Q: I think I may be addicted to cola drinks. Is there any harm in this?

A: My guess is that you crave the caffeine in cola drinks, not the cola itself. You can test this by drinking caffeine-free colas. If you don't notice any difference, then it's probably the cola you're after. If so, you only need to worry about whether you're getting too many extra calories, in which case diet sodas are the answer. But in case you have "withdrawal" symptoms while drinking caffeine-free colas, let me say a few words about the effects of caffeine.

The average American consumes 200 milligrams of caffeine each day -- in coffee, teas, colas, chocolate and cocoa. Caffeine is also present in some over-the-counter pain relievers, including Anacin, Excedrin and Vanquish. Depending on how it's made, a cup of coffee contains between 50 and 140 milligrams of caffeine, tea has 30 to 40 milligrams, and colas contain 35 to 45 milligrams in 12 ounces.

Because it's a stimulant, caffeine can cause nervousness, insomnia, muscle tension, tremor, rapid heartbeat and occasionally irregular heartbeat. Even though caffeine is not truly addictive, some heavy drinkers of caffeinated beverages have withdrawal symptoms if they stop their caffeine intake abruptly. These include headaches, nausea, drowsiness, nervousness and mild depression.

There has been a lot of controversy about the potential health hazards of caffeine consumption, particularly coffee drinking. Scientists have speculated that caffeine may be linked to cancer, birth defects, fibrocystic breast disease, intestinal ulcers, high blood pressure and heartbeat irregularities. Except for heart rhythm disturbances in susceptible people, most studies show no firm connections.

Although a strong case can't be made for caffeine as a health hazard, I think it's wise to limit your caffeine consumption to moderate amounts, say 200 to 300 milligrams or less a day.

Q: I hate summer. In the past few years my legs have become roadmaps of varicose veins. I've become extremely self-conscious and embarrassed about donning a swimsuit or shorts. Various leg makeup preparations didn't help. Is there anything that can be done?

A: Leg veins have a series of one-way valves inside them to keep the blood flowing in one direction -- back to the heart. When the valves don't work properly, the blood in the veins pools in the legs, under the force of gravity, causing the veins to swell and twist.

The result -- varicose veins -- affects about 15 to 20 percent of adults, women five times as often as men. In some cases they're hereditary; in others they're caused by injury to the leg or a prior bout with phlebitis, a damaging inflammation of the vein.

Besides their unsightly appearance, they give some people a feeling of leg tiredness, heaviness, aching or itching. They lend to get worse with menstrual periods and in many cases first develop during a pregnancy. The major complication of varicose veins are leg ulcers, which can occur after many years of progressive skin breakdown. There are two main treatments for varicose veins -- vein stripping and compression sclerotherapy.

In vein stripping, a surgeon removes as many of the visible veins as possible through multiple tiny leg incisions.

In sclerotherapy, which means "hardening," a surgeon injects a substance into the veins that causes them to harden and contract into scar tissue. The leg is then wrapped in elastic bandages for about three weeks.

Both techniques are about 70 to 90 percent effective, but varicose veins can return after either of them.

Q: Please explain the pain of sciatica. I understand it has something to do with inflammation of the sciatic nerve, which runs down the back of the thighs. My questions are whether or not it will heal itself, whether medication can help or whether one just takes aspirin and lives with it.

A: Sciatica gets its name from the sciatic ("hip region") nerves -- the largest pair of nerves in the body, running from the lower back and buttocks down each leg. Sciatica isn't a specific medical condition, but refers to pain in this nerve, usually due to pressure from a ruptured or slipped disc in the lower spine. Narrowing of the disc spaces between the back bones (vertebral bodies) can also pinch the sciatic nerve and produce pain.

Occasionally, sciatica is caused by a variety of other conditions, including: 1) direct injury, as in a fractured pelvis; 2) diabetes, which can cause inflammation of the nerve; and 3) an injection inadvertently given into the nerve instead of the muscles of the buttocks. In some cases, the inflammatory type of sciatica occurs for no apparent reason.

Sciatica due to pressure is a sharp, aching pain made worse by movement, like stretching, straining, coughing, bending or lifting. Sciatica due to inflammation feels like a burning or aching pain.

Treatment depends on the type of sciatica and its exact cause, which you should have diagnosed if you haven't already. The most common cause, slipped disc, is treated with bed rest, traction, pain relievers and muscle relaxants, followed by physical therapy and back exercises. Surgery or, in certain cases, disc-dissolving injections are used if the standard treatments don't work. Inflammatory sciatica of no apparent cause is treated with pain relievers, anti-inflammatory medications and antidepressants, which sometimes help in cases of nerve inflammation.