Over-tightening your headgear can lead to mask leaks. Tightening the top straps too much can cause leaks at the mouth while tightening the bottom straps too much can cause blowing at the eyes. Clients are to loosen off their headgear and slowly re-tighten the straps just until the leak stops. Another cause of leaks is a worn-out mask or mask part that may need to be replaced.