If an individual is shooting up like beta-blockers, including tamsulosin or doxazosin, to treat high pressure or to treat an enlarged prostate, pressure could also be too low. However, some physicians may prescribe Filagra with an alpha-blocker but at a lower dose. The effect of Filagra oral jelly is also affected if used with ketoconazole or itraconazole which are antifungal medicines