Despite some bright spots, national statistics on illicit drug use are alarming.

More than a third of US high school students have tried an inhalant or illicit drug by the time they are in eighth grade. More than half use an illegal drug by the time they finish high school. Eighty percent of today's high school students have used alcohol.

So if your teen suddenly becomes moody, is spending time with a different group of friends, or starts failing in school, you may wonder if drugs are to blame.

Medically testing your teen for drug use may seem like a straightforward way to get an answer. But it probably is not the best way.

Drug tests are not always reliable, and your teen may resent being tested. Other methods may be better. Through confidential interviews and questionnaires, your pediatrician can help assess whether your teen has a drug problem without resorting to lab tests.

If your teen does undergo a drug test, it should be voluntary. The American Academy of Pediatrics (AAP) opposes involuntary drug tests. Consult your pediatrician if you believe your teen should be tested for drug use.

Types of drug testing

Drug tests most commonly analyze urine. However, many body tissues and fluids can be tested for drug use. Hair, saliva, nails, and sweat are among them. Some of these alternatives show promise. For example, hair tests are difficult to fool and may reveal drug use months after it occurs.

But hair tests are fairly new and do not detect recent drug use. Hair color and type or secondhand marijuana smoke also may skew hair test results. Saliva, nail, and sweat testing need to be refined as well.

Limits of urine drug testing

A chemical analysis of urine—or urinalysis—is the most common drug test. But the test has limits and parents should consider the following pitfalls:

• Test may not detect all illicit drugs. Most routine urine tests do not catch LSD, ketamine, Ecstasy, inhalant, or anabolic steroid use. They also may not detect alcohol, the substance that teens are most likely to use.

• Test results may be false negatives. Other drugs are detectable for only a short time after they are used. Most drugs—other than marijuana—can be flushed from the user's system in as few as 12 hours. Within 2 or 3 days, these drugs are almost always undetectable.

  Teens also may try to "cheat" on a urine test. They might dilute their urine samples with tap or toilet water, or drink a lot of water before the test to flush drugs from their systems. Some users buy products designed to beat the test at nutritional supplement stores or through the Internet.

• Test results may be false positives. Urine tests that do detect drug use may be misleading and should be confirmed by more specific tests.

  For instance, routine urine test results may show marijuana use days—or even weeks—after your teen has quit using the drug. Some drug tests may mistake traces of legal painkillers containing ibuprofen or naproxen for signs of marijuana use.

  Sinus or allergy medicines may show up as amphetamines in drug tests. Other common medicines can test as tranquilizers.

  The poppy seeds baked into many foods can cause false positives for opiate use. Some antibiotics also may show up as opiates in tests.

  Keep these possibilities in mind if your teen does take a drug test. Consider the test a preliminary screen. Most importantly, seek additional lab tests to confirm any positive results.

  While further analysis can almost always pinpoint the cause of a positive drug test, it may take days or weeks to complete. Meanwhile, remember that your teen may be bearing the brunt of false suspicion—so try to avoid jumping to conclusions until all the results are in.

• Testing may damage the pediatrician-patient relationship. Involuntary drug testing may undermine your teen's trust in your pediatrician. Even results showing no drug use can be harmful if your teen feels coerced into the test. If your teen does use drugs, trust in your pediatrician is vital to successful substance abuse treatment.

When drug testing may be helpful

The court system or your teen's school may require a drug test. While still a controversial policy, many schools screen young athletes for drug use. Some private schools test all their students.

Urine tests also may help teens who are receiving drug treatment stay away from drugs.

If drug testing is called for, you and your pediatrician should work together to ensure you get reliable lab results. Make sure your teen's sample is carefully collected and handled by an experienced, certified laboratory. Guard against human error or false positives. Be certain the results are properly recorded and kept confidential.

Finally, remember that a lab test is just one measure of drug use. Your pediatrician also will take into account your teen's behavior as a whole.

Is home drug testing advisable?

You can buy home drug testing kits at pharmacies or through the Internet. But home test kits also may give false or deceptive results.

Accurate or not, the test can create hard feelings. Your teen may resent what seems to be a clear sign of distrust and become less open with you. Or anger could turn to rebellion. At the least, a resentful teen is less likely to turn to you for the emotional support that helps deter drug use.

Without a drug test, how can I tell if my teen is using drugs?

Certain symptoms and behaviors are red flags for drug use. But keep in mind they may also indicate other problems, such as depression.

Look for

• Alcohol, smoke, or other chemical odors on your teen's breath or clothing

• Obvious intoxication, dizziness, or bizarre behavior

• Changes in dress and grooming

• Changes in choice of friends

• Frequent arguments, sudden mood changes, and unexplained violent actions

• Changes in eating and sleeping patterns

• Loss of interest in activities

• Truancy

• Failing grades

• Runaway and delinquent behavior

• Suicide attempts

How your pediatrician can help

Your pediatrician may be able to identify drug use by interviewing your teen. Though you may want to participate, let the doctor talk to your teen alone and in strict confidence.

Privacy is crucial. One-on-one talks are most likely to produce the honest answers from your teen that you need.

Teens also want to know their answers to drug use questions will remain confidential. Your pediatrician will respect your child's privacy, but will tell both of you up front that a breach of confidentiality could occur if

• Your teen requires parental assistance.

• Your teen agrees to your request for information.

• Your teen lies to your pediatrician.

• Your pediatrician believes your teen may come to harm or harm someone else.

Do not worry that you will be kept in the dark about a serious problem. Your pediatrician will tell you if your teen is at immediate risk.

Resources

Below is a list of Internet sites that focus on substance abuse. This list is not comprehensive, but includes sites with links to other resources.

• National Institute on Drug Abuse, a division of the National Institutes of Health

  http://www.nida.nih.gov

• For Real, sponsored by the Center for Substance Abuse Prevention

  http://www.forreal.org/

• Parenting is Prevention, sponsored by the Center for Substance Abuse Prevention

  http://parentingisprevention.org/

• American Council for Drug Education

  http://www.acde.org/

• National Clearinghouse for Alcohol and Drug Information, sponsored by the Center for Substance Abuse Prevention

  http://www.health.org/

• Medem, founded by the American Academy of Pediatrics and other national medical societies

  http://www.medem.com/MedLB/articleslb.cfm?sub_cat=23

Remember

Some teens can stop using drugs based on a strong personal desire to change their lives, and little else. Others stop using drugs when they learn about the risks and potential costs of substance abuse. Many youths stop using alcohol or drugs as they reach late adolescence.

But sometimes teens need outside help to quit. Your pediatrician can help you find the right counseling and treatment. That may mean psychiatric treatment. Or it may mean a referral to a detoxification program.

Teen drug use is a serious problem. You do not have to handle it alone. Do not be afraid to seek professional help from your pediatrician, a counselor, support group, or treatment program. They can help you provide the support that is so crucial to the success of any treatment program.