Store cough syrup in the refrigerator?

Hello friends,

My doctor prescribed me cough syrup for a tickly cough. It does its job. I drank it whenever I had a coughing fit, and I've often seen, especially on social media, that most people store their opened cough syrup in the refrigerator, which is normal for medications. So, no sooner said than done, I stored my cough syrup in the refrigerator overnight, and this morning, with my daily coughing fits, I had to drink double the dose because one sip wasn't enough. So I'm wondering, does the active ingredient in the cough syrup become weaker if you store it in the refrigerator?