I've had some of these in my desk at work and at some knock off brands in my purse. I have used them in the past with no problems - and haven't used them frequently in some time. Yesterday or the day before, I used one of these from my drawer at the office - and then when I got home, I found that I had broke out with a cyst up on my forehead (I never, ever breakout on my forehead) and then about an hour later, another cyst on my chin. Two complete separate areas. The only thing I could think of (besides hormones) that had changed in my regimen with my skin was I had used one of these sheets (and I dab them all over my face, mostly my forehead that gets shiny). I'm guessing that these caused me to suddenly break out - I have had clear skin for months (on Dan's acne products) and haven't had cystic acne in ages - even hormonal around the time of my period. This was very out of the blue. I got to looking after realizing the only different thing I'd done was use these sheets - and looked if there was a possible expiration date? Since I have used these in the past with no issues at all. I couldn't find any expiration date on the item itself, but after googling - I found some packages for sale (of these exact ones) wrapped in their original plastic (like if they come straight from the factory) and they DO - indeed have expiration dates! They say "SHELF LIFE: 3 YEARS". So be aware of how old your absorbing sheets/blotting sheets are. Mine had a manufacturing date of 2009 and another from 2011. Both expired by their expiration date. They do contain mineral oil - and I tried to research if that expires, but most sites said "No" because of how processed it is. Either way - these items DO have a shelf life - just be aware. I believe this is what broke me out suddenly.