Q. My 16-year-old son does not respect me. In fact, he doesn't respect any authority. He is on drugs, has stolen a bicycle from the neighbor's garage and signed his father's name to a check.

Unfortunately, his father doesn't say anything, even when he blatantly disobeys. Things have become so bad that I have asked my husband for a separation, but I'm still worried about the child.

What can I do to help him? I have suggested to my husband that we get professional help, but he is not convinced.

A. When anyone in the family has a problem, everyone is affected, and so is every relationship. Getting separated may--or may not--make you happier, but it isn't going to make a drug problem disappear. In fact, it might compound it. Your child would learn that running away is the answer, which is what he's doing with drugs.

What he needs now is the example of parents who try to work out their own problems so that he has the heart to work on his own. And this means marriage counseling.

He also needs you to understand the phenomenon of today's drug scene, so you can help him better.

Many children experiment with drugs, some as early as fifth or sixth grades, but 15 is the peak age, according to Dr. Robert L. DuPont, head of the American Council on Marijuana.

Drugs are very seductive, especially in adolescence. The chaos of hormones creates so many dilemmas that it's hard for a teen-ager to say no to a drug--alcohol or pot or something stronger--when he thinks it may help him postpone decisions, blur pain, look sophisticated and sublimate the powerful urges that seem so overwhelming.

If the experiments turn to regular use, there also may be dependency. And there's no way to predict who is strong enough genetically to remain a casual user. Certainly no one ever plans to get addicted.

Alcohol seems more dangerous to some parents; others are more alarmed by pot, which is fat-soluble and can stay in the brain for 1-3 months. Both, however, have physical and psychological effects which can be longstanding.

Pot also may lead to pills and LSD, and even to cocaine and heroin. The National Institute on Drug Abuse reports that 97 per cent of those who take uppers and downers used marijuana first and that all of the cocaine users did. This and other information is in the excellent government booklet, Parents, Peers and Pot, available for $5 from the Superintendent of Documents, Government Printing Office, Washington, D.C. 20402.

Whatever drug--or drugs--your child is using, the problem won't go away by itself. Somebody has to step in, and that first somebody is you.

Your husband probably is denying either the drug problem or his ability to do anything about it: a typical response of even the most caring parent. Those who have been in your situation say that a child usually uses drugs for 2-3 years before his parents recognize it, and then it's usually the mother who does.

And you can't expect your child to heal himself. By now his self-esteem is down to his socks and he thinks drugs are about all that make life bearable. He needs all the help he can get, and so do you.

Many parents have profited by meetings of Tough Love: the fast-growing self-help organization for parents of children with behavior problems. In Tough Love, it's the bathwater, not the baby, that gets thrown out. Parents share their problems, and when they can't cope, other parents step in to help. For more information, call 698-7546.

It may take more than love, tough or otherwise, to make a difference with your son. First, he has to be drug-free. For this, one good option is Straight, Inc., headquartered in St. Petersburg, Fla., for children 12 to 21 who have drug problems: mostly pot and alcohol. (The organization will open a Washington-area facility this fall.)

The 10- to 24-month program costs $2,100, plus $100 a month for board in a foster home provided by another Straight family. Compare this to the $11,000-a-month treatment can cost in a local psychiatric hospital.

The cost is comparatively low because the program is run by a small executive staff of adults, trained for 3-5 months, and a peer staff of kids who have finished the program. This is augmented by the foster-home program for "newcomers"--children in the first of the program's five phases--and for out-of-towners. Parents go down for extensive counseling one long weekend a month.

Wherever Straight operates, the program is the same--and it's never easy for anybody. Every aspect of the drug culture is challenged; security is stringent. The program follows many of the tenets of Alcoholics Anonymous, with each child earning new freedoms at his own pace.

In the first phase, kids focus completely on themselves with 9 a.m. to 9 p.m. individual and group counseling. They then go directly to their foster homes; even the yard is off-limits.

When their behavior is good enough, they move on to the second phase in which they learn to live with their own families, become "oldcomers" and assume responsibility for a "newcomer." In the third phase they go back to school or to work, but return directly to the Straight program when finished. In the fourth phase they have a couple days off weekly and can go out--with written permission from Straight--to something like a movie with their parents. The fifth phase gives more time off and more responsibility in the program. If their behavior reverts in any way, they are sent back to prove themselves again.

Parents also have extensive duties, including rap sessions and foster-care responsibilities if they live in the area. Family rules are strict.

If nine months or more of this life sounds overwhelming, think about a lifetime of loving an addict and all the tragedy this will spell.

For more information about Straight, Inc., call 476-3760, or learn about it through the 3-5 p.m. meetings Sundays at the Church of the Apostles, 3500 Pickett Rd., Fairfax, Va., or through the movie at 7:30 p.m. Wednesdays at Madison High School, 2500 James Madison Dr., Vienna, Va.

For more general information, there is PANDAA (Parents' Association to Neutralize Drug and Alcohol Abuse), which puts out a bi-monthly newsletter on pending legislation. Cost: $5, 4111 Watkins Trail, Annandale, Va. 22003.