There are a few culprits in some mineral makeup brands that while technically non-comedogenic can often irritate sensitive skin. Cornstarch is in a lot of them (sometimes called Zea-Mays starch in cosmetics) and is not technically a pore-clogger but acts as a food source for acne bacteria which can aggravate breakouts. Mica and Talc I have heard are often irritating as well and are both super common. Also mineral oil is often included (it's in most BareMinerals products) and although it's technically non-comedogenic because the skin doesn't absorb it, some people find it clogs them anyways. Personally I have no problems with certain highly comedogenic ingredients (SLS, coconut oil, etc) but the mineral oil in BareMinerals made my acne worse for years. I know there was also Ethylhexyl Palmitate (rated a 4/5 on the comedogenic ingredients list) in my very expensive Elizabeth Arden loose powder.
That being said, mineral makeups can be great- theres a million out there, and you may just want to narrow down the list by figuring out which particular ingredients are breaking you out. Always check the ingredients regardless of whether it says non-comedogenic or not (the regulations for that label are slim to none). One of those is probably the culprit!
Also, remember that acne doesn't get better overnight, and makeup rarely improves acne, it usually is just neutral- non pore clogging, non-irritating, and causes no new breakouts. If your old makeup was super comedogenic switching to mineral powder may be a great step, but it could take a while to see a change.
Edited by MarnieMarie, 27 February 2013 - 12:07 AM.