Lugol iodine 💊
Related Subjects:
|Thyrotoxicosis and Hyperthyroidism
|Carbimazole
⚠️ Thyroid storm: start iodine at least 1 hour after the first dose of carbimazole or propylthiouracil. Iodine given first provides substrate for new hormone synthesis and can worsen thyrotoxicosis.
📖 About
- Lugol's iodine (aqueous iodine oral solution) contains iodine 5% and potassium iodide 10% - about 130 mg total iodine per mL (roughly 6–8 mg per drop).
- Used short term only - the gland "escapes" the effect after about 10–14 days.
- Always check the BNF for the latest guidance.
⚙️ Mode of Action
- High-dose iodide inhibits release of stored T4/T3 (the fastest anti-thyroid effect).
- Wolff–Chaikoff effect: transient inhibition of iodine organification → ↓ hormone synthesis.
- Reduces thyroid vascularity and size → helpful before thyroidectomy.
🎯 Indications
- Thyroid storm - adjunct to a thionamide, beta-blocker, corticosteroid and supportive care.
- Pre-operative preparation for thyroidectomy in Graves' disease (usually 10 days before surgery).
- (Potassium iodate tablets are a separate product used for radiation emergencies.)
💊 Dose (adult, by mouth, well diluted in milk or water)
| Indication | Dose |
|---|
| Pre-operative thyrotoxicosis (BNF) | 0.1–0.3 mL three times daily for 10–14 days before surgery |
| Thyroid storm | Per endocrinology/local protocol - commonly 0.25–0.5 mL (about 5–10 drops) every 6–8 hours, starting ≥1 hour after the thionamide |
🔄 Interactions
- Lithium: additive hypothyroid effect.
- Amiodarone and iodinated contrast: additional iodine load.
- Potassium-sparing diuretics, ACE inhibitors: potassium iodide adds potassium (hyperkalaemia risk).
- Interferes with radioiodine uptake scans and treatment for weeks.
⚠️ Cautions
- Not for long-term treatment of thyrotoxicosis.
- Pregnancy: crosses the placenta → neonatal goitre and hypothyroidism - use only short term if essential.
- Breastfeeding: concentrated in milk - avoid.
- Children.
🚫 Contraindications
- Iodine hypersensitivity.
- Avoid in hypocomplementaemic vasculitis, dermatitis herpetiformis and pulmonary tuberculosis.
💥 Side Effects
- Iodism: metallic taste, burning mouth and throat, sore teeth and gums, ↑ salivation, coryza, conjunctivitis, headache, parotid swelling.
- Rash (acneiform), GI upset.
- Hypersensitivity: angio-oedema, fever, arthralgia, eosinophilia.
- Paradoxical iodine-induced hyperthyroidism (Jod-Basedow) or hypothyroidism.
📚 References
