• Common culprits: methotrexate, isoniazid, valproate, statins, nitrofurantoin, amiodarone
• Monitoring: LFTs routinely if on hepatotoxic agents (esp. methotrexate, statins)
• Patterns:
o Hepatocellular: ↑ ALT/AST (e.g. isoniazid, paracetamol)
o Cholestatic: ↑ ALP/GGT (e.g. co-amoxiclav)
o Mixed: e.g. phenytoin, sulfonamides
• Specifics:
o Methotrexate: fibrosis risk ↑ with alcohol; folic acid reduces risk
o Isoniazid: idiosyncratic hepatitis; check LFTs monthly
o Valproate: fatal hepatic failure (esp. in children); monitor during 6 months
o Statins: asymptomatic transaminitis; stop if ALT >3× ULN
o Paracetamol (overdose): centrilobular necrosis
• Common causes: azathioprine, valproate, furosemide, didanosine, steroids
• Presentation: epigastric pain radiating to back, ↑ amylase/lipase
• Diagnosis: 2 of 3 — abdominal pain, ↑ enzymes, imaging
• Exclude: gallstones, alcohol
• Drugs causing SIADH:
o SSRIs
o Carbamazepine
o Vincristine
o Cyclophosphamide
• Features: euvolaemic hyponatraemia, confusion, seizures
• Management: fluid restriction, stop culprit drug ± demeclocycline/tolvaptan
• Drugs:
o Tetracyclines
o Amiodarone
o Sulfonamides
o Thiazides
• Presentation: exaggerated sunburn-like rash on sun-exposed areas
• Causative drugs:
o Spironolactone (antiandrogenic)
o Digoxin (oestrogen-like structure)
o Cimetidine, Ketoconazole, Finasteride
• Mechanism: hormonal imbalance or oestrogenic effects
• Drug causes:
o Amiodarone (high iodine load; also causes hyperthyroidism)
o Lithium (inhibits thyroid hormone release)
o Carbimazole/PTU: overtreatment
• Monitoring: TFTs every 6 months during therapy
• Drugs: typical antipsychotics, metoclopramide
• EPS types:
o Acute dystonia: torticollis, oculogyric crisis
o Parkinsonism, akathisia, tardive dyskinesia
• Treatment:
o Acute dystonia: procyclidine, benztropine
o Stop causative drug
• Causative drugs:
o Non-selective beta-blockers (e.g. propranolol)
o NSAIDs (especially in aspirin-sensitive asthma)
• Avoid in patients with asthma or severe COPD
• Drugs worsening weakness:
o Aminoglycosides
o Fluoroquinolones
o Magnesium
o Beta-blockers
• Presentation: ptosis, diplopia, limb weakness, dyspnoea
• Offending agents:
o Amiodarone
o Methotrexate
o Nitrofurantoin
o Bleomycin
• Symptoms: dry cough, dyspnoea, crackles
• Investigations: CXR, HRCT, spirometry (restrictive defect)
• Causative drugs:
o Isoniazid (prevent with pyridoxine)
o Vincristine
o Amiodarone
o Cisplatin, Oxaliplatin
• Symptoms: glove-and-stocking numbness, paraesthesia
• Triggers: SSRI + MAOI, SNRI, triptans, linezolid, MDMA
• Features:
o CNS: agitation, confusion
o Neuromuscular: clonus, hyperreflexia, tremor
o Autonomic: fever, sweating, tachycardia
• Management:
o Stop serotonergic agents
o Supportive care
o Cyproheptadine (serotonin antagonist) in moderate/severe cases
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Author & Educational Disclaimer
Author:
Dr Phillip Cockrell BM FRCP DipClinEd
Dr Phillip Cockrell is a UK Consultant Physician in Internal Medicine, currently working at Queen Alexandra Hospital, Portsmouth University Hospitals NHS Trust. He has previously worked as a registrar across Intensive Care Medicine, Gastroenterology, Cardiology, Stroke Medicine, Acute Medicine, and Respiratory Medicine.
He has held senior leadership roles including Associate Clinical Director of the Acute Medical Unit, Clinical Director of Internal Medicine, and Chief of Medicine. Dr Cockrell has over 15 years’ experience in postgraduate medical education, having lectured extensively across the MRCP syllabus and contributed to MRCP revision teaching and course development.
Dr Cockrell holds a Bachelor of Medicine (BM), Fellowship of the Royal College of Physicians (FRCP), and a Diploma in Clinical Education (DipClinEd). His teaching approach is based on structured consolidation of complex medical topics to support efficient and effective revision for postgraduate examinations.
Purpose of this content:
The material on this page is intended solely for educational purposes to support revision for the MRCP (UK) Part 1 examination. It reflects examination-relevant principles of internal medicine and is designed to aid learning and pattern recognition.
Medical disclaimer:
This content is designed for postgraduate medical examination revision and does not constitute medical advice, diagnosis, or treatment guidance and must not be used as a substitute for professional clinical judgement, local guidelines, or specialist consultation. Clinical decisions should always be made in the context of individual patient circumstances and current national guidance.
