Neostrata Gel Plus Aha 15

Pros: works! good price.
Cons: stings a bit. doesn't work well under makeup.

This stuff is absolutely the BEST solution for acne without a prescription. I'm in my 30's and have had cystic acne since my early 20's. I took accutane at the age of 28. Post-accutane, I still had acne but less severe than before. I use the 15 AHA every night and it keeps my skin clear. If I go 2 days without it, I get those nasty cystic pimples. So if you use it, you have to be SURE to use it nightly.
It's quite potent so it will sting ALOT if you apply it to dry or irritated skin. My routine: wash face (don't scrub too much), apply favorite moisturizer (I recommend Aveeno or Eucerin), apply AHA. It will sting a little for a minute.
You will notice that the highest AHA concentration you can find in the stores is something like 6%. So you can imagine how strong 15% is!