Is aspirin safe? Richard Pearce, Ph.D., turns to the best research available in 1985 to answer this question.
NOTE: This article was published in 1985. Though the author references several of the time's most compelling aspirin research, MOTHER EARTH NEWS recommends turning to more recent research and your physician for more answers about the safety of aspirin today.
It's in more purses, desk drawers and medicine cabinets than any other drug. It's a mainstay for headaches, fevers, arthritis, colds, cramps, aches and pains. It's the subject of countless physicians' recommendations to "take two and call me in the morning." It's acetylsalicylic acid — aspirin — and no drug in history has been taken so casually by so many for so long. But is aspirin safe?
For many consumers, recent research has elevated aspirin's status from that of a simple pain reliever to that of a potential wonder drug.
Some scientists say it may be able to prevent everything from heart attack and stroke to cataracts, gallstones and sickle-cell anemia.
But don't rush to your medicine chest just yet. For every study showing that aspirin might have newfound benefits, there's another showing new risks. Pregnant women are advised to avoid it altogether. The Food and Drug Administration (FDA) may order manufacturers to add cautionary labels to the drug, warning consumers not to give it to children with fevers because of its association — widely noted but still unproven — with potentially fatal Reye's syndrome.
Like all drugs, aspirin is a double-edged sword, and today both edges cut deeper than ever before.
Aspirin has been used for thousands of years, but only recently have scientists learned how it works at the cellular level. In 1971, aspirin was shown to inhibit production of prostaglandins, a family of hormonelike substances found throughout the body. Prostaglandins are associated with pain, inflammation and menstrual problems, hence aspirin's ability to alleviate pain, inflammation and mild menstrual cramps.
But it's been the suggestion that aspirin may be useful in preventing heart attacks that has thrust the drug into the medical limelight. In a half-dozen studies from 1974 through 1980, more than 10,000 people who had had one heart attack took aspirin to see if it could significantly reduce their risk of another. Half the participants took one to five aspirin tablets a day for up to three years. The rest took a placebo. In all but one study, the aspirin users suffered fewer cardiac problems, including heart attacks, and had a lower overall death rate than those who took the placebo. But the differences between the two groups were not statistically significant. Furthermore, the largest study's findings took everyone by surprise and raised some disturbing questions.
That trial was the $7 million AMIS study (Aspirin Myocardial Infarction Study) sponsored by the National Heart, Lung and Blood Institute. Every participant in this double-blind study had had at least one heart attack. Half took the equivalent of one extra-strength aspirin tablet a day. The rest took a placebo. At the end of the three-year study, the aspirin group showed 22 percent fewer nonfatal heart attacks, but their total overall mortality rate was actually higher. Why? No one knows. The aspirin users reported twice as many cases of nausea, vomiting, constipation and peptic ulcers as the placebo takers. The reduction in heart-attack risk was not statistically significant. In fact, the only thing the AMIS project demonstrated conclusively was the all-too-familiar link between aspirin and gastrointestinal problems.
To find out "once and for all" if aspirin reduces risk of heart attack, Harvard Medical School has launched a new four-year double-blind study involving physicians themselves as the subjects. So far, 30,000 healthy physicians over 40 have enrolled. The idea is to see if aspirin can prevent first heart attacks and strokes in people who do not have cardiovascular disease. The study, the most ambitious of its kind ever attempted, should yield a wealth of information in the late 1980's — if the doctors remember to take their medicine.
Anyone who watches TV knows that aspirin can upset the stomach, aggravate ulcers and cause other gastrointestinal problems. But, like many drugs, its most hazardous side effects occur when it is used by pregnant women. An estimated two-thirds of all pregnant women use aspirin. Animal studies leave little doubt that aspirin can cause birth defects, but human studies are more ambiguous. Several European studies have implicated the drug as a cause of infant malformation, including one Finnish study that showed that mothers of infants with cleft palates had taken three times as much aspirin during pregnancy as mothers who gave birth to normal infants. But other research, including the large American Perinatal Collaborative Project, has shown no link between aspirin and any birth defects. At this writing, it's impossible to state definitively if aspirin causes human birth defects, but caution is certainly advised.
Aspirin appears to reduce the effectiveness of interferon, the body's natural antiviral protein. Laboratory studies show that when living cells are bathed in an aspirin solution, they promptly lose their ability to use interferon, and are killed by invading viruses. In these experiments, aspirin reduced the antiviral effect of interferon by a factor of 1,000. This finding means that people who take aspirin for colds may prolong the life of the cold virus and spread their colds to more people.
Aspirin may also cause a temporary but dramatic decrease in serum complement, a family of proteins necessary to defend successfully against viruses and bacteria. Healthy individuals, apparently, can cope with this temporary loss of protection, but some doctors worry about aspirin use by people already deficient in serum complement because of ongoing or recent infection.
Aspirin and other antipros-taglandins may also interfere with the immune system's ability to distinguish between disease agents and the body's own cells. Aspirin seems to interfere with the activity of suppressor T lymphocytes, which normally check excess antibody production. Nobody knows whether this possible action of aspirin may trigger such autoimmune disorders as Guillain-Barré syndrome or multiple sclerosis; however, quite a few cases of Guillain-Barré followed the U.S. swine-flu immunization program a few years ago. Did those who developed Guillain-Barré take aspirin to relieve the muscle soreness associated with their flu shots? Nobody knows. But a strikingly similar pattern links aspirin use by feverish children to Reye's syndrome. At present, there is no hard evidence that aspirin-related decreases in viral defenses do any harm.
But the implications of all the new research into the drug's effects are clear: Aspirin is not for everyone. It clearly provides relief from pain and inflammation. It may reduce risk of cardiovascular disease. Recent reports have suggested that it may be of value in the management of cataracts, sickle-cell anemia, gallstones and food allergies. And if aspirin is used cautiously and only when appropriate, it will probably remain a reasonably safe way to deal with some of life's more painful moments.
But for each of its many benefits, aspirin can also do harm when used by the wrong person at the wrong time.