Potassium Iodide (KI)
Potassium iodide
Brand names:ThyroShield, iOSAT, ThyroSafe
A stable iodine compound used to saturate the thyroid gland and block uptake of radioactive iodine isotopes (primarily iodine-131) following nuclear reactor releases or radiological incidents. KI provides thyroid-specific protection only; it does not protect against other radioactive isotopes or external radiation exposure.
Pharmacology and Actions
Saturates thyroid iodine uptake mechanisms with stable (non-radioactive) iodine, preventing radioactive iodine isotopes from being concentrated in the thyroid gland. The thyroid uses iodine to produce thyroid hormones; in the presence of saturating stable iodine, the gland does not preferentially take up radioactive iodine that would otherwise concentrate and cause thyroid cancer. Most effective when administered before or within hours of radioactive iodine exposure. Provides no protection against external radiation or non-iodine radioactive isotopes (cesium-137, strontium-90, plutonium).
Indications
- Imminent or recent exposure to radioactive iodine from nuclear reactor incidents
- Nuclear weapons fallout exposure
- Radiological dispersal devices containing iodine isotopes
Absolute Contraindications
- Known iodine allergy
- Hypocomplementemic vasculitis
- Dermatitis herpetiformis
- Relative: history of Graves disease or autoimmune thyroid disease
Precautions and Side Effects
Gastrointestinal upset, metallic taste, salivary gland swelling, rash, iodism (chronic toxicity with prolonged use). Hypothyroidism with prolonged use (especially in pregnant women and neonates). Hyperthyroidism in patients with autonomous thyroid nodules. Most side effects are mild and self-limited with the short courses typical of nuclear incident response (1 to 14 days).
Adult Dosing
Pediatric Dosing
Children over 12 to 18 years (over 70 kg): 130 mg PO once daily. Children 3 to 12 years: 65 mg PO once daily. Children 1 month to 3 years: 32 mg PO once daily. Infants under 1 month: 16 mg PO once daily, single dose only without re-dosing unless reassessed by medical authority.
Pharmacokinetics
Peak Effect: 4 to 6 hours
Duration: 24 hours per dose
Storage and Handling
Room temperature 15 to 30 degrees C; protect from light and moisture. Tablets have shelf life typically 5 to 7 years. ThyroShield liquid formulation 1 to 2 years shelf life. Stockpile programs (SNS) maintain product through extended shelf life programs.
Reconstitution:
Tablets may be crushed and mixed with milk, juice, water, or formula for pediatric and infant dosing. Saturated solution of potassium iodide (SSKI) is an alternative formulation but not the standard incident-response product.
TCCC and TECC Role
Not a TCCC trauma medication. Standard component of CBRN response and nuclear incident public health preparedness. KI is included in Strategic National Stockpile (SNS) for population distribution and in nuclear power plant emergency planning zones (10-mile EPZ). FEMA and state-level distribution programs maintain KI for affected populations.
KI is the public health drug that gets searched massively during nuclear incident scares and is widely misunderstood. It is a thyroid-specific intervention and does nothing for other radioactive isotopes, external radiation, or radiation sickness. Stockpiling KI is appropriate for households in the 10-mile emergency planning zone around nuclear power plants; for the broader population, KI distribution would be coordinated through public health authorities in the event of a release. KI taken prophylactically without exposure is unnecessary and incurs side effect risk without benefit. Operationally, the timing window matters: KI is most effective given before or within 1 to 2 hours of radioactive iodine exposure; effectiveness drops sharply after 4 to 6 hours.
Treating KI as general radiation protection. It is not. KI protects only the thyroid gland and only against radioactive iodine isotopes. A casualty exposed to radiological materials that do not include iodine isotopes will not benefit from KI. The other common mistake is taking KI prophylactically without exposure risk, which incurs hypothyroidism risk without protective benefit. Public health authority guidance should drive KI administration timing and duration.
This drug profile is provided as educational reference material for trained medical providers. It is not medical advice, not a substitute for formal training, and not a substitute for current published guidelines or medical direction.
Drug administration is governed by your scope of practice, agency standing orders, medical director protocols, and applicable state and federal regulations. Controlled substances are subject to additional handling, accountability, and documentation requirements per DEA and state law. Always verify dosing, indications, contraindications, and route of administration against current published guidelines and your local protocols before administration.
If this content is being viewed during a medical emergency, call 911 immediately and follow the direction of your local emergency dispatch and medical control. Do not use this reference as a substitute for emergency medical services.
Drug information evolves. Last reviewed dates and source citations are provided for each entry. Confirm currency against the cited source before clinical use.
Penn Tactical Solutions publishes this reference for educational purposes. PTS does not provide medical direction and does not assume responsibility for clinical decisions made in the field. Clinical responsibility rests with the administering provider, their medical director, and their agency.
Educational reference for trained medical providers. Not medical advice. Not a substitute for formal training, current published guidelines, or medical direction. Drug administration is governed by your scope of practice, agency standing orders, medical director protocols, and applicable state and federal regulations. Controlled substances require additional storage, accountability, and documentation per DEA and state law.
In a medical emergency, call 911. This reference is not a substitute for emergency medical services.
Verify dosing, indications, and contraindications against current published guidelines and your local protocols before administration. Confirm content currency against the source citation. Penn Tactical Solutions does not provide medical direction. Clinical responsibility rests with the administering provider, their medical director, and their agency.
Potassium Iodide (KI)
| IV/IO | None (None) |
| IM | None (None) |
| IN | None (None) |
| PO | Adults over 18: 130 mg PO once daily for duration of exposure risk. Pregnant or breastfeeding women: same dose, limit to single dose unless reassessed by medical authority. Adults over 40: only with projected exposure greater than 500 cGy (very high threshold) due to lower thyroid cancer risk and higher hypothyroidism risk. (1 to 2 hours (thyroid saturation)) |