The Hunger (1983)
The Egyptian vampire lady Miriam subsists upon the blood of her lovers. In return the guys or girls don't age... until Miriam has enough of them. Unfortunately that's currently the case with John, so his life expectancy is below 24 hours. Desperately he seeks help from the famous Dr. Sarah Roberts. She doesn't really belive his story, but becomes curious and contacts Miriam ... and gets caught in her ban, too.