Each pills protection lasts up to 24 hours. Therefore a pack of IOSAT will last for 14 days of protection.
The US Nuclear Regulatory Commision (NRC) feels that Potassium Iodide is safe and effective. So much so that they stockpile KI to protect plant workers. Likewise FEMA the Federal Emergency Management Agency, stockpiles enough Potassium Iodide to care for people that cannot be evacuated during an emergency I.e. prisoners or government hospital patients.
The US is the only major nuclear power that does not stockpile for its citizens.
The FDA calls for the daily use of one IOSAT tablet (130mg of Potassium Iodide) for adults and children over 18 years old. Children ages 3 to 18 who weigh nless than 150lbs should take ½ tablet. Children ages one month to 3 years old should take ¼ tablet. Infants less than one month old need ¼ tablet. If necessary IOSAT can be dissolved in a liquid or in a soft food.