QUESTION: Both my mother and I are taking the flu medicine amantadine. She takes just half of my dosage. Is she getting protection? I'm 45 and she's 68. - B.E.

ANSWER: She very probably is. Healthy younger adults take 200 mg of amantadine daily to ward off flu and its symptoms. Those 65 and older get by better on only 100 mg, since older bodies don't get rid of the drug quite as easily. Larger doses may cause some elderly patients to have side effects, like light-headedness and insomnia.QUESTION: My drug inhaler for asthma works wonders for me. The only thing is I can see some spray coming out of my mouth when I depress the plunger. Is this expected? Am I wasting it? - C.P.

ANSWER: You're not only wasting it, you're not getting the drug down to the breathing tubes efficiently. Mist shouldn't escape.

A little practice will help. You should have had instructions with the unit. Hold the inhaler loosely with your thumb on the bottom, middle and index fingers on top. Grip the business end with your teeth. Don't close your lips around it. Take a slow deep breath, activating the plunger as you are doing this. Inhale for a few seconds, then hold your breath for five more seconds, and finally, exhale slowly. This gets the medicine deep into the breathing tubes for maximum effect.

You didn't mention the name of the inhaler, but they all work the same basically. I'll bet yours has one of the beta agonist drugs, like terbutaline, in it. When you get the mechanics down pat, you'll like the results even more.

QUESTION: Can you explain about flu shot timing, and why last year my doctor didn't want me to have mine. I came back from vacation in mid-February. I made sure I went in for it early this year, but I think many people would like to know about timing. - Mrs. C.H.

ANSWER: The earlier jump you get on the flu season the better. Mid-October is not too early, and mid-December is not too late. Beyond those times, you get into gray areas.

It takes at least two weeks before any flu antibodies appear in the blood from a flu shot. Those protective antibodies last from three to six months. Peak flu season is January and February. This is why mid-February can be late for getting the protection. Getting it after mid-February last year would have yielded marginal protection at best. For those in this predicament, the drug, amantadine, offers some degree of protection. (See earlier item today.) The ideal time for flu shots is from mid-October to mid-December.

QUESTION: My abdominal aorta has a bulge (aneurysm?). Is it of a size OK to just watch, which is my doctor's view? Is it safe to do so? - Mrs. L.T.

ANSWER: The danger from these bulges in the aorta wall is, of course, of a bursting. That's frightening to contemplate. Nevertheless there must be rules to guide doctors. So treatment hinges chiefly on size of the bulge. You don't give me your aneurysm size.

The accepted rule says that if it's larger than 6 centimeters in width, it is safest to operate and repair it. One less than 4 centimeters can be watched. Between 4 and 6 centimeters is a gray area so far as treatment is concerned.

"Watching" entails checks (often ultrasound) every three or six months. This rule is overridden by complicating factors, like high blood pressure, age or general health.

Dr. Donohue welcomes reader mail but regrets that, due to the tremendous volume received daily, he is unable to answer individual letters. Readers' questions are incorporated in his column whenever possible.