Q. Since 1979 I've been taking laxatives to relieve constipation. At first it was one or two tablets every week or so, but now it's up to seven to nine tablets a night. I've tried to stop taking them, but without success. What can I do to break this habit and become more regular on my own? A. Yours is not an easy problem to solve. You've developed laxative dependence, a condition caused by prolonged use of stimulant-type laxatives. Your intestines have lost their natural ability to bring about normal bowel movements, and now depend on increasing use of laxatives to work. Like muscles that have become flabby through lack of exercise, your intestines have become "flabby" after years of artificial stimulation.

I recommend avoiding extended use of stimlant-type laxatives, which contain one of the following ingredients: bisacodyl, cascara, castor oil, danthron, phenolphthalein or senna. (Remember to read labels carefully, especially for warnings against improper use.)

It's too late for the best remedy against laxative dependence -- prevention. Preventive measures, such as regular bowel habits, high fiber diets, plenty of liquids and exercise, help keep the intestines regular and free of the need for long-term laxative use.

You should see your doctor to make sure you don't have an intestinal disorder, and to help you taper yourself off laxatives, which may take weeks to months. The tapering process involves:

* "Retraining" exercises to help establish regular bowel habits.

* High fiber supplements, such as psyllium-containing laxatives.

* Stool softeners, mineral oil, or both.

* Temporary use of enemas in resistant cases.

* Q. What is trichomoniasis? Can you get it even if you're not sexually active? Why aren't you supposed to drink alcohol when taking medicine (Flagyl) for it?

* A. Trichomoniasis, often called "trick," is an infection caused by a tiny, single-celled organism. It's one of the most common sexually transmitted diseases. Although unlikely, it's also possible to get a trichomonas infection without having sex. Fortunately, other than causing some annoying symptoms, it usually doesn't lead to serious complications.

Trichomonas can't live outside the human body. In women it resides in the vagina and the urethra, and in men the urethra and prostate gland. It may not produce any symptoms, and in men this is generally the case. In women, however, trichomonas commonly causes a vaginal infection with an unpleasant-smelling discharge and local irritation.

Treatment is usually effective, either with a single 2,000 milligram dose of metronidazole (Flagyl), or 250 milligrams three times a day for a week. All partners should be treated, whether or not they have symptoms. This medicine should not be taken early in pregnancy. Also, Flagyl doesn't mix well with alcohol, and can give you a bad reaction (headache, vomiting, stomach cramps) if you drink on days you take the medication.

* Q. For the past three years, I've gotten severe pains on the left side of my face from trigeminal neuralgia (tic douloureaux). I'm 64 and have been thinking of having the nerve cut if my doctor doesn't come up with something that will kill the pain. Is there anything else I can do?

* A. Trigeminal neuralgia refers to pain in one of the major nerves of the head, the trigeminal (meaning three-fold because it has three main branches). This condition is also called tic douloureaux, meaning painful spasms.

Trigeminal neuralgia causes excruciating shock-like attacks of pain in the jaw and cheek region of one side of the face. The attacks last seconds to a minute or so. Certain actions, like chewing or touching certain "trigger zones" when shaving or applying make-up, may spark an attack.

You didn't mention which medicines you've tried, but carbamazepine (Tegretol) and phenytoin (Dilantin) usually help prevent or shorten the attacks. Baclofen (Lioresal) is a newer medicine that sometimes works if the others don't.

If medications don't help, there are two surgical procedures that may, and neither involves cutting the nerve. The first is called radiofrequency rhizolysis. In this technique, a neurosurgeon inserts a needle through the side of the face to the main body of the trigeminal nerve. A small current heats and damages the nerve, and an expected complication is loss of some feeling on the affected cheek and jaw area. In the second procedure, a neurosurgeon operates on the base of the skull to relieve pressure on the nerve. Both are delicate procedures with possible complications, so they should be tried only in cases resistant to medical treatment. Follow-Up on Medication

In response to my advice on medication tips, a reader wrote to remind me about two very useful sources of drug information -- your doctor and pharmacist. Most pharmacists and many physicians have patient education leaflets about each prescription drug you're taking. All you have to do is ask.

For each medicine you should know:

* The brand name and generic name.

* How much to take.

* How often to take it.

* Common side effects.

* Warning signs of serious side effects.

* Any special instructions about how to take it (such as with or without foods).

* What to do if you forget a dose.

* Whether it doesn't mix well with foods, alcohol or other medicine you're taking.