Cedeno said he lost weight and felt dizzy from the sinus problems. Houston manager Bo Porter said the 30-year-old also experienced some vomiting.
"I was extremely anxious to get him back," Porter said. "When you're dehydrated and dizzy, that can stay with you for a few days, even after the medicine and treatment wears off. So I wanted to see Ronny move around and be 100 percent for a few days before we brought him back."
The Astros exclusively faced right-handed starting pitchers against the Royals, and Cedeno is hitting just .103 against righties this season. He had a healthy .464 average off southpaws entering Friday.
Cedeno went 1-for-3 in the loss, lining a hit off A's starter Tommy Milone to continue a two-out rally in the fifth inning and later scoring on a Jose Altuve single.
Dominguez missed Wednesday's 3-1 win against Kansas City with a sore left quadriceps, but Porter said the third baseman could have played, if necessary.
"It was a planned two days rest," Porter said. "We gave him that day, because we had Thursday off and wanted to help him heal faster, give him a game to regroup and recover. He's healthy and ready to go."
Dominguez hit a solo home run Friday to ignite a five-run fifth inning and now has five home runs in his last 11 games.
"I'll just keep getting treatment and it's something I can keep playing through and it's not a big deal," he said. "It's just tight. It might not go away right away, but I'll continue treatment and eventually it will go away."
Brian McTaggart is a reporter for MLB.com and writes an MLBlog, Tag's Lines. Follow @brianmctaggart on Twitter. Chris Abshire is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.