New medication, new side effects

GP prescribed duloxetine to help with the 'hyperalgesia' in my left knee. Been on it for going on a week.

Why is it every medication to 'fix' problem make me drowsy, sleepy, brainfogged?

Current new side effects: Feeling dizzy, blurred vision, feeling nausea (thankfully, no vomiting) and dry mouth.

I have been told they will lessen with time. Oh gawd I hope so. Walking around feeling half asleep. feeling the room spin isn't fun.