magic bullet
1. A drug, treatment, or medical therapy that provides an immediate cure to an ailment, disease, or condition without negative side effects or consequences. Despite the amazing leaps in medical technology and knowledge, we're still quite a ways off from developing a magic bullet in cancer treatment. Beware any person or company trying to sell you a magic bullet for your health problems. If it sounds too good to be true, it usually is!
2. Something that provides an immediate and extremely effective solution to a given problem or difficulty, especially one that is normally very complex or hard to resolve. There's no magic bullet that will solve the homelessness crisis in this country.