No idea. We have all sorts of people here. Don't live in fear. Many have auto immune issues, or other health concerns. Some don't heal properly. If Retin A works well for you then continue to use it. Just stop while you treat or are healing. .5% has been effective for many people and you can use moisturizer to make it weaker if you wish (mix). Retin A can make some peoples scars worse as they have issues they were not aware of (it accelerates the skin turn over). Like a peel can uncover scars that had dead skin over them. If it doesn't work for you stop. Many Many people use this often.

Retin A (and AHA or every chemical substance that "peel" the skin) can break down the skin tissue and make the scars worse if you have no ability to heal.
It has shown benefits to a lot of people tho.You just need to know if you are a poor healer or have some immune systeme issues las BA said.