Doctors: Marathoners' reliance on painkillers poses risks down the road
"There's absolutely a role for anti-inflammatories like Motrin, Advil and Aleve, but you have to understand when they're necessary and when you should take them, said Dr. George Chiampas, medical director for the Chicago Marathon. "And more is definitely not better."

Taking too much acetaminophen — a common mistake because it's often found in combination products — can cause liver damage. Last year, Tylenol's manufacturer lowered the recommended daily maximum dose of Extra Strength Tylenol from eight 500-milligram tablets to six to reduce the risk of an accidental overdose.

Soreness is one of the least welcome side effects of exercise, but the pain is a signal that some tissue irritation or damage has occurred, Warden said. Masking that pain can lead to a more serious injury.

By the same token, inflammation is a natural part of the healing process and speeds up tissue repair. Chemicals released at the injured site attract cells that will clean up the area and heal it, Warden said.

The inflammation response often is overzealous, Warden said, and drugs can be used to control it. "But once the inflammatory signs are gone, you don't need anti-inflammatories," he said.

Race organizers are increasingly discouraging the prophylactic use of ibuprofen because of its effect on the kidneys. At the Chicago Marathon, medical staffers won't dispense ibuprofen or naproxen on race day because the drugs could affect the gastrointestinal tract or the kidneys, especially if dehydration is a factor, said Chiampas, an assistant professor in the department of emergency medicine and sports medicine at Northwestern University's Feinberg School of Medicine. Runners who need pain relief may get acetaminophen.

"No one should be taking NSAIDs for months at a time," Chiampas said. "You're putting yourself at risk for an ulcer, for GI issues or kidney problems. If you are, you need to reassess that injury and why you are taking these."

When David Nieman studied ultramarathoners competing in the 100-mile Western States Endurance Run, he found that runners who took over-the-counter ibuprofen before and during the race had noticeably more inflammation than other runners.

Nieman, director of the Human Performance Laboratory at Appalachian State University in Boone, N.C., also found the ibuprofen users showed signs of reduced kidney function and increased oxidative stress. Afterward, the runners had the same degree of muscle damage and soreness whether they took ibuprofen or not.

"I tell runners, (the drugs) are not doing what you think and are actually hurting you by leading to mild inflammation and kidney dysfunction," said Nieman, who has run 59 marathons and ultramarathons. "Ibuprofen and heavy exertion do not mix well. I don't recommend any athlete uses ibuprofen; it's amazing how it has taken over the running community."

One recent paper, published in the Clinical Journal of Pain and funded by the makers of Tylenol, did find that Tylenol is effective for treating post-marathon soreness. Another small study reported that Tylenol improved performance in cyclists by blocking pain.

Carranza said she has heard reports of the dangers of overusing painkillers, but she loves running too much to stop.

"I know it's not good," she said, echoing a common sentiment among her fellow marathoners. "But I'd rather cover the pain and keep running. I'm addicted."

Twitter @JulieDeardorff