Nelfinavir is one of several medicines, along with ritonavir, atazanavir, clarithromycin, indinavir, itraconazole, saquinavir, ketoconazole and telithromycin, that can raise the level of the inhaler's medicine in your body. For a short course of fluticasone propionate + formoterol fumarate, this is usually of little clinical importance. If you use fluticasone propionate + formoterol fumarate for a long time, be more careful. Where possible, avoid taking it together with nelfinavir.
These medicines can affect each other in a serious way. Do not start taking them together unless your doctor has said it is OK. If you already take both, do not stop either one on your own: speak to your doctor or pharmacist soon.