Is Retin A (tretinoin) toxic? I read in some internet material that Retin A is poisonous and actually harmful for body.

I came across on online discussion while doing research about tretinoin, since I'm using it for couple months already (with side effects).In that material they where basically saying that Retin A is toxic and it is poisonous for body and all the swelling, irritation and other side effects come from our body's natural ability to fight against unwanted and toxic ingredients infused to our body.I would like to get professional opinion about the toxicity of tretinoin especially during long time use