Nsaids

What NSAIDs do (core concepts)

• NSAIDs reduce pain, inflammation, and fever by inhibiting cyclo-oxygenase (COX) enzymes and therefore prostaglandin production.
• Analgesic effect is opioid-sparing (often reduces opioid requirement and opioid side-effects).
• COX-1 is involved in gastric protection, platelet function, and renal blood flow, COX-2 is more inducible in inflammation (COX-2 selective drugs tend to cause less gastric irritation but still have renal and cardiovascular risks).
• They are best used as part of multimodal analgesia (e.g., paracetamol + NSAID ± regional anaesthesia ± opioid as needed).

Common peri-operative NSAIDs in the UK (examples)

• Ibuprofen: common oral NSAID for ward/discharge, check asthma/renal/GI risk.
• Diclofenac: oral/PR, useful but higher cardiovascular risk signal than some alternatives, avoid in established ischaemic heart disease/heart failure.
• Naproxen: longer acting, often considered lower cardiovascular risk than diclofenac (still GI/renal risks).
• Ketorolac: potent, often used short-term, higher risk of renal impairment and bleeding—use carefully and avoid in high-risk patients.
• COX-2 selective (e.g., celecoxib/etoricoxib): less platelet effect and less GI ulceration than non-selective NSAIDs, but renal effects still occur, consider cardiovascular risk.

When to consider an NSAID (typical “first time” scenarios)

• Post-op pain where inflammation contributes (orthopaedics, dental, soft tissue surgery) and there are no major contraindications.
• When you want opioid-sparing in patients prone to nausea, ileus, sedation, or respiratory depression (but still check renal/GI/bleeding risk).
• Day-case pathways: a single peri-operative dose can improve comfort and reduce opioid need at home (ensure clear discharge advice).
• Renal colic: NSAIDs can be very effective (reduce ureteric spasm/inflammation) but avoid if AKI/dehydrated/sepsis.

Pre-op checklist before prescribing/administering

• Kidneys/volume status: recent creatinine/eGFR if available, avoid if AKI, significant CKD, dehydration, sepsis, or hypotension.
• GI risk: history of peptic ulcer/upper GI bleed, consider PPI cover if NSAID essential and risk is moderate (follow local policy).
• Bleeding risk: active bleeding, high-risk surgery for bleeding, thrombocytopenia, coagulopathy, remember non-selective NSAIDs inhibit platelet function (COX-2 selective have minimal platelet effect).
• Asthma/NSAID sensitivity: ask about previous wheeze, facial swelling, or anaphylaxis after aspirin/ibuprofen/naproxen (avoid if suspected NSAID-exacerbated respiratory disease).
• Cardiovascular disease: avoid diclofenac in IHD, cerebrovascular disease, peripheral arterial disease, or heart failure, use lowest effective dose for shortest time.
• Pregnancy: avoid in 3rd trimester (risk of premature ductus arteriosus closure and oligohydramnios), seek senior/obstetric advice if unsure.
• Drug interactions: ACE inhibitor/ARB + diuretic + NSAID (“triple whammy”) increases AKI risk, anticoagulants/antiplatelets increase bleeding risk, lithium and methotrexate toxicity can be increased.

Dosing principles (safe practice)

• Use the lowest effective dose for the shortest time, reassess daily in inpatients.
• Avoid stacking multiple NSAIDs (e.g., ibuprofen plus diclofenac) — no added benefit, increased harm.
• If giving peri-operatively, document timing and agent clearly to avoid duplicate dosing on the ward.
• Consider gastroprotection (e.g., PPI) for higher GI-risk patients if NSAID is needed and not contraindicated (follow local guidance).

Adverse effects to recognise early

• Renal: reduced renal perfusion → AKI, fluid retention, higher risk with dehydration, sepsis, CKD, ACEi/ARB, diuretics, elderly.
• GI: dyspepsia, gastritis, ulceration, GI bleeding (may be occult).
• Bleeding: platelet inhibition (non-selective NSAIDs) can increase surgical bleeding, risk depends on procedure and patient factors.
• Respiratory/allergy: bronchospasm in susceptible asthma, urticaria/angioedema, anaphylaxis (rare).
• Cardiovascular: fluid retention, hypertension, worsening heart failure, thrombotic risk varies by agent and dose.

Practical peri-operative tips

• If hypotensive, septic, bleeding, or clearly volume-depleted: avoid NSAIDs and choose alternatives (paracetamol, regional techniques, opioids carefully).
• After major surgery with high AKI risk (e.g., major abdominal, vascular): be cautious—discuss with senior and consider delaying until stable and euvolaemic.
• If neuraxial/regional anaesthesia: NSAIDs alone are not usually a contraindication, but consider overall bleeding risk and other anticoagulants, follow local/regional guidelines.
• On discharge: advise to avoid additional over-the-counter NSAIDs and to stop and seek help if black stools, vomiting blood, severe abdominal pain, wheeze, facial swelling, or reduced urine output.

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