A: Like varicose veins in the legs, hemorrhoids are enlarged, swollen veins that form either around the anus or in the lower rectum. And like varicose veins, hemorrhoids may be a byproduct of our blood vessels' constant battle against gravity to get blood back to the heart.

Experts don't fully agree on what causes hemorrhoids, but several mechanisms are probably at work. Large hemorrhoids that protrude into the anus are associated with chronic constipation, straining during bowel movements and sitting on the toilet for long periods, all of which can cause blood to pool in and enlarge pelvic veins. Inadequate fiber intake may also contribute. During pregnancy, the growing uterus can put pressure on veins, slowing the flow of blood back to the heart. With age, hemorrhoids may bulge outward because the tissues that normally hold them in place weaken.

There are two kinds of hemorrhoids: external ones, which develop under the skin around the anus, and internal ones, which occur in the lower rectum. External hemorrhoids are the most uncomfortable because they irritate and erode the overlying skin. The pain may be sudden and severe if a blood clot forms inside an external hemorrhoid. The clot usually dissolves, but it may leave excess skin (a skin tag) that itches or becomes irritated.

Internal hemorrhoids are usually painless, but they often cause bleeding. An internal hemorrhoid may also drop down and extend beyond the anus, causing itching. The problem worsens if you wipe repeatedly to relieve the itch.

Although hemorrhoids are rarely dangerous, they can be a painful recurrent bother, as you've found.

Fortunately, most hemorrhoid symptoms improve dramatically with simple measures. Here are some things to try:

• Add fiber. Boost the fiber in your diet with high-fiber foods, a fiber supplement or both. When taken with adequate fluid, fiber softens stools and makes them easier to pass, reducing pressure on hemorrhoids and lowering the risk of bleeding, inflammation and swelling. High-fiber foods include prunes, dates, apples, pears, strawberries, broccoli, Brussels sprouts, carrots, peas, spinach, legumes (for example, baked beans or kidney beans), bran cereals and oatmeal. Fiber supplements include psyllium (Metamucil, Konsyl, Perdiem), methylcellulose (Citrucel), calcium polycarbophil (FiberCon, Fiber-Lax, Mitrolan) and wheat dextrin (Benefiber). Fiber can cause bloating or gas, so start slowly, and gradually increase your intake to 25 to 30 grams of fiber per day. Increase your fluid intake at the same time.

• Exercise. You can stimulate bowel function with moderate aerobic exercise, such as brisk walking 20 to 30 minutes a day.

• Go when you have to go. When you feel the urge, go to the bathroom immediately; don't wait for a more convenient time. Stool can back up, leading to increased pressure and straining.

• Take sitz baths. You can often relieve itching, irritation and spasm of the sphincter muscle with a warm water bath for the buttocks (sitz bath). Sit in a few inches of warm water in your bathtub or in a small plastic tub that fits over a toilet seat. Try a 20-minute sitz bath after each bowel movement and at two or three other times during the day. Afterward, gently pat the anal area dry; don't rub or wipe hard. You can also dry the area with a hair dryer on a cool setting.

• Try over-the-counter creams. These can temporarily soothe pain, irritation and itching. Creams and suppositories containing hydrocortisone are also effective, but don't use them for more than a week at a time, because they can cause the skin to get too thin. Witch hazel wipes (Tucks) are soothing and have no harmful effects. A small ice pack placed against the anal area for a few minutes may also help.

Occasionally, hemorrhoids can't be managed with conservative treatments alone, either because the symptoms persist or because an internal hemorrhoid has slipped down into the anus. If symptoms continue for more than a few days despite your efforts to relieve them, call your doctor. He or she can confirm that you have hemorrhoids, rule out other conditions and recommend an appropriate treatment, such as surgery, to remove or shrink hemorrhoids.

Unfortunately, some patients are too embarrassed to talk about hemorrhoids and suffer needlessly. The sooner you take action in treating hemorrhoids, the sooner you'll be sitting comfortably again.

HARVARD MEDICAL SCHOOL ADVISER