I suggest a test patch given the extent. This means treating a smaller area to see how you respond. Options are listed below.
Old stretch marks are harder to treat- my preferred option for old, white, silvery- papery stretch marks is a combination of CO2 fractional laser, or with INFINI RF and PRP. I also use Fraxel ReStore 1550, and also lasers in the 1540 wavelength. Of all the methods I find microneedling with RF energy and PRP the best, as it has the lowest rate of skin colour changes, and the fastest healing time. Results wise, it outperforms CO2 laser!
The truth is that stretch mark treatments are HIGHLY variable, depending on your own immune system, your skin type and the age of the stretch marks. Some get a 30% improvement, others up to 80%. An assessment is the very first step
Dr Davin Lim, Laser and aesthetic dermatologist.