Nosebleeds are usually extremely minor problems and are nothing to worry about. Children often experience nosebleeds, but most of the time, these nosebleeds are completely harmless. Frequent nosebleeds may be a sign of some underlying problem that you should attend to, but almost every child experiences a nosebleed once in a while without any serious cause or consequences.
A nosebleed is simply the bursting of a blood vessel in the nose; although this may sound serious, it is not. The nose is rich in blood vessels, and, particularly in children, these blood vessels are very delicate and susceptible to damage. Blowing the nose too hard, a slight blow to the nose, and several such minor actions could cause one of these blood vessels to burst, leading to a nosebleed. Since this is the first time your daughter has had a nosebleed and it lasted no longer than a minute, it was quite certainly something like this that caused it. The experience can be quite scary, but as long as she does not experience nosebleeds too often, there is no need to worry.
If your daughter ever has a nosebleed again, it is first of all important to reassure that there is nothing seriously wrong with her. Make her sit down, and then, with a handkerchief or a wad of cotton, pinch the lower part of her nose (not her nostrils) for 10 minutes, gently but firmly. Once the bleeding stops, make sure that your child does not rub or pick her nose, or exert herself for the next half hour.
answered by M W