What if the pinching doesn't stop the bleeding no matter how long I do it?

First, make sure that you are putting firm pressure on both sides of your nostrils and that you hold your nose that way for at least 20 minutes without letting go. If this does not slow down the bleeding, then it is possible that the bleeding is coming from further back in the nose and pinching will not reach the vessel. Also, consider any medicine you have taken recently. For example, aspirin or other medicines that decrease your body's ability to form blood clots may also make bleeding last longer. Try using ice and medicated nasal sprays. These can help to shrink the blood vessels and slow the bleeding. See your doctor if heavy bleeding continues.