Please read the entire question. I ve been coughing since March and I appear to be allergic to the master bedroom of my house (no carpet, no visible mold) but the cough is out of control in that room. A doc prescribed clarithromycin 500 mg for 20 days. I took for 7 to no avail, but the 7th night I took Allegra 24 hr that helped, so the next day I quit the antibiotic, missing one dose. I felt worse the next day, so started the dosing of the antibiotic again albeit much later in the day and then I decided to quit again because I read about prednisone interaction, but took a dose in the middle of the night. (All in all I missed one dose, but stretched the last two out) Last night my RA hurt, could the antibiotic be the cause, also there was massive twitching on my right side. I did have a beer float (I avoid drinking very much). I also take Prednisone (3mg a day-tapering off after 2 years, Amitiza 16mg, Leflunomide 20mg, a multivitamin and calcium w/D. How does the Clarithromycin interact with Prednison, should I quit the antibiotic? What about the Allegra, which made me seem so much better?