Lyon suffered abrasions to the forearm while diving for an out at first base last week, and then developed a rash from the adhesive on the bandage, manager Brad Mills said.
"They put a bandage on it, and his arm reacted to the bandage," Mills said. "He got a rash, and it was really bothering him. It's a pretty good rash, so he went to the doctor, and the doctor gave him some stuff to calm the rash down.
Lyon (6-4) leads Houston in appearances (45) and holds (17). He has stranded all seven of his inherited runners this season, and owns a 2.82 ERA in his last 39 appearances.