The main causes of nosebleeds are malnutrition, dry environment, allergy, nasal injury and so on. 1. Malnutrition: when the human body lacks certain vitamins, it will make frequent nosebleeds, such as atrophic rhinitis, etc., should eat more vegetables and fruits, and can eat less spicy food. 2. Dry environment: dry air is a major cause of nosebleeds, you can take: keep the nasal cavity moist, keep the environment moist, you can take the indoor use of humidifiers and other methods. 3. Allergy: when seasonal allergens increase, it can also cause nosebleeds, in normal times often open the window to change the air, as little as possible contact with allergens, if there are pets in the house, also need to be diligent in bathing, can reduce the occurrence of nosebleeds. 4. Nasal injury: when the nasal cavity is traumatized, such as cuts, nose picking injuries, can cause nosebleeds; usually should pay attention to nasal hygiene and develop good habits, try not to pick the nostrils, or poke the nostrils with foreign objects. When patients have nosebleeds, they should go to the hospital in time, and follow the doctor’s instructions to standardize the diagnosis and treatment after clarifying the cause of the disease, and do not delay the treatment.