A randomized controlled trial of oral antipyretic treatment to reduce overheating during exercise in adults with multiple sclerosis

Some people with multiple sclerosis (pwMS) avoid exercise due to overheating. Evidence from a variety of cooling treatments shows benefits for pwMS. Conduct a randomized controlled trial of antipyretic treatment before exercise in pwMS. Adults over age 18 diagnosed with relapsing–remitting MS reporting heat sensitivity during exercise were randomly assigned to one of six sequences counterbalancing aspirin, acetaminophen, placebo. At each of three study visits separated by ≥ one week, participants received 650-millograms of aspirin, acetaminophen, or placebo before completing a maximal exercise test. Primary outcomes were body temperature change and total time-to-exhaustion (TTE), secondary outcomes were physiological and patient-reported outcomes (PROs). Sixty participants were enrolled and assigned to treatment sequence; 37 completed ≥ one study visit. After controlling for order effects, we found that body temperature increase was reduced after aspirin (+ 0.006 ± 0.32 degrees Fahrenheit, p < 0.001) and after acetaminophen (+ 0.31 ± 0.35; p = 0.004) compared to placebo (+ 0.68 ± 0.35). TTE after aspirin (331.6 ± 76.6 s) and acetaminophen (578.2 ± 82.1) did not differ significantly from placebo (551.0 ± 78.4; p’s > 0.05). Aspirin benefited all secondary outcomes compared to placebo (all p’s < 0.001); acetaminophen showed broadly consistent benefits. These results support antipyretic treatment as effective for reducing overheating during exercise in pwMS and failed to support antipyretics for increasing TTE in the context of a maximal exercise test. Benefits were shown for physiological markers of exercise productivity and PROs of fatigue, pain, and perceived exertion.