DEAR DR. ROACH: After viewing an infomercial that praised the benefits of probiotics, I would like to know what you think. Probiotics have been prescribed when one is taking antibiotics to replenish the good bacteria that is lost. When taking no medication, I found that when I took one capsule (30 billion live cultures per capsule/10 probiotic strains) on a daily basis, I would get gas and diarrhea; therefore, I stopped taking them. I thought that this was the exact opposite reaction that should have occurred. Please write about the pros and cons and the reasons/necessity for taking probiotics on a daily basis. - D.A.M.