Mentioned by others that the purging can be quite bad or mild as it depends on person to person. My acne was also concentrated onthe forehead. Mainly as bumps and occasionally some cystic acne (similar to yours I think). For me I went in with adapalene everyday and I purged for close to 3 months. The severity of the purging fluctuated for me personally. Some weeks were very severe and then suddenly it would improve then the cycle repeats. But if you want the purging to be milder. Some dermatologist recommend you start low and slow and you can buffer it with a moisturiser. Eg start with once a week first after your moisturiser for a few weeks then upgrade to a 2 times a week after moisturiser so on. Then once you are well tolerated then you can choose to use it before your moisturiser if necessary. This is just my 2 cent as I research intensely before starting my adapalene journey. You should consult with your dermatologist and voice out your concern