Codeine cough syrup in a hot car.

I found a bottle of Cheratussin from a prescription filled back in April. It was in the back of a friend’s car. If I wanted to keep it, just in case, would it still effective/safe?

Everything I’ve ever read on it says to store between 15 - 30 degrees (Celsius), away from light and heat. I believe the back of a car can get much hotter than that, especially in the summer. I’d toss it.