Major
Lithium × naproxen
Psycholeptics. Lithium×NSAID, propionic acid derivative
Mechanism
NSAIDs reduce renal lithium clearance via prostaglandin-dependent renal blood flow blockade. Lithium plasma levels rise 1.5- to 2-fold with toxicity risk.
Symptoms
Tremor, muscle twitching, nausea, diarrhoea, confusion, ataxia. Symptoms emerge when serum lithium exceeds 1.2 mmol/L.
Management
Avoid prolonged combination. If naproxen is needed for a short course, reduce lithium by 25–30% and check lithium level at 5–7 days. For chronic analgesia: paracetamol or celecoxib (with lithium monitoring).
Check the full regimen, not just this pair
Opens the checker with these two drugs prefilled. Add the rest of the regimen and recompute additive risks.