Howard, who is nursing bursitis in his left ankle, fouled a ball off the big toe of his right foot on Saturday. Phillies manager Charlie Manuel said that Howard will likely have a cortisone shot in the injured ankle on Monday.
"I think that should really help him some for the rest of the season and stuff," Manuel said. "That kind of looks like what we are going to do. After talking to him, I felt it was better to keep him from playing. If you notice, some days he runs better than others.
"I talked to him today because I wanted to play him, because the Cardinals are still playing for something, the Braves are still playing for something and [Cole] Hamels is pitching.
Howard is possibly the biggest beneficiary of the Phillies' dominance this year; they clinched the East in a franchise-best 150 games. If all goes as planned, Howard could be back in the lineup on Thursday, which means he'll miss Tuesday's day-night doubleheader against Washington.
"Just talked to the doctors and he's got some bursitis," general manager Ruben Amaro Jr. said. "So it's something I think we should treat. We'll find out more tomorrow, but I think he's going to get a shot.
"I'm not sure what they're going to shoot him with, but probably something like cortisone. And he's going to do it into the bursa sac there. That's what my understanding is. It's just gotta calm down. It's been bothering him. So we're going to try to calm it down."
Howard said he wanted to be in the lineup, but he was focused on getting healthy for the postseason.
"Distraught, completely distraught," Howard joked. "The goal is to be out there and be able to play, but the focus is towards October and being healthy for October."