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potassium iodide

S01XA04

Forms & Strengths

Oral tablets 65 mg potassium iodide
Oral solution 2 % (w/v)
Ophthalmic solution 5 % (w/v)
Topical ointment 1 %

Adult Dosing

Radiation thyroid blockade: 130 mg PO loading dose, then 65 mg PO daily
Hypothyroidism/iodine deficiency: 50–100 mg PO daily
Expectorant for cough: 30–90 mg PO q6h
Ophthalmic antiseptic: 1–2 drops instilled QID

Pediatric Dosing

Radiation blockade: 130 mg/m² PO loading, then 65 mg/m² daily (max 130 mg)
Iodine deficiency: 25–50 mg PO daily (age‑adjusted)
Cough expectorant: 10–30 mg PO q6h (max 90 mg/day)
Ophthalmic: 1 drop per eye QID

Indications

Thyroid blocking prior to radioactive iodine exposure
Iodine supplementation in hypothyroidism or dietary deficiency
Expectorant for productive cough
Pre‑operative thyroid suppression
Topical ophthalmic antiseptic

Mechanism of Action

Provides inorganic iodide substrate, saturating the Na⁺/I⁻ symporter (Wolff‑Chaikoff effect) to block thyroid uptake
Iodide facilitates formation of hypoiodous acid, exerting antimicrobial activity in ophthalmic preparations
Increases airway secretions and reduces viscosity, aiding mucociliary clearance

Contraindications

Known allergy to iodine or potassium iodide
Uncontrolled hyperthyroidism (risk of iodine‑induced thyrotoxicosis)
Dermatitis herpetiformis or other iodine‑sensitive skin disorders

Adverse Reactions

Skin rash, pruritus, urticaria (iodine allergy)
Iodism: metallic taste, salivation, fever, GI upset
Transient hypo‑ or hyperthyroidism
Ophthalmic irritation: burning, redness

Drug Interactions

Lithium – increased risk of lithium toxicity due to thyroid effects
Antithyroid drugs (e.g., propylthiouracil, methimazole) – reduced efficacy of potassium iodide blockade
Amiodarone – additive iodine load, potential thyroid dysfunction
Radioactive iodine therapy – competition for thyroid uptake

Curated Content: Needs Vetting Before Put to Clinical Use