Yes, but there’s a catch.

A study published in 2001 by exercise physiologist William J. Evans of the University of Arkansas for Medical Sciences and his colleagues showed that both ibuprofen and, to the researchers’ surprise, acetaminophen (Tylenol), blocked new muscle synthesis after intense weight training exercise.

Evans’ group studied 24 men in their twenties and divided them into three groups, one that got ibuprofen, one that got acetaminophen and one that got placebo, a dummy drug, after an intense weight workout of the legs – to the point of exhaustion. The drugs were given at doses of 1,200 milligrams a day for ibuprofen and 4,000 milligrams for acetaminophen. The researchers also took muscle biopsies – small samples of muscle tissue – before and after the exercise bout and did numerous other tests.

They found that both ibuprofen and acetaminophen suppress the body’s normal response to muscle damage (and thus repair) after exercise. Although the men getting placebo had robust levels of protein synthesis in muscle tissue after exercise, the two groups getting drugs did not. The fact that ibuprofen inhibits muscle synthesis was not a surprise because the inflammatory process is involved in muscle repair and ibuprofen blocks the inflammatory reaction. But acetaminophen is known as a painkiller and fever-reducer, not as a direct inhibitor of inflammation.

So, should you skip the over-the-counter painkillers after a tough strength-training workout? Probably, if you can stand the muscle soreness and really want to bulk up.

On the other hand, even people who routinely take ibuprofen to control pain, such as those with chronic arthritis, can build muscle mass very well, notes Dr. Ronenn Roubenoff, an associate professor of medicine and nutrition at the Friedman School of Nutrition, Science and Policy at Tufts University. So far, he says, people with rheumatoid arthritis seem to “do as well or better than healthy people not taking” ibuprofen in terms of muscle protein synthesis. Perhaps the difference in findings comes from studying people after one hard exercise bout versus muscle building over time.