Yes, but it may have turned to morphine so may lack the level of rush you would expect.
Anyhow, check the barrel of the syringe for undissolved heroin cuts. I have noticed when I prep a syringe of dope and leave it sitting out for a few hours when I pick it up a whole bunch of cuts that had appeared to dissolve at the time of preparation have un-dissolved or become more visible. So you may want to re-filter it. But it's safe.