Why toddlers get them

The lining inside the nose is thin, sits over a dense mesh of small blood vessels, and is within easy reach of a small finger. The NHS puts the everyday causes simply: picking the nose, blowing it too hard, and "the inside of your nose being too dry (maybe because of a change in air temperature)." It also lists children first among the groups more likely to get nosebleeds.

The American Academy of Pediatrics adds the ones that matter most in the toddler years. Colds and allergies cause swelling and irritation inside the nose and can lead to spontaneous bleeding. Trauma covers picking, pushing something into a nostril, blowing too hard, or a knock from a ball or a fall. Low humidity dries the lining out, which is why nosebleeds cluster in winter when the heating is on. The AAP is reassuring about frequency: some preschoolers have several a week, and this "is neither abnormal nor dangerous, but it can be very frightening."

How to stop one

The NHS, HSE and AAP describe the same method, and the timings are the part people get wrong.

Sit them up and lean them forward. The NHS says to sit down and lean forward with the head tilted forward and the mouth open. The AAP is explicit about why: do not let a child lie down or lean back, because that lets blood run down the throat and may make them vomit.
Pinch the soft part, not the bridge. The NHS says to pinch just above the nostrils for 10 to 15 minutes. The AAP describes it as the soft lower half of the nose, held firmly.
Do not keep checking. The AAP's instruction is the most useful one on the page: "don't look to see if your child's nose is bleeding during this time; you may start the flow again." Releasing the pressure interrupts the clot that is forming.
Breathe through the mouth. Both services say the same. A toddler will manage this better sitting on a lap facing outwards, watching something.
Do not pack the nose. The AAP says do not stuff tissues, gauze or any other material into the nose to stop the bleeding.
Ice is optional. The NHS says holding an ice pack or bag of frozen peas wrapped in a tea towel on the top of the nose may help reduce blood flow, but adds honestly that "the evidence to show it works is not very strong." The HSE mentions the neck or nose, or chewing ice.

If bleeding has not stopped after the first 10 minutes, the AAP says to repeat the pressure for another 10. If it persists after that second attempt, call a doctor or go to the nearest emergency department while continuing to hold pressure.

Afterwards

The NHS advises avoiding a short list of things for 24 hours to reduce the chance of another bleed: blowing the nose, picking it, hot drinks, heavy lifting or strenuous exercise, picking scabs, and lying down flat. For a toddler that mostly means a quiet afternoon and keeping fingers busy. The HSE adds a reassuring detail: a blood clot may come out of the nose afterwards, and that is normal.

When to go to A&E

The NHS lists these as immediate-action reasons to go to A&E with a nosebleed:

the nosebleed lasts longer than 10 to 15 minutes;
the bleeding seems excessive;
the child is swallowing a large amount of blood and it is making them vomit;
the bleeding started after a blow to the head;
they feel weak or dizzy;
they are having difficulty breathing.

The NHS adds that you should not drive yourself to A&E, and should ask someone else to drive or call 999. The HSE gives an almost identical list for Ireland.

The AAP's parallel list for calling a doctor straight away is worth knowing because it is symptom-led rather than clock-led: if a child is pale, sweaty or not responding to you; if you believe they have lost a lot of blood; if they are bleeding from the mouth or vomiting blood or brown material that looks like coffee grounds; or if the nose is bleeding after a blow or injury to any part of the head. It also says to call the emergency number any time a child is unresponsive.

The under-2 rule

This is the piece most parents have never heard. Both the NHS and the HSE say to see a GP if a child under 2 years old has had a nosebleed. Spontaneous nosebleeds are genuinely unusual at that age, so the advice is to have it looked at rather than to treat it as one of those things.

When to see a GP about repeated nosebleeds

The NHS says to see a GP if you or your child have regular nosebleeds, if there are symptoms of anaemia such as a faster heartbeat, breathlessness or skin paler than normal for them, or if there is a known clotting problem or blood-thinning medicine involved. The GP may test for anaemia or a clotting condition.

The AAP sets a specific trigger for investigation: if a child's nosebleeds routinely last longer than 8 to 10 minutes, a doctor may want to test for a blood clotting disorder. It also says a child with severe or recurrent bleeding, or bleeding from both nostrils, should be assessed, and may be referred to an ear, nose and throat specialist. Another prompt it gives is a lot of nosebleeds together with a chronically stuffy nose that never seems to clear, which can point to a fragile vessel or a growth in the nasal passage.

Where a single fragile vessel is the cause, the fix is usually straightforward. The NHS describes cautery, in which a doctor seals the bleeding point with a chemical-tipped stick, and packing with ribbon gauze or sponge if cautery is not possible. Neither is something to be alarmed by.

Reducing how often they happen

Most prevention is about the lining of the nose, not the child's behaviour. Keeping bedrooms from getting too hot and dry over winter helps, as does treating a cold or hay fever that has the child rubbing and blowing constantly. Short fingernails reduce the damage done by picking, and a distraction — something to hold in the car, at story time, in front of the television — works better than telling a toddler to stop. If your child has frequent nosebleeds, the AAP suggests asking a doctor about what else can be done rather than cycling through home remedies.

Toddler Nosebleeds: How to Stop One, When to Worry