How long after using the Retin-a should I start to notice a difference? Do I use it continuously even if I don't break out?

It's great to hear that you're seeing your natural skin tone returning after your break from tretinoin. Here are some important considerations regarding sun exposure and tanning: Sun Sensitivity: Tretinoin can increase your skin's sensitivity to the sun, which might have contributed to the...

Tretinoin generally comes in 0.025%, 0.05% and 0.1%. Retin-A comes in 0.04% and 0.1%. As these are prescribed medications, your dermatologist should decide which strength is best for you. In general, if you have dry, sensitive skin, start low (0.025% or 0.04%). You can always go stronger...

I am assuming you were applying the SkinCeuticals 1.0 to dry skin. This is key. It is the only product you want to put on to dry skin, NOT wet or damp skin. Also, depending on where you live, I don't recommend any form of retinol be used daily. I start with a maximum recommendation of 3x per...

All drugs slowly degrade over time.  Your Retin-A may have lost some of its potency but it is probably still active enough for you to continue using it.  I would expect that by 18 months it would be time for a refill.  

I would not expect any topical treatment to improve the color of your scar at this point.  It is possible that a scar revision may be possible.  

What in the world are Bee Venom Masks and how are these reported to be beneficial.  Retin-A on the other hand should be used at night.