In short, NO, dry chemical extinguisher powder is considered non-toxic. However, precautions should be taken when dealing with all types of dry chemical. It is best to wear gloves and a dust mask to prevent irritation from skin contact or inhalation. When inhaled In larger quantities, dry chemical can severely irritate mucous membranes and cause breathing complications. It is highly unlikely that enough powder would be inhaled when using a fire extinguisher to have any adverse reactions. If you are faced with a situation where you have inhaled a large amount of dry chemical, or have been sprayed directly in the eyes, you should seek medical attention immediately. Overall, fire extinguisher powder is very safe when used properly. If you have used a fire extinguisher it is imperative you either get it re-charged by a professional, or replace the unit with a new one.
This information only applies to dry chemical extinguishers. Other extinguisher types have different precautions regarding toxicity. We hope this information has been valuable and you never find yourself in a situation in which an extinguisher is necessary.