Potassium Iodide (Potassium Iodide (KI))
Also sold as: SSKI (Saturated Solution of Potassium Iodide), Lugol's Solution (KI + Iodine), ThyroShield, Iosat, KI-65
Pregnancy
Cat N/A
Lactation
Caution
Schedule
OTC
Forms
Tablet 65mg (thyroid protection in radiation emergency) +3
Indications
- Radiation emergency: thyroid protection against radioactive iodine (I-131) exposure
- Preoperative preparation before thyroidectomy (Lugol's solution — reduces vascularity)
- Thyroid storm (Wolf-Chaikoff effect — inhibits thyroid hormone release)
- Chronic pulmonary disease (expectorant — SSKI, rarely used now)
- Cutaneous sporotrichosis (SSKI — antifungal)
- Iodine supplementation in severe deficiency
Adult Dosing
Radiation emergency (thyroid protection)
130mg (two 65mg tablets or one 130mg tablet) as single dose
Once per 24 hours; continue daily if ongoing radiation exposure
Must be given within 3–4 hours BEFORE (or within 3–4 hours AFTER) exposure to I-131 for maximum protective effect. Reduces I-131 thyroid uptake by ~100% if given prophylactically. For adults >40 years: benefit must outweigh risk of iodine-induced thyroid disease.
Preoperative thyroidectomy preparation (Lugol's solution)
3–5 drops (0.1–0.3 mL) of Lugol's solution TDS for 7–10 days before surgery
TDS, starting 10 days before planned thyroidectomy
Given AFTER achieving euthyroidism with antithyroid drugs. Reduces thyroid vascularity and intraoperative blood loss. Temporary effect — Wolff-Chaikoff escape occurs after ~14 days.
Thyroid storm (acute management)
SSKI 5 drops (250mg) orally every 6 hours, OR Lugol's 8–10 drops every 6 hours
Given at least 1 hour AFTER antithyroid drug (PTU or methimazole) to prevent iodine substrate from making new hormone
Critical sequencing: antithyroid drug FIRST, then iodide 1 hour later. Blocks hormone secretion via Wolff-Chaikoff effect.
Sporotrichosis (cutaneous)
SSKI 1 drop TDS initially, titrated to 40–50 drops TDS over 2–4 weeks
Increase dose weekly as tolerated for 4–12 weeks
Dilute in water/juice. Itraconazole preferred over SSKI for cutaneous sporotrichosis.
Pediatric Dosing
Neonates and infants are most vulnerable to radiation thyroid uptake and thyroid injury. In radiation emergency, treat all ages as benefit greatly outweighs iodine side effect risk in children.
Renal Dose Adjustment
| CrCl / eGFR | Dose Adjustment |
|---|---|
| Mild–moderate renal impairment | Use with caution — potassium accumulation risk (hyperkalemia). Monitor serum potassium. |
| Severe renal impairment / ESRD | Avoid or use with extreme caution — significant hyperkalemia risk. Consult specialist. |
Hepatic Adjustment
No specific dose adjustment required for hepatic impairment in acute use.
Pregnancy & Lactation
Pregnancy: Category N/A
Potassium iodide crosses the placenta. Prolonged use in pregnancy causes fetal goitre and hypothyroidism. For radiation emergency: acute single doses to protect fetal thyroid from radioactive iodine exposure are recommended — benefit outweighs risk in genuine radiation emergency. For preoperative/thyroid storm use: used short-term only under specialist supervision. Do NOT use for long-term thyroid suppression in pregnancy.
Lactation: Caution
Iodide concentrates in breast milk. Prolonged use may cause neonatal hypothyroidism or goitre. For radiation emergency, temporary cessation of breastfeeding or supplemental infant feeding recommended after maternal KI dose.
