Potassium iodide is used to thin mucus and loosen congestion in the chest and throat. Potassium iodide is used in people with breathing problems that can be complicated by thick mucus, such as asthma, chronic bronchitis, or emphysema.

Potassium iodide is used during a nuclear radiation emergency to block radioactive iodine from entering your thyroid gland. For this purpose, the medicine is usually taken only once or twice.

Potassium iodide may also be used for purposes not listed in this medication guide.

You should not use potassium iodide if you ar allergic to iodide or iodine.

You may not be able to use potassium iodide for exposure to nuclear radiation if you have:

• thyroid nodules and heart problems;
• dermatitis herpetiformis (Duhring disease, itchy skin rash common with celiac disease); or
• inflammation of the small blood vessels (hypocomplementemic urticarial vasculitis, or HUV) that causes episodes of hives, itching, burning, and painful skin sores.

Tell your doctor if you have ever had:

• a thyroid disorder;
• Addison's disease (an adrenal gland disorder);
• heart disease;
• tuberculosis;
• bronchitis;
• kidney disease; or
• myotonia congenita (a genetic muscle disorder).

Potassium iodide is used in children only during a nuclear radiation emergency. Do not give this medicine to a child without medical advice.

Potassium iodide can cause thyroid problems in both mother and baby when used during pregnancy. However, the benefit of taking this medicine to protect your thyroid from nuclear radiation exposure far outweighs any risks of thyroid harm.

Any pregnant or breastfeeding woman or infant who takes potassium iodide should have their thyroid function checked after using this medicine. Seek medical care as soon as possible.

If you are breastfeeding, tell your doctor if you notice a skin rash, muscle weakness, yellowed skin, breathing problems, feeding problems, or unusual crying in the nursing baby.

Use Potassium Iodide (Pima) exactly as directed on the label, or as prescribed by your doctor. Do not use in larger or smaller amounts or for longer than recommended.

Get emergency medical help if you have signs of an allergic reaction: hives, rash; fever, swollen glands, joint pain; wheezing, difficult breathing, trouble swallowing; swelling of your face, lips, tongue, or throat.

Stop using potassium iodide and call your doctor at once if you have:

• fever, tiredness;
• swelling in your neck or throat (enlarged thyroid, or goiter);
• chest pain, irregular heartbeats;
• numbness, tingling, pain, weakness, or swelling in your hands or feet;
• a weak or heavy feeling in your legs; or
• bloody or tarry stools, coughing up blood or vomit that looks like coffee grounds.

High doses or long-term use of potassium iodide may cause iodine poisoning. Tell your doctor if you have symptoms such as burning in your mouth or throat, a metallic taste, tooth or gum pain, drooling, severe headache, cold symptoms (stuffy nose, sneezing) eye irritation, or severe skin rash.

Common side effects may include:

• swelling or tenderness in your lower jaw;
• rash; or
• nausea, vomiting, diarrhea, upset stomach, or stomach pain.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Follow your doctor's instructions about any restrictions on food, beverages, or activity.