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

Background: Some people with multiple sclerosis (pwMS) avoid exercise due to overheating. Evidence from a variety of cooling treatments shows benefits for pwMS.

Objective: Conduct a randomized controlled trial of antipyretic treatment before exercise in pwMS.

Methods: 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).

Results: 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.

Conclusion: 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.