I am taking arthyromisin. i just had very very dark brown urine. almost like tea or dr pepper. should i go to the er or just call the dr in the mornin?

Call in the morning: If you otherwise feel fine, this can wait until you see your primary Doctor. Unless you have a very atypical emergency department near where you live, you will likely sit in the lobby for many hours if this is your only complaint.

Erythromycin-Liver i: Erythromycin in in some rare cases may may induce liver toxicity. Is the white of your eyes yellowish ? It is important to have a parallel call CMP, in which the liver enzymes and the bilirubin are shown. If you have a Dr. who has prescribed the erythromycin, please request an appointment and see him. What you must probably have is some degree of liver toxicity