How long for Cipro to work

I have a sinus infection and my doctor prescribed Cipro on Wednesday.  I was unable to get it filled until Thursday, during which time the infection seemed to spread to my lungs.  Since then, I have taken it regularly and been very careful about what times I take it.  Instead of getting any better, I seem to be getting sicker.  How long should I give the Cipro before calling the doctor?

[Alison L, RPh]

Usually for a sinus infection, Cipro is prescribed for 10 days—I am not sure how long the doctor prescribed for you to take it. If you started on Thursday and you are not feeling better, you should call your doctor today (Monday) or Tuesday. Tuesday would be approximately half way through the course and you should see some relief from your infection. You may not be back to normal, but the antibiotic should start to work and you should be feeling relief to a certain extent especially half way through the course. If you feel as though you are getting worse, then you should definitely call the doctor today.

[tjroden05]

If you are diabetic and have asthma and you feel that the infection is "spreading to your lungs" you should go to an emergency room as soon as possible.  I don't believe that those who are responding here are considering your entire medical history