Mylicon given to my baby by my MIL without me knowing

I just need to rant. A friend gave me mylicon at my baby shower but I haven't used it. I just happened to look in my medicine cabinet after my MIL watched my baby. The bottle was opened and used. I'm so annoyed she gave her medicine without telling me! Yes I have it in my cabinet but I didn't buy it for my baby. I haven't noticed any side effects. I makes me so mad that she would give her medicine. I try not to take any medication.