Research over the last 30 years has shown that aspirin helps prevent heart attack, stroke, and colon cancer. There's new evidence that aspirin may help control migraine headaches, Alzheimer's disease, and cataracts. Medical experts say we haven't even begun to realize the potential of the familiar white pills, which cost mere pennies apiece.
No drug is completely safe, and aspirin is no exception. It can irritate the stomach's delicate lining, causing heartburn, ulcers, and internal bleeding. In rare cases, aspirin can lead to bleeding in the brain, and doctors also think aspirin may contribute to Reye's syndrome, a childhood disorder characterized by brain and liver damage. Aspirin is a blood thinner and can worsen bleeding during surgery and childbirth.
One bottom line assessment: If it were invented today, aspirin would probably have to be prescribed by a doctor.
Although other over-the-counter pain-killers (like ibuprofen and acetaminophen) can relieve pain with fewer side effects, only aspirin appears to have long-term cardiovascular and anticancer benefits.
But aspirin also suffers from an identity crisis.
Because of the Reye's syndrome concern, most younger adults have been raised on acetaminophen (Tylenol is the most common brand).
"My impression is there's a generation of individuals who have grown up assuming that other compounds have completely replaced aspirin," says Dr. Carl J. Pepine, codirector of the division of cardiovascular medicine at the University of Florida. "Ask a flight attendant for an aspirin and she may bring you Tylenol. We're trying to educate people that the simple aspirin is worth keeping around for reasons that could save their lives."
Most of aspirin's beneficial effects can be traced to its effect on prostaglandins, substances that regulate many activities in the body, including uterine contractions, elasticity of blood vessels, and the functioning of blood platelets that help stop bleeding. Prostaglandins also turn up when germs invade the body or when injuries lead to pain and inflammation.
By reducing prostaglandin production, aspirin short-circuits the body's ability to clot blood, generate pain, or develop inflammation. (Of course, too much of any of these effects would be dangerous, which is why doctors insist that aspirin be treated with respect as a powerful drug.)
Heart attack and stroke. Most doctors now agree there's plenty of sound evidence that aspirin helps the heart. One study, which included 17,000 patients at 417 hospitals around the world, showed that aspirin reduced the death rate by 23 percent if taken as soon as heart attacks were suspected. In a Harvard University study of 88,000 nurses, those who took one to six aspirin tablets a week experienced about 25 percent fewer heart attacks than those who didn't.
Though aspirin may increase risk of the less common hemorrhagic stroke (bleeding in the brain), it helps prevent so-called "mini-strokes" caused by clotting that stops blood from reaching the brain. Two Canadian studies found that taking a daily aspirin reduced by half the risk of death and stroke in people who had experienced a mini-stroke.
Alzheimer's disease. The anti-inflammatory properties of ibuprofen and aspirin also might reduce mental decline in old age. A 1995 study at Johns Hopkins Alzheimer's Disease Research Center found that patients who took aspirin every day showed less decline in their speaking and spatial recognition than those patients who didn't take aspirin.
The National Institute on Aging (NIA) and Johns Hopkins University discovered that people who took regular doses of ibuprofen cut their chances of developing Alzheimer's in half. Aspirin yielded a 25 percent reduction. Because of these findings, scientists now think Alzheimer's might be impacted partly by inflammation in the brain.
"There's growing evidence that people with arthritis (who take a lot of anti-inflammatories, such as aspirin) seem to have a lower risk of developing dementia," says Dr. E. Jeffrey Metter of the NIA.
Still, Dr. Metter and his peers stop short at suggesting a daily aspirin or ibuprofen for prevention of Alzheimer's. If you have a strong history of Alzheimer's in your family, the best advice, he says, is to discuss the issue with your doctor.
Migraines. Researchers aren't sure what causes these crippling headaches, but they know that just before migraines strike, the arteries in the brain constrict, reducing blood flow. Aspirin may help reduce the frequency of migraines because it thins the blood. In the Physicians' Health Study, doctors who had migraines experienced 20 percent fewer headaches when they took a daily aspirin.
"Still, nothing very convincing has been done," says Dr. Robert Kunkel, president of the National Headache Foundation and a member of the headache center at The Cleveland Clinic Foundation.
Colon cancer. Aspirin, along with a high-fiber diet, might help cut your chances of getting colon cancer, the nation's leading cancer killer among nonsmokers. An American Cancer Society study found that those who took aspirin at least 16 times a month were about half as likely to die of colon cancer as nonusers.
Aspirinlike drugs also prevent chemically induced colon cancer in laboratory rats. "This whole area is extremely exciting from a research perspective," says Dr. Michael Thun, director of analytic epidemiology at the American Cancer Society. "But it's too early to recommend it for regular, preventive use."
Researchers continue to be optimistic that other benefits of aspirin will be uncovered. There's evidence that aspirin may inhibit development of cataracts and breast cancer. Researchers also are looking into aspirin's role in reducing high blood pressure late in pregnancy and low birth weight in babies.
What's the best dosage for aspirin? The answer depends on why you are taking it:
Children under age 18: Do not use unless directed by a physician. Young children are susceptible to Reye's syndrome, a very serious illness linked to aspirin use.
For protection against heart attack, stroke, and colon cancer: Not everyone should take aspirin on a regular, long-term basis. If your doctor feels it would benefit you, the typical dosage is one adult tablet every other day or one baby aspirin (81 mg) daily.
For suspected acute heart attack: Chew and swallow one adult aspirin (325 mg) immediately. If you are at risk for heart attack, talk with your doctor about aspirin before you suffer any symptoms.
For mild aches and pain: Take between 325 mg and 650 mg every four hours or 650 mg to 1,000 mg every six hours, not to exceed 4,000 mg in 24 hours. If pain persists, call your doctor.