To many families, the holiday season is not complete without a decorated tree twinkling in the window. Each year, U.S. tree farmers sell an estimated 25 to 30 million pine and fir trees, according to the National Christmas Tree Association. For people with Christmas tree allergies, this abundance of pine and fir needles can make allergy symptoms difficult to control during holiday festivities.

Head lice are a common problem among school aged children, second only to the common cold, according to MayoClinic.com. If you notice signs of lice in your child's hair or on his scalp, don't panic. You can safely remove the lice and their eggs at home, without using an insecticidal shampoo. All you need is a comb with fine metal teeth to brush the lice and the eggs out of your child's hair.

Red, angry-looking, itchy rashes are a part of childhood. While most rashes are irritating and painful, they usually clear up without problems and are not a cause for concern. Topical irritation, allergies, fungi and viruses are all common causes of itchy rashes in children. You can help your child avoid itchy rashes by learning what triggers the rash and helping her avoid the irritant or allergen. If the rash is caused by a virus, vaccinating your child will help prevent it.

Nasal congestion often occurs due to colds or allergies. Stuffy noses often result from swollen nasal passage linings. A stuffy nose makes breathing difficult and causes discomfort for toddlers. The nasal congestion might get worse while your young child sleeps. Over-the-counter cold medications aren't recommended for toddlers and often aren't effective. Consider comfort measures at home to relieve your toddler's stuffy nose. While the cold won't go away faster, your toddler will likely feel better and breathe easier.

Bulimia nervosa is a type of eating disorder that causes teenagers and others suffering from it to consume excessive amounts of food in one sitting and then somehow purge the food from their bodies. Some bulimics remove the food by forcing themselves to vomit; others abuse laxatives or other medications. Teenage girls, particularly those in college, are more likely to suffer from bulimia than boys or younger teenagers.

All teenagers will act up or misbehave at some point or another. Rebellion and testing boundaries can be a normal part of maturing and reaching adulthood. In some cases though, rebellion and disruptive behavior can signal a problem that stretches beyond the usual teenage antics. Up to 16 percent of all teenagers have conduct disorder, a type of mental illness, according to WebMD. Teenagers with conduct disorder exhibit extremely aggressive behavior that puts themselves and others at risk.

The common cold is the only communicable health problem that beats out lice at the school age, according to MayoClinic.com. The small insects lay eggs, called nits, on the hair shaft to continue the population in the hair. The insects travel from one head to the next through direct contact with another person's hair or things that have touched the hair, such as brushes, scarves and hair clips. School prevention methods keep lice infestations to a minimum.

Candida albicans and other species of Candida yeast live on the skin and moist areas of the body, such as the mouth and genitals. Everyone, from babies to elderly adults, has yeast living on their bodies. Usually, the yeast doesn't cause harm. If the natural balance of microorganisms is disrupted, from illness, medications or changes in hormone levels, yeast can flourish, leading to an infection. Most yeast infections in children are treatable and will clear up quickly with medication.

An aching back causes discomfort and can interfere with daily activities, depending on the severity. While rare, children sometimes experience back pain just like adults do. The causes of the back pain vary and sometimes include serious medical conditions. Evaluating your child's back pain allows you to determine the need for medical interventions.

Toddler headaches range from mild to severe, with a variety of causes behind the pain. A young child can't always express the presence of a headache or the severity of the pain. Knowledge of toddler headache basics helps you decide how to treat your child's headache and whether or not medical intervention is necessary.