Fowler, 30, will be the designated hitter on Friday and then play in the outfield on Saturday.
"He just has to be honest with us," Maddon said. "The deal with Dex is to be absolutely frank and honest with us about how he feels."
Maddon expects to get an update after Saturday's Minor League game, then the Cubs will decide the next step.
Even if Fowler cannot play, he still plans on going to San Diego for the All-Star festivities. This is the first time he's been named to an All-Star team.
"It's reality," said Fowler, who was batting .290 in 64 games and has provided the spark at the top of the lineup. "I think my health is more important. If I can't play, obviously, I want to go.
"It's a long season. You don't want it to occur again. You want to be smart about it."
Fowler is one of seven Cubs named to the NL All-Star team, along with Anthony Rizzo, Ben Zobrist, Addison Russell, Kris Bryant, Jake Arrieta and Jon Lester.
Fans can vote for the 2016 Esurance MLB All-Star Game Final Vote until 4 p.m. ET on Friday. The winners, as chosen exclusively by online fan voting totals, will be announced during a Final Vote-themed telecast of "MLB Now" featuring commentary from political analyst Jeff Greenfield, live on MLB Network and MLB.com from 4-5 p.m. ET. MLB Network will provide extensive coverage across all of its studio programming during the Final Vote, including interviews with the candidates, frequent updates, heat maps indicating the cities where votes are being cast for each candidate, news on player and club campaigns and a running countdown clock leading up to the announcement.
Baseball fans have cast nearly 600 million online votes for Final Vote candidates since the program's inception in 2002. In addition to MLB.com and the official club websites, fans can use their mobile devices to cast votes at MLB.com/vote or via text message. To receive the ballot, text the word "VOTE" to 89269. To vote for a specific player, fans can text their choice to 89269. EXAMPLE: Text "A3" to vote for AL Player 3 or "N3" to vote for NL Player 3. Message and data rates may apply. Text "STOP" to end and "HELP" for information. Mobile voting in Canada also is available and fans should text their choices to 101010.
For the fifth consecutive year, the Final Vote will include social balloting, as Twitter support for the 10 candidates over the last six hours of balloting will count toward their vote totals. From 10 a.m.-4 p.m. ET on Friday, any tweet that includes a designated player hashtag will be tabulated as part of the official vote total used to determine the winners.
On Tuesday, July 12, watch the 2016 All-Star Game presented by MasterCard live on FOX, and during the game visit MLB.com to submit your choice for the Ted Williams Most Valuable Player Award presented by Chevrolet via the 2016 MLB All-Star Game MVP Vote. The 87th All-Star Game, in San Diego, will be televised nationally by FOX, in Canada by Rogers Sportsnet and RDS, and worldwide by partners in more than 160 countries via MLB International's independent feed. ESPN Radio and ESPN Radio Deportes will provide national radio coverage of the All-Star Game. MLB.com, MLB Network and SiriusXM will also provide comprehensive All-Star Week coverage. For more information, please visit allstargame.com.