Potassium iodide (KI): FDA dosage by age

FDA dose table

Threshold Thyroid Radioactive Exposures and Recommended Doses of KI for Different Risk Groups (FDA FAQ, Q5). Officials decide whether your predicted exposure calls for KI; you do not measure it at home. [1][2]

Group	Predicted thyroid gland exposure (cGy)	KI dose (mg)	130 mg tablets	65 mg tablets	Oral solution, 65 mg/mL
Adults over 40 years	> 500	130	1	2	2 mL
Adults over 18 through 40 years	> 10	130	1	2	2 mL
Pregnant or lactating women	> 5	130	1	2	2 mL
Adolescents, 12 through 18 years*	> 5	65	½	1	1 mL
Children over 3 years through 12 years	> 5	65	½	1	1 mL
Children over 1 month through 3 years	> 5	32	Use KI oral solution**	½	0.5 mL
Infants birth through 1 month	> 5	16	Use KI oral solution**	Use KI oral solution**	0.25 mL

* FDA: “Adolescents approaching adult size (> 150 lbs or > 70 kg) should receive the full adult dose (130 mg).”

** FDA: “Potassium iodide oral solution is supplied in 1 oz (30 mL) bottles with a dropper marked for 1, 0.5, and 0.25 mL dosing. Each mL contains 65 mg potassium iodide.”

When to take it [1][3]

• Only when local public health or emergency officials, or a healthcare provider, tell you to. Not as a preventative.
• CDC: within 24 hours before or 4 hours after exposure to be most effective. FDA: works best within 3 to 4 hours of exposure.
• One dose protects for about 24 hours. Dose daily until the risk no longer exists, as officials direct.
• More is not better. A higher or more frequent dose does not add protection and can cause severe illness or death.
• Pregnant women and newborns: FDA does not recommend repeat dosing unless other protective measures are not available.

Who should not take KI [1]

• People with known iodine sensitivity, dermatitis herpetiformis, or hypocomplementemic vasculitis.
• People with nodular thyroid with heart disease.
• Use caution with multinodular goiter, Graves’ disease, or autoimmune thyroiditis.
• A seafood or shellfish allergy does not necessarily mean iodine allergy.
• Not sure? Ask your health care professional.

What KI does not do [1][3]

• It does not protect against other radioactive materials.
• It does not protect any part of the body except the thyroid.
• It is not a treatment and cannot reverse thyroid damage already done.
• It may not give 100% thyroid protection.
• Table salt, iodine foods, and iodine supplements are not substitutes. Use only FDA-approved KI.

Side effects [1]

• Possible: skin rash, swollen salivary glands, metallic taste, burning mouth or throat, sore teeth and gums, head cold symptoms, sometimes upset stomach and diarrhea.
• Allergic reaction signs: fever, joint pain, swelling of face, lips, tongue, throat, hands, or feet; trouble breathing, speaking, or swallowing; wheezing.
• Severe shortness of breath requires immediate medical attention.

This sheet repeats FDA and CDC guidance and is not medical advice. Ask your doctor or pharmacist about KI for your household.