My dog accidently ate an Advil, Is this dangerous for him?

Yes take him to the vet. Ibuporfen can be toxic to dogs.

Yes, especially if this is a small dog. A 200 mg tablet can be fatal to a small dog.

I’ll be the third vote for yes.

How much does your dog weigh?

My 25 pound dog dug a pack of 12 out of my back pack (bad me for leaving it on the floor) and survived to tell the tale. The worry was that she would sustain kidney or liver damage. Thankfully she did not. She was staggering around for a while though.

So it depends on how much the pup ate and how big it is. One might be a problem for a chihuahua but probably not for a lab.

my dog weighs 85 pounds, he is a german sheperd

I really do not think 1 advil is going to have any effect. But keep an eye on him just in case.