I was prescribed ampicillin after I developed a resistance to other antibiotics. I thought once I became an adult, I wouldn't have to worry about acne, but I started breaking out when I was in my 30's. My doctor told me that adult acne is not all that uncommon.
I was just as frustrated to deal with this acne as an adult as I was when I was a teenager. I know that many antibiotics have side effects, but I think they are worth the risk for a short time if they can clear up the acne.
I take ampicillin as needed if I break out with acne. I am thankful that it works quickly and I don't have to stay on it for a long period of time.