Is it safe to drink protein shakes if i am allergic to soy?

No: You should stay away from anything that has soy if you are allergic to it; certainly not a protein drink which is most likely loaded with soy. You should carefully read the labels and look for drink that has no soy in it.

No: If the protein shakes contain soy, or are manufactured in a plant where soy is processed on the same equipment, the the shakes are not safe. You want to look for shakes made with just whey protein.