Complex sentence: Pharmaceutical ephedrine is particularly dangerous to people with valve damage, heart problems and heart disease, but can also cause heart attacks, stroke, or death in previously healthy young adults, however there is no literature to support this.
Split into simpler sentences: Pharmaceutical ephedrine is particularly dangerous to people with valve damage, heart problems and heart disease. Ephedrine may also cause heart attacks, stroke, or death in previously healthy young adults, however there is no literature to support this.