The reasoning: types of adverse event
| Type | Mechanism | Examples |
|---|---|---|
| Physiological (dose/osmolality related) | osmotic, vasovagal, chemotoxic | warmth, metallic taste, nausea, vasovagal hypotension with bradycardia, arrhythmia |
| Allergic‑like (hypersensitivity) | mostly non‑IgE direct mast cell activation (anaphylactoid); some IgE | urticaria, angioedema, bronchospasm, laryngeal oedema, anaphylactic shock |
| Delayed | T‑cell mediated | rash 1 hour to 1 week later |
| Renal | haemodynamic + tubular toxicity | contrast‑associated / contrast‑induced AKI |
| Thyroid | iodine load | thyrotoxicosis in Graves' or multinodular goitre; caution before planned radioiodine |
| Local | extravasation | swelling, rarely compartment syndrome |