Why do so many people have low back pain?

Low back pain is a very common problem, because the lower back carries most of your weight. Four out of five adults have back pain at some time in their life.

What are the most common causes of low back pain?

Here are the most common causes of low back pain:

• Muscle strains and spasms—improper or excess lifting or twisting may cause strains or spasms of the muscles that support your back.

• Osteoarthritis—as you age, the cushioning discs between the bones in your spine become dry and hard, and the spine stiffens, leading to pain and discomfort.

• Sciatica—compression of a nerve (such as you might get from a disc that slips out of its spot between your backbones) and inflammation of a nerve cause pain to travel from your back down into a leg. The pictures below show a disc that has slipped out of the right place and presses on a nerve.

How is low back pain treated?

Most of the time back pain gets better in two to four weeks with what doctors call “conservative therapy”:

• Over-the-counter pain relievers

• The application of ice in the first 24 hours and heat on the following days

• A gradual return to normal activities

Over-the-counter pain relievers include nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen (brand names: Advil, Motrin, Nuprin), ketoprofen (brand name: Orudis KT), naproxen sodium (brand name: Aleve) and aspirin.

Aspirin can cause stomach problems and should be taken with food. If you are taking blood thinners, you should ask your doctor if it's safe to take any medicine that contains aspirin.

Acetaminophen (brand name: Tylenol) is less likely than aspirin and other NSAIDs to bother your stomach.

A gentle return to normal activities is encouraged. Strict bed rest doesn't help and can actually slow the healing process.

What warning signs should I look for with low back pain?

If you have back pain plus any of the following conditions, you should call your doctor:

• Fever

• Past use of steroids, like prednisone

• Losing weight without trying to

• Pain that gets worse or doesn't get better when you stop moving and rest

• A history of injury to your back

• Bladder or bowel problems

• Weakness in your legs

• Severe pain

• A history of cancer