It is a condition most common in children and elderly people, that occurs at very low temperatures, generally during cold, dry winters.
Nosebleeds are caused either by fizical injuries, (nose trauma) but also by irritations, problems of the blood flow and blood pressure, coagulation problems, liver conditions, cancer (very rare).
The symptoms are very obvious, usually the blood comes only from one nostril, but depending on the blood flow, it can also reach the throat or stomach. If the person loses a lot of blood (which is quite rare for a nosebleed), a sensation of dizziness or fatigue can arise.
If blood also appears in urine or if a person bruises easily and the wounds heal slowly, it might indicate a blood coagulation problem and medical investigations are required.
Normally, medical assitance is not necessary in a nosebleed, but it is required if it happens very often, if the person has liver, kidney or heart disease or is undergoing treatment. If nosebleeds last for a long time (around 10 minutes), they occur often, or are accompanied by other symptoms, like fever or faint, it is necessary to go to a medical unit.
To prevent nosebleeds, first avoid irritating the nose and nostrils, by blowing the nose too hard, sneezing or smoking.
Humidity and temperature play an important role in this matter: keep a warm and moderately humit atmosphere during winter, to help keep the airways moist.
If a person is under a medical treatment, nosebleeds can be a side-effect; in this case, medical adivce is required.
How to react to a nosebleed
First, it is important to remain calm, to keep the blood pressure from rising and, consequently, lose even more blood. Sitting straight will prevent the blood from getting into the mouth and swallowing it (which may cause nausea or vomiting). Breathe through the mouth for about 10 minutes, holding the nostrils together at the same time, to give the blood in the area a chance to clot.
Do not apply ice on the area of the nose. Add moisture in the air with a humidifier or by placing a recipient filled with water near the heating source of your room or house.