A few questions about aspirin

Aspirin may have been the only pain reliever your parents kept in their medicine cabinet, but it's no longer the first choice for many. However, it could lower the risk of heart attacks.

No. Doctors recommend daily aspirin only for people who have an increased risk of heart attacks and strokes, and women may not benefit as much as men.

• When you have a headache or sore muscles from gardening, aspirin relieves the misery by blocking production of hormone-like substances called prostaglandins.
• In addition to sending pain signals to the brain, prostaglandins cause blood platelets to bunch together and form clots.
• Because aspirin blocks the formation of clots in arteries, doctors have been recommending daily aspirin as preventive therapy to patients at high risk for heart attacks since the 1970s.
• Since then, aspirin has saved many lives. A 2002 analysis of 287 studies found that aspirin reduces the risk of heart attacks, strokes and death by about 25 percent.
• However, doctors don't tell all of their patients to pop an aspirin with their morning juice, because the little white tablets are not entirely benign. Aspirin blocks prostaglandins that protect the stomach lining, so some people who take it regularly develop ulcers and stomach bleeding.
• Furthermore, certain people — especially women — may not gain as much heart protection from aspirin as doctors once thought.
• In one major study of 40,000 women 45 and older, there was no overall difference in the number of heart attacks or the risk of dying of any form of cardiovascular disease between those who took 100 milligrams of aspirin every other day for 10 years and those who took a placebo for 10 years.
• Aspirin users did have 17 percent fewer ischemic strokes, the most common type, which are caused by blocked arteries in the brain. However, they had slightly more hemorrhagic strokes, which are caused by bleeding in the brain.
• Furthermore, women in the aspirin group were 40 percent more likely to develop stomach bleeding.

Yes. Aspirin does not protect everyone who takes the pills from having heart attacks.

• Some people have a condition called aspirin resistance. Imagine two groups of people who have high cholesterol, high blood pressure and other risk factors for heart attacks. The people in one group take aspirin every day, while the others do not. Over time, there will be about 25 percent fewer heart attacks among members of the aspirin group.
• While that's valuable protection, it's far from a guarantee. Aspirin prevents clots in the arteries — the culprit behind most heart attacks — so why isn't this drug even more powerful?
• There are a number of reasons why aspirin may fail to prevent heart attacks. For example, taking ibuprofen or other anti-inflammatory drugs at the same time blocks aspirin's effect on blood platelets.
• What's more, some people are born resistant to aspirin's anti-clotting effects. A recent review estimated that about one person in four is aspirin resistant.
• The true number could be higher or lower, since there is not yet an agreed-upon definition of the phenomenon. Even if you have aspirin resistance, though, the drug will still work as a pain reliever.

If you are at risk for a heart attack, talk to your doctor about possibly taking aspirin as a preventative measure. Like with any medication, there is always risks involved. However, the evidence has piled up over the decades to suggest that the benefits of aspirin outweigh the risks, especially if you are prone to heart attacks.