The Tottenham winger is a doubt for the crucial Group A World Cup qualifier against Scotland after a virus delayed his involvement in training until a session on Thursday
The Tottenham winger was unable to join up with his international team-mates due to illness earlier in the week, but took part in training on Thursday ahead of Friday's bottom-of-the-group clash.
And Coleman has reassured Spurs that he will monitor the 23-year-old's fitness closely to avoid any further setbacks for club or country.
"He came up after us, took a later flight, he was suffering for a few days with an illness, which he contracted probably Tuesday or Wednesday," Coleman told Sky Sports News. "But he's okay, got a later flight and he's at the hotel.
"We won't risk him, he's Tottenham's player. He turns up most games for us and he's been brilliant for us, but if there's any risk we won't play him.
"We've got today and tomorrow. He's with us, he hasn't trained this week, but he has had a lot of games. Sometimes it's good for players to have a little rest.
"We'll be guided by Gareth predominantly, but we're optimistic. He's here, he's with us and hopefully he'll be ready for tomorrow night."
Coleman was also quick to play down the severity of the illness, and refused to confirm whether Bale would start at Hampden Park.
"Well I wouldn't like to give too much away but he's got as good a chance as anybody else of starting," Coleman added.
"There's nothing serious. He had sickness for a few days which obviously stopped him from eating, so he didn't have enough food and enough water for him to train, certainly to the levels we expect and we need.
"It wasn't worth taking the risk, but he's okay. He's up here with the squad and hopefully will get a good night's sleep. He'll do a session today with us and is looking forward to tomorrow night like the rest of us."