There are different triggers for different people. Sometimes it comes and goes all by itself. That's the "transient" part. I've had the rash since 1992 (confirmed by biopsy) but it didn't itch until 2007 and it went on for 18 months until a derm prescribed Gabapentin (300 mg every night) and it went away immediately and stayed away for 13 years although I still had some rash. It came back in 2021 and I still have the itch. I had about 12 weeks of NB UVB (blue) last summer and I think it helped a little. I use Eucerin Itch Relief after every shower and take Hydroxyzine every night to get some sleep. I recommend also signing up for the Facebook forum for Grover's.