I was prescribed amoxicillin for a throat infection for about a week, but one of the side effects turned out to be a clearing of my acne. However, amoxicillin isn't really prescribed as an acne treatment because it is a broad-spectrum antibiotic, meaning it will kill most of the bacteria in your body, good or bad. Minocycline and doxycycline are more commonly prescribed for acne.
Bottom line: it does work, but go ask your dermatologist for something less aggressive. Also, it is important to note that antibiotics, no matter what kind, are never a long-term solution for acne. Your dermatologist will help you develop a regimen that will probably consist of a combination of retinoids, antibiotics, and benzoyl peroxide.