# Corrosive Poisoning > Corrosive poisoning in NEET-PG Medicine covering acid versus alkali injury, avoiding emesis and neutralisation, endoscopy timing, Zargar grading and strictures. - Canonical URL: https://prepelephant.com/topics/neet-pg/medicine/corrosive-poisoning - Exam / course: NEET-PG · Subject: Medicine - Publisher: PrepElephant (https://prepelephant.com) — Prepared and reviewed by the PrepElephant Academic Review Team - First published: 2026-10-14 - Last updated: 2026-10-14 - Reference basis: Reddy's Essentials of Forensic Medicine and Toxicology; Harrison's Principles of Internal Medicine - How to cite: "Corrosive Poisoning", PrepElephant, https://prepelephant.com/topics/neet-pg/medicine/corrosive-poisoning ## Direct answer Corrosive poisoning is tissue injury from strong acids or alkalis swallowed or applied to the body, and the agent type decides the injury pattern. Acids cause coagulative necrosis that often limits deeper penetration, while alkalis cause liquefactive necrosis that penetrates deeper and carries a worse prognosis. Management centres on dilution, avoiding emesis and neutralisation, and early endoscopy to grade injury and predict strictures. ## What you must remember - **Acids:** sulphuric, hydrochloric and nitric acids cause coagulative necrosis that forms a protective eschar, so deep penetration is less common than with alkalis. - **Alkalis:** caustic soda, potassium hydroxide and drain cleaners saponify fats and penetrate deeper, so oesophageal and gastric perforation are more likely. - **Contraindicated:** induced vomiting, activated charcoal and blind nasogastric tube passage, since each re-injures the mucosa or perforates the oesophagus. - **First aid:** small volumes of water or milk, given early if the patient is alert and not vomiting; neutralisation is avoided because the reaction releases heat. - **Endoscopy timing:** upper gastrointestinal endoscopy within about 24 hours of ingestion and not beyond 48 hours, once the patient is stable. - **Zargar grading:** grade 2b and grade 3 mucosal lesions are associated with stricture formation, which usually appears weeks later. - **Steroids:** routine corticosteroids and prophylactic antibiotics are not firmly established for preventing strictures, and the timing of steroids is debated. ## A graded pathway from ingestion to stricture prevention A patient who drank an unlabelled household liquid arrives drooling and in pain. The sequence below puts the airway first, then the agent, then timed endoscopy. 1. **Secure the airway:** look for stridor, hoarseness, drooling and oral burns, since laryngeal oedema can obstruct the airway within hours and may need early intubation. 2. **Identify the agent:** note the container, quantity, time of ingestion and whether the liquid is acidic or alkaline, because the agent type sets the injury pattern. 3. **Dilute, do not neutralise:** give small volumes of water or milk if the patient is alert and not vomiting, and avoid emesis, charcoal and blind tube passage. 4. **Watch for perforation:** shock, fever, chest or back pain and subcutaneous emphysema suggest perforation and need urgent surgical review. 5. **Scope within the window:** perform upper GI endoscopy at about 24 hours to grade mucosal injury; deep or circumferential lesions prompt feeding support and specialist review. 6. **Plan follow-up:** start oral feeding once swallowing is safe, and begin dilatation only if a stricture develops, usually after several weeks. ## Where the exam tries to catch you Most wrong answers treat a corrosive injury like a routine poisoning. - **Trap:** choosing gastric lavage or induced vomiting to clear the stomach — **Correct:** both are contraindicated, because the corrosive injures the already damaged oesophagus again on the way out or in. - **Trap:** neutralising the agent with vinegar or lemon juice — **Correct:** neutralisation releases heat and extends the burn, so only dilution is advised. - **Trap:** assuming alkali injury is milder because it hurts less — **Correct:** liquefactive necrosis penetrates deeper, so alkalis carry the worse prognosis. ## Frequently asked questions ### Which corrosive causes deeper injury, an acid or an alkali? An alkali usually causes deeper injury because it produces liquefactive necrosis, which dissolves tissue and allows penetration into deeper layers. Acids cause coagulative necrosis that forms a protective eschar and usually limits depth. Perforation is therefore a bigger concern after alkali ingestion. ### Why is gastric lavage avoided after a corrosive ingestion? Gastric lavage is avoided because a tube passed through an injured oesophagus can perforate it. Induced vomiting is also avoided, since the corrosive burns the mucosa again on the way up. Neither step removes the corrosive effectively, and both add injury. ### When should endoscopy be performed after corrosive poisoning? Upper gastrointestinal endoscopy is usually performed within about 24 hours of ingestion, once the patient is haemodynamically stable, and not beyond 48 hours. Early endoscopy grades mucosal injury and guides decisions about feeding, surgery and follow-up for strictures. ### Are corticosteroids routinely given to prevent oesophageal strictures after corrosive injury? Routine corticosteroids are not firmly established for preventing strictures after corrosive injury, and their role and timing remain debated. Some centres use them early in severe injury under specialist supervision. Antibiotics are reserved for documented infection or suspected perforation.