Top Drug Interactions
| Interacting Drug | Effect | Severity |
|---|---|---|
| ACE inhibitors (enalapril, lisinopril, ramipril) | Potassium iodide provides significant potassium load; additive hyperkalemia risk with potassium-sparing effects of ACE inhibitors. Monitor serum potassium. | Major |
| Potassium-sparing diuretics (spironolactone, amiloride, triamterene) | Additive hyperkalemia risk with KI potassium load; potentially life-threatening arrhythmia | Major |
| Antithyroid drugs (PTU, methimazole) | Sequential use in thyroid storm: antithyroid drug MUST be given first (1 hour before iodide). Given correctly, additive inhibition of thyroid hormone synthesis and release. If iodide given first, it provides substrate for new hormone synthesis — worsening outcome. | Moderate |
| Lithium carbonate | Additive antithyroid/hypothyroid effect; combined use may cause severe hypothyroidism and goitre | Moderate |
| Radioactive iodine (I-131) therapy | KI blocks thyroid uptake of I-131 — reduces efficacy of radioiodine therapy for Graves disease or thyroid cancer. Stop KI several days before scheduled radioiodine. | Major |
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Side Effects
Common
- Metallic or brassy taste in mouth
- Nausea and vomiting (especially with SSKI)
- Stomach upset
- Salivary gland swelling (iodism)
- Skin rash
- Acneiform eruption
- Runny nose and eye irritation (iodism)
Serious / Discontinue If
- Iodine-induced hyperthyroidism (Jod-Basedow phenomenon — particularly with pre-existing autonomous thyroid nodules)
- Iodine-induced hypothyroidism and goitre (with prolonged use)
- Hyperkalemia (especially in renal impairment)
- Hypersensitivity reactions (angioedema, anaphylaxis — rare)
- Thyroid adenoma exacerbation
Contraindications
- Known hypersensitivity to iodine or iodide
- Dermatitis herpetiformis (iodine worsens condition)
- Hypocomplementaemic vasculitis
- Long-term thyroid suppression (NOT appropriate — will cause Wolff-Chaikoff escape and rebound hyperthyroidism)
- Hyperkalemia or severe renal impairment (risk of dangerous potassium accumulation)
Available Indian Brands
| Brand | Manufacturer | Price (approx) |
|---|---|---|
| SSKI Solution | Glaxo Laboratories India | 100 mL ₹85 |
| Lugol's Solution | Himedia Laboratories | 100 mL ₹120 |
| KI Tablet 65mg | INTAS Pharmaceuticals | 10 tab ₹48 |
| ThyroShield KI 130mg | Fleming & Company | 14 tab ₹280 |
| Iosat 130mg | Anbex Inc (imported) | 14 tab ₹350 |
Monitoring Required
- Serum potassium (hyperkalemia risk, especially with renal impairment or potassium-sparing drugs)
- Thyroid function (TSH, free T4, free T3) — with prolonged use (>2 weeks)
- Signs of iodism (chronic iodide toxicity): metallic taste, hypersalivation, rhinitis, acne-like rash
- For radiation emergency use: thyroid ultrasound and TFT at 1–3 months post-exposure
- Blood pressure (fluid retention with prolonged use)
Patient Counseling Points
- For radiation emergency: take immediately as directed by public health authorities — take within 3–4 hours of exposure announcement.
- This medicine is NOT for long-term thyroid problems — it is for specific acute situations only.
- SSKI solution has an unpleasant metallic taste — dilute well in water, milk, or juice before taking.
- Lugol's solution for preoperative use: must only be taken after becoming euthyroid on antithyroid drugs — not a standalone treatment.
- Do not self-prescribe potassium iodide as a "radiation protection" supplement — only use in genuine emergencies as directed.
- Tell your doctor if you have kidney problems — potassium in this medicine can accumulate dangerously.
- If you have thyroid nodules, see your doctor before taking iodide — risk of triggering hyperthyroidism.
- Refrigerate SSKI solution after opening; check expiry dates on emergency tablets.
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Clinically reviewed by: Dr. Sanjay Kalra, DM (Endocrinology), Bharti Hospital Karnal
Last reviewed: 2026-03-20
References
- WHO Guidelines for Iodine Thyroid Blocking in a Nuclear or Radiological Emergency. 2017.
- FDA Guidance: Potassium Iodide as a Thyroid Blocking Agent in Radiation Emergencies. 2001.
- Indian Pharmacopoeia Commission. Potassium Iodide monograph. IP 2022.
- CIMS India Drug Database 2025 — Potassium Iodide
- Braverman LE, He X, Pino S et al. The effect of perchlorate, thiocyanate, and nitrate on thyroid function. J Clin Endocrinol Metab. 2005;90(2):700–706.