Updated December 30, 2014.

Written or reviewed by a board-certified physician. See About.com's Medical Review Board.

Being a teenager has never been easy, but except for acne, teens have usually outgrown many of the health problems that younger kids have, like frequent ear infections and sinus infections. Many kids have even outgrown their asthma and eczema problems, or at least gotten better by the time they are teenagers.

Unfortunately, teens are at risk for other health hazards, which can be even more of a problem because they can be more hidden from these kids, their parents, and even their doctors.

While child obesity would be considered an obvious health hazard to most people, other hidden health hazards can include the risk of permanent hearing loss from listening to loud music on an iPod, developing type 2 diabetes or high cholesterol from being overweight, or abusing a parent's prescription pain medication.

Becoming more aware of these hidden health hazards can help to make sure that your child is not at risk and get him help if he is.

Hearing Loss

Many teens play music on their iPod or other MP3 player at full volume with earbuds or headphones, which can put them at risk for permanent hearing loss.

Even temporary hearing problems these kids may have, such as ringing in their ears (tinnitus), having ears that feel stopped up, or noticing that voices and other sounds become muffled by the end of the day, are likely caused by their listening to loud music and not to an ear infection, allergies or ear wax.

To help avoid hearing loss from your teen's iPod or other MP3 player, you should:

• warn your kids that they should listen to music at a volume so that they can still hear things around them, even with their earbuds or headphones in place
  
  
• teach your kids warning signs that they are listening to music too loud, such as ringing in their ears and temporary hearing loss
  
  
• set the maximum volume limit on your child's MP3 player. On an iPod or iPhone, go to Settings - iPod - Volume Limit, and at most, lock the maximum volume limit at 50 to 60 percent (70 to 80 decibels) of the total volume
  
  

Most importantly, make sure your kids understand that at full volume (100 to 110 decibels), it only takes about five minutes to cause some hearing loss. While sounds that are equal to 70 to 80 decibels are about the same as the noises on a busy street, anything over 80 decibels can be harmful, especially if you are exposed to them for long periods of time. A jet plane taking off, for example, is equal to about 120 decibels.

In addition to an iPod or other MP3 player, loud toys are another source of hidden noise that can damage your child's hearing, especially since many young children like to hold toys up to their ears.

Type 2 Diabetes

Although once thought of as adult-onset diabetes mellitus, type 2 diabetes is now becoming more common among teens, especially overweight teens.

Type 2 diabetes is especially common in preteens and teens who:

• have a strong family history for type 2 diabetes
  
  
• are obese, with a body mass index (BMI) that is above the 95th percentile for their age
  
  
• have signs of insulin resistance, such as acanthosis nigricans, because their body doesn't use insulin properly anymore and requires higher levels of insulin to try and regulate blood sugar, until they eventually start to make less insulin may develop classic symptoms of diabetes
  
  

The risk factors for type 2 diabetes, such as childhood obesity, are usually very well known to parents and children. So why is type 2 diabetes still a hidden health hazard? Mostly because most teens with type 2 diabetes don't have any symptoms of diabetes or they have very mild symptoms.

If your child has signs or symptoms of type 2 diabetes, or is overweight and is at risk for developing type 2 diabetes, learning to eat healthier, losing weight, and daily physical activity can be helpful.

High Cholesterol

With the rise in childhood obesity has come another more hidden health hazard, an increased number of kids with high cholesterol.

Although genetics plays an important role in whether or not someone will have high cholesterol, many experts think that a poor diet and lack of physical activity are just as important.

To help prevent and control high cholesterol, it can help to:

• encourage kids who are at least two years old to drink low-fat dairy products, although you may introduce low-fat dairy products as early as 12 months of age if a child is already overweight or has a family history of obesity, high cholesterol, or cardiovascular disease
  
  
• encourage kids, especially those at high risk for cardiovascular disease, to eat healthy and exercise for at least one hour each day
  
  
• screen children for high cholesterol with a fasting lipid profile (total cholesterol, HDL, LDL) between age two and ten years if other family members have high cholesterol, premature cardiovascular disease (heart attacks and stroke, etc.), or dyslipidemia (abnormal lipid levels).
  
  
• also screen children if they are overweight, have high blood pressure, smoke cigarettes, or have diabetes
  
  
• help kids lose weight if they have high cholesterol and are overweight
  
  
• consider medications to control high cholesterol for those kids who continue to have high cholesterol despite diet therapy, especially if they have other risk factors, such as diabetes, high blood pressure, or a family history of premature cardiovascular disease (see a lipid expert)
  
  

STDs

Most parents don't think their teens are sexually active.

Unfortunately, almost half of high school students are, and many don't use a condom that could protect them from many sexually transmitted diseases (STDs).

Keeping in mind that about 60 percent of 12th graders and 30 percent of 9th graders report that they have had sex, it is important to:

• talk to your kids about sex, including the benefits of waiting to have sex until they are older
  
  
• discuss the risks of unprotected sex, including pregnancy and STDs, like Chlamydia, genital herpes, gonorrhea, genital warts (HPV), syphilis, and HIV
  
  
• teach your kids the symptoms of STDs, which, depending on the STD, can include abnormal discharge from the penis or vagina, burning with urination, or red bumps, blisters, or open sores on the penis, vagina, or areas close by
  
  
• remind your sexually active kids that STDs can sometimes have no symptoms at all
  
  
• ask your pediatrician to talk to your teen about their sexuality, including stages of puberty, sex education, and other things your teen might have questions about
  
  
• get your teen vaccinated with the HPV vaccine (Gardasil or Cervarix), which is routinely given to girls when they are 11 or 12 years old
  
  
• follow the CDC guidelines which encourages routine HIV testing beginning when kids are 13 years old, because routine screening will help to diagnose those teens who do not admit to being sexually active