[Product Question] What is it about niacinamide that can cause acne? I've been told to use it for scarring and PIE but since I stopped using it my skin became clearer - any way to use it and not get acne?

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I want the benefits of using niacinamide for post acne scarring and marks but after I stopped using it a few weeks ago (because I saw a lot of comment about it causing acne) my acne did reduce.What is it about niacinamide that causes acne? I was using The Ordinary's Niacinamide and Zinc solution.Is there a way to use it (maybe just using less at a time?) that doesn't cause breakouts?Thank you in advance :)Edit Could it possibly be used directly on the PIE/scars (and only those specific areas) to reduce them without smearing it all over your face? Almost like a spot treatment but for blemishes?
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Submitted by DustyLemonTree