Hi Jon,
Citalopram is generic for Celexa. You can read more about the medication here including side effects, interactions and other information. Under the side effects section, you can see that the shaky feeling is an unlikely but serious side effect of the medication and you should alert your doctor if you experience this. Citalopram is a selective serotonin
reuptake inhibitor-SSRI. It is possible that while Citalopram did not work for you, there is another selective serotonin
reuptake inhibitor-SSRI that will work. You didn't mention if you were taking any other medications, but even natural herbs and vitamins can affect the way a medication interacts.
The best thing to do is to sit with your doctor and look at all the options. If this medication is not working for you, it's possible that another one will work better without the side effects. Online resources are great places to get the information you need to ask all the right questions, but should never take the place of your doctor's solid medical advice.
You can read about alternate medications that are regularly prescribed for anxiety and panic attacks here in the drugs database. You can also look at alternative treatments here in the treatments database.
I hope this helps! Please stay in touch and let us know how you are doing!Vicki M