I started taking these 6 weeks ago. I immediately began breaking out in cystic acne on my chin and upper lip area. I first attributed the breakouts to stress, and two weeks later I thought it had to be my cycle. When I was still breaking out two weeks after that, I began to get desperate and started buying stronger acne cleansers, but nothing was helping.. Finally, it came to me that the acne started at the same time I added these vitamins to my regimen. Within 3 days of stopping, I quit getting new blemishes, within 5 days my skin has completely cleared up. If the internet is to be believed, the culprit is likely biotin. I will be trying another prenatal without that ingredient and see what happens