I am a 45 year old male that was suffering from persistent acne. My doctor prescribed me 500mg twice a day. I only used 500mg once a day for a month. I then started opening the capsules and reducing the dosage. I now take 125mg a day and have been doing so for 5 months with good results and no side effects. I have also been taking a daily probiotic. Has anyone taken Ampicillin for longer than 5 months?