Indications
Potassium iodide is a source of iodine. It is used in supplements to prevent iodine deficiency and goitre (an enlarged thyroid gland), especially during pregnancy and breastfeeding. Only on official instruction, it is also used to protect the thyroid after a nuclear or radiation emergency. Doctors may use it before some thyroid operations and for certain fungal skin infections; these uses are as prescribed.
How It Works
The thyroid gland uses iodine to make thyroid hormones, which control the body’s energy use and are essential for a baby’s brain development. In large doses, potassium iodide fills the thyroid with ordinary iodine so that radioactive iodine is not taken up, and it briefly reduces thyroid hormone release.
Dosage and Administration
- Supplements: usually provide about 150 mcg of iodine a day for adults and about 250 mcg a day in pregnancy and breastfeeding. Follow the pack or your doctor.
- Radiation emergency: take only when public health authorities say so, at the dose they give.
- Other uses: as prescribed.
Take with or after food, with a full glass of water or milk.
Interactions
Taking it with Lithium or antithyroid medicines (such as Carbimazole and Methimazole) can cause an underactive thyroid. Amiodarone also contains a lot of iodine. At high doses, using it with medicines that raise potassium (such as Spironolactone, Amiloride, Enalapril or Losartan) can make blood potassium too high.
Contraindications
- Allergy to iodine, iodide or any ingredient of the product.
- Dermatitis herpetiformis (an itchy, blistering skin condition) or hypocomplementaemic vasculitis (a rare inflammation of blood vessels).
- Overactive thyroid or thyroid nodules, unless a doctor advises it.
Side Effects
At supplement doses side effects are uncommon. Higher doses can cause stomach upset, a metallic taste, more saliva and an acne-like rash.
Get urgent medical help if you have: swelling of the face, lips or throat or difficulty breathing; fever with joint pain or rash; a fast heartbeat, shaking, sweating and weight loss (overactive thyroid); marked tiredness, feeling cold or neck swelling (underactive thyroid); or painful swelling of the glands under the jaw.
Pregnancy and Lactation
Iodine is essential in pregnancy and breastfeeding, and normal supplement doses are recommended. High doses taken for a long time can cause goitre or an underactive thyroid in the baby, so take higher doses only on medical advice. In a radiation emergency, follow official advice, as protection is especially important for pregnant and breastfeeding women.
Precautions and Warnings
Tell the doctor if you have thyroid disease, kidney disease or high blood potassium. Do not take high doses for a long time without medical supervision. Remember that iodised salt and other supplements also contain iodine.
Overdose
Overdose can cause burning in the mouth and throat, a metallic taste, sore teeth and gums, stomach pain, vomiting and diarrhoea. Seek medical help. Long-term excess can upset thyroid function.
Therapeutic Class
Iodine supplement; thyroid blocking agent.
Storage
Store below 30°C in a dry place, away from light and out of the reach of children.
Prepared by the Oshud Alo team from standard drug references. For information only; always follow your doctor's advice.