually need lower doses.
• Carbamazepine can be teratogenic and should be avoided in pregnancy; in women of childbearing potential, use only with effective contraception and careful risk-benefit review.
• Mixed pain with a major nociceptive component, such as cancer or advanced HIV disease, may combine morphine with antidepressant and antiseizure adjuvant medicines.
• Chronic pain often needs a multidisciplinary plan: medical treatment, physiotherapy, psychological support, nursing care, function goals, self-management, and regular review.
• Co-analgesics such as antispasmodics, muscle relaxants, anxiolytics, corticosteroids, and local anaesthetics may be useful when matched to the pain mechanism.

Complications, prevention, and follow-up

• Complications of untreated pain include immobility, poor sleep, poor feeding, delayed recovery, chronic pain sensitisation, psychological distress, and avoidance of necessary care.
• Complications of treatment include NSAID-related bleeding or renal injury, paracetamol overdose, opioid sedation or respiratory depression, constipation, nausea, dependence risk, falls, and drug interactions.
• Prevent procedure-related pain by prescribing analgesia before painful care, using local anaesthesia when appropriate, and preparing children and adults honestly and calmly.
• Reassess pain score, function, adverse effects, and cause after treatment. Escalate if pain remains severe, new red flags appear, or the cause is not controlled.
• Refer urgently for pain suggesting myocardial infarction, surgical abdomen, meningitis, compartment syndrome, ectopic pregnancy, severe trauma, spinal cord compression, acute glaucoma, severe infection, or uncontrolled cancer-related pain.