Citalopram - When does the anxiety subside?

Hi, Angie!
New or increased anxiety is a common side effect when first starting an antidepressant/anxiolytic but generally starts to improve with the first several weeks. It can take 6-8 weeks for the medication to become fully effective but you should see significant improvements before then.
If the anxiety is severe let your health care provider know because you should always report any side effects you might experience. She/he may be able to give you a short term course of a mild sedative to get you through the worst of it. Also, a temporary decrease in dosage my help your metabolism adjust to the drug more smoothly.

"How Long Does It Take For Citalopram To Work?
Sleep, energy, or appetite may show some improvement within the first 1-2 weeks. Improvement in these physical symptoms can be an important early signal that the medication is working. Depressed mood, anxiety, and lack of interest in activities may need up to 6-8 weeks to fully improve."
"Common (1% to 10% of users): Abnormal dreams, agitation, anxiety, depression, impaired concentration, nervousness"

Best regards and don't be afraid to call your doctor. I hope you're feeling better quickly.