The nasal passages can be blocked due to a swelling of the nasal membranes which is further caused by the swelling of the blood vessels. This expansion of the blood vessels can be caused by an attack of germs, an allergy to certain kinds of food items, pollen grains or even dust. Nasal congestion can on occasion become severe in young children and may even be fatal and requires immediate medical attention.
Since the most common cause is a flu accompanied by common cold and your daughter does not have one, you may want to check if she is allergic to any food product such as butter, cheese or ice cream. If she is, keep her away from the product and try steam inhalation twice a day. Since your daughter is only three, you may have to put her onto your lap and hold her while she inhales the steam. Burn a few cardamom seeds on hot coals and help your child breath in the smoke to clear the nasal passages. Pepper corns can similarly be burnt on fire and the fumes inhaled to provide relief from the congestion. You can prepare an inhaler at home and for this you will have to boil a glass of water and add half a teaspoon of salt to it. Pour into a sterilized bottle and while still warm use a dropper to pour two or three drops into each nostril while keeping the child’s head facing upwards. The solution will help liquefy the mucous and once it soaks the nostrils and throat, you may clean her nose up.
Make sure that her diet contains fresh fruits, vegetables, fish and whole grains. Tomato soup is an excellent remedy for this condition and you can make it at home by boiling three tomatoes in a cup of water. Grind some garlic into paste form and add to the water along with ground black pepper and a little salt to taste. Feed the soup to your child twice or thrice a day to clear out the phlegm and unblock the nasal passage. Give her warm baths and keep the body warm at all times. Hot tea or milk will help loosen the mucous and she can be given an extra pillow at night to be placed below the neck to relieve the congestion at night. In case these remedies do not work you may want to take her to your paediatrician for an opinion on her condition.