The belief that a child is using drugs leads to a host of emotions for a parent -- anger, guilt and a sense of failure among them. Most experts agree that parents shouldn't blame themselves. Drug use cuts across all economic, social and educational backgrounds. It occurs in "happy" and "unhappy" homes. Instead of focusing on "what might have been," parents need to take action to help their children.

The National Institute on Drug Abuse conducts yearly surveys about drug use among students in eighth grade, 10th grade and 12th grade. Here are some recent findings:

• 54.3 percent of students in the graduating class of 1997 reported using illicit drugs by the time they reached 12th grade.
• Alcohol remains the top substance used: 54 percent of eighth-graders, 72 percent of 10th-graders and 82 percent of 12th-graders reported having consumed alcohol.
• In 1997, nearly 50 percent of 12th-graders had used marijuana at least once, up from 33 percent in 1992.
• More than one in five eighth-graders had used inhalants (aerosols, glues, solvents) at least once in their lives.

An accumulation of negative behaviors is the best way to spot a child who may be using drugs.

Isolation
Example: Scott grew up doing his homework at the kitchen table. Now he holes up in his bedroom each night after dinner and stays out of sight until morning.

Kids who use drugs want to hide the effects, the smell and the incriminating paraphernalia. They also want to avoid direct questions about where they've been and what they've done. The easiest way to do this is to stay out of sight.

Personality or attitude changes
Example: Andy's grades slipped last year; you chalked it up to too many activities. This year he seems to have lost the pride he once held in getting good grades.

Changes in personality or attitude may be gradual, such as a decreasing interest in school. You may also witness sudden mood swings. Both can indicate possible drug use. So can irritability, anger and euphoria.

Physical changes
Example: Amanda is losing weight and looking gaunt in the face, and she doesn't seem to be as concerned as she once was about how she dresses.

Difficulty with concentration, loss of coordination, weight loss and an unhealthy appearance are all signs of possible drug use.

New friends
Example: Janice has stopped seeing her best friend, and you notice a new girl picking her up each day before school. They seem to be leaving earlier than necessary.

Making new friends certainly doesn't mean a child is involved in drugs, but a sudden or wholesale exchange of one set of friends for another does indicate something drastic has changed in the child's life, and it may be drug use.

The U.S. Department of Education publishes a booklet entitled "Growing Up Drug-Free: A Parent's Guide to Prevention." A leading expert offers some approaches that may be helpful.

If you suspect drug use, voice your suspicions.
Talk to your child when he or she is sober and you're calm — and avoid direct accusations. It's hard, but avoid that angry "How dare you disappoint me" attitude. That will just drive the kid away. And if you later discover that the child was not using drugs, and you've made these accusations, you lose trust.

A major dilemma for many parents is whether to search a child's room. In a normal parent-child relationship, there has to be trust. You can give the child privacy in his or her room, but that doesn't mean you never walk in. If you have suspicions about drug use, talk to the child and ask for reassurance that no drug use is occurring. If you feel you must search the room, do it with the child present.

Ask what's been going on in the child's life.
Talk to your child without sounding accusatory. If you push the drug question too quickly, you'll get an argument. Start by asking how things are in general. Then make it clear what's bothering you. Maybe you've smelled something or you've seen grades drop or there's been some change in behavior.

If you encounter reluctance to talk, enlist help.
If the child won't talk and you're concerned about falling grades or other negative signs, be up-front with the kid. Tell the child you're concerned about the behavior you've witnessed and that you'll be talking to other people, such as teachers and the school's guidance counselor.

These conversations don't have to focus on your drug suspicions. Just ask these people if they've noticed anything unusual about your child's behavior. If you hear anything from them that deepens your suspicions, bring that information back to your child. If you don't get a response from the child, seek professional help. Your family doctor will probably have names of people to contact. Ask for referrals to professionals and organizations that the doctor has had direct experience with.

Ask yourself what could be going on in your child's life that might prompt drug use.
Looking at the pressures a child is under might help you determine what's on the child's mind or causing the changes in behavior you've witnessed. Stress in a child's life can lead to all sorts of negative behaviors, drug use being just one of them. But locating a "magic bullet" that causes a child to start using drugs is unrealistic.

Enforce discipline for any violation of house rules.
This is an important process that applies to behavior in general, not just to drug use. Generally, parents give kids more freedom as they are able to handle increased responsibility. If school grades start to slip, you may have to reinstate rules that you had eased up on, such as checking homework every night.

The same sort of structured rule system should be applied to a child who is using drugs. A child caught drinking might lose car privileges, just as he or she would lose them for coming home later than the agreed-on time. When a child doesn't uphold his or her end of a trusting agreement, back up a little on the freedom you've given. Regaining your trust is then up to the child.

Establish ways of regaining trust.
You can bring structure back into your child's life without it becoming a punishment. Treat this infraction of the rules (drug use) the same way you'd treat falling grades. Re-establish rules that will help you and your child manage his or her time and activities. Such rules may include spending more time at home, improving grades and calling in when away from home. When you feel that the child is no longer using drugs and can be trusted again, then you can ease up on the restrictions.

Have the child evaluated by a substance abuse professional.
If you think a child is lying and the evidence for drug use is strong, have the child evaluated by a professional experienced with substance abuse, but don't make this visit seem like a punishment. Stress that you want to help the child.

Many children are sure to say, "I'm not using drugs." Then what to you do? Be firm, and insist that an evaluation be done. You can make it very clear to the child that you want to trust them, but in the face of mounting evidence, you need professional help to get a fair and honest evaluation.