NHS Guidance: as well as avoiding all alcohol -
Duloxetine usually takes 2 to 4 weeks to work. It may take longer if you're taking it for nerve pain.
Common side effects include feeling sick, a dry mouth, headache, constipation and feeling sleepy. These side effects are usually mild and go away after a couple of weeks.
If you and your doctor decide to take you off duloxetine, your doctor may recommend reducing your dose gradually to help prevent withdrawal symptoms.
You may find you cannot concentrate properly while taking duloxetine. When you first start taking it, it's a good idea to stop driving and cycling, and avoid using machinery or tools, for the first few days until you know how this medicine makes you feel.
Why did your GP prescribe this? In the 1980s when I first began ADs for depression/anxiety, without 24 hours I would have extreme nausea - it took 8 different tablets B4 I found 1 that didn't cause this. Since then, the ADs have worked well for depression and I have an go-2 emergency med for anxiety. Is 90mg the highest dose available, I would have expected some relief by now.