This is on a hedgehog forum I often visit. But I found it relevant in the care of reptiles too I thought I'd post it. (with the authors permission of course. )

"Hey guys, I know I am pretty inactive here, but I felt that it was very important that I share this with others in case anyone else had this issue! I recently brought home a rescue that I've been caring for very meticulously for the past little while-- we've gotten his weight up, he's happier and healthier than he was when he first arrived, and I've been very pleased with his progress. He had originally been on aspen shavings, and hadn't seemed to have any problems with it, but I switched him to fleece liners anyway because that's what I prefer. Then recently, we had a long drive to make to my parents' house-- they were going to be watching him for me until his new adopter was able to pick him up, kind of a mid-way point. My mother is very experienced with hedgehogs, and I felt comfortable with the care he would be receiving. Anyways, for this trip, I decided to purchase a small pack of aspen shavings, thinking because he wouldn't have access to his potty box, it would be easier to just put him on the shavings for a bit and just throw the shavings out when we arrived there. It was the same brand that a friend of mine had used for her hedgehog, who lived to be seven years old-- it seemed to be the safest bet. When I put him in the carrier, he was fine. Three hours later, when I got him out, he was COVERED in sores. His poor little hiney was so swollen and uncomfortable! Everywhere he had had contact with the aspen shavings, he had broken out in violent hives-- including his nose. He was having difficulty breathing through the swelling. We immediately bathed him to get the oils off and called my exotics vet (I worked for him in the past, so he always takes my calls). He told us to give him a couple drops of children's benadryl and bring him in. Luckily, he is doing much better, although his little face is taking a while to heal up (his hiney's all better though!), but I can't even express the guilt I felt! When I got back to my house, I scoured the packaging for reasons why this may have happened-- on the front, it said "100% aspen shavings, hypo-allergenic"... but that couldn't be right. Then I read all the fine print... and found, on the bottom, under a flap in the plastic seam (I had to rip the package in the corner to read it) that it said, "This product may have been processed on equipment that processes cedar, pine, and other varieties of wood." SERIOUSLY??? AND THEY NEGLECTED TO MENTION THAT UNDER THE "hypo-allergenic!" CLAIM?? I was piping mad. I have since returned that bag to PetCo and ripped the manager of the store a new one (I know it's not his fault, but I was FUMING). I showed them pictures of my poor little buddy and demanded that I be directed to the person who could discuss covering his vet bills with me (you can't claim hypo-allergenic on a package that does not contain a hypo-allergenic product). We're in the midst of figuring this thing out now, but just as a warning... if you're still using aspen shavings, switch to fleece NOW, you never know when the company you're buying from is telling the truth or changing something up, and it's better safe than sorry. If I had changed his cage to this stuff and then left him to go to bed for the night, I think we would have had a MUCH different ending-- a much sadder one. Read ALL of the fine print on ANYTHING you expose your hedgie to, and keep a very close eye on your hedgie every time you introduce something new-- even just opening a new bag of the same brand of food or bedding that you've used in the past. A little extra attention to those details could save your hedgehog's life."
http://hedgehogcentral.com/forums/vi...hp?f=5&t=15125

I'm currently finding out what brand of aspen she had bought but still think it's just as important to check your brand as well.