Does Potassium Iodide Expire?

Short answer: KI tablets have labeled expiration dates, but the scientific evidence says they remain effective far beyond them. The NRC has publicly stated that potassium iodide tablets are "inherently stable" and "do not lose their effectiveness over time."

The FDA Shelf Life Extension Program (SLEP)

The U.S. government stockpiles enormous quantities of KI. Through the FDA's SLEP, government-held medications are tested years past their labeled expiration. SLEP testing has consistently shown that properly stored potassium iodide tablets maintain full potency well beyond their original dates.

Shelf Life by Product

• iOSAT 130mg: 10-year manufacturer guarantee
• ThyroSafe 65mg: 6-7 years (extensions possible)
• ThyroShield liquid: ~5 years (shorter due to liquid formulation)
• RadBlock: 12 years claimed

Degradation Indicators

Look for these signs that tablets may have degraded: yellowing or discoloration, moisture inside packaging, crumbling or powdering texture, very slow dissolution when placed in water. Even degraded tablets may still contain the active ingredient — crush and dissolve them rather than discarding.

Storage Best Practices

• Temperature: 59-86°F (15-30°C)
• Keep in original sealed packaging
• Away from light and moisture
• Ideal locations: bedroom closet, dedicated emergency shelf
• Avoid: bathroom (humidity), garage (temp extremes), vehicle long-term (heat)