Attempt EGFR mutation assessment of tumour tissue. Interrupt treatment if worsening of resp symptoms eg, dyspnoea, cough & fever is experienced & confirmed ulcerative keratitis. Discontinue treatment in confirmed interstitial lung disease (ILD). Periodic liver function testing is recommended; discontinue if changes are severe. Impaired liver function due to cirrhosis. Avoid concomitant use w/ CYP3A4 inducers eg, phenytoin, carbamazepine, rifampicin, barbiturates or herbal prep containing St. John's wort/Hypericum perforatum
; warfarin; medicines that cause significant sustained elevation in gastric pH eg, proton-pump inhibitors & H2
-antagonists. Galactose intolerance, total lactase deficiency or glucose-galactose malabsorption. Severe or persistent diarrhoea, nausea, vomiting or anorexia that may indirectly lead to dehydration; signs & symptoms suggestive of keratitis. Increased risk of cerebral haemorrhage; GI perforation. May impair ability to drive & use machines. Moderate to severe hepatic impairment (Child-Pugh B or C). Renal impairment (CrCl ≤20 mL/min). Pregnancy. Contraindicated in breastfeeding. Paed patients <18 yr.