Mylar balloons are sensitive to temperature changes: at low temperatures they may appear deflated, while warm air causes them to expand again. Excessive heat can cause the helium to expand and may lead to the balloon bursting.

As they are conductive, they must not be released outdoors if filled with helium and should not be used near overhead power lines. It is recommended to use non-metallic ribbons and always secure the balloon to a weight to prevent it from flying away.

When filled with helium, these balloons float for approximately 3–5 days and can be re-inflated. They can also be inflated with air for fixed decorations.