Sayyiduna Salman (may Allah be pleased with him) narrated: Blood flowed from my nose, so I asked the Prophet (peace and blessings be upon him), and he (peace and blessings be upon him) said: "Perform a fresh ablution (wudu) for what has newly occurred."
Hadith Referenceالمعجم الكبير للطبراني / باب السين / 6074