Posted most of this previously. There is an update at the end.

In 1992, at age 51, I had a large melanoma removed from my back. At that time I was getting a lot of seborrheic keratoses, and some actinic keratoses, and had a kind of rash of small red spots on my chest. I saw another dermatologist who biopsied the red spots which turned out to be Grover's Disease. Other then annual full body exams for a possible recurring meloma and a few basal cell carcinomas removed, I didn't have any more problems until January 2007. The Grover's was always there but didn't seem to bother me.

At the end of 2006, I retired and moved from a foggy climate to a more dry climate. By January 2007, I started having terrible itching on my chest and back. A new dermatologist again biopsied the red spots and they were still Grover's. He prescribed ointments, including a pretty expensive one (Dovenex), but none of them helped very much. The only thing that sort of worked, out of many tried, was Eucerin Itch Relief. Most of the time I was reading and posting on a website called Skincell. There were many people with many wild (IMO) theories as to what causes Grover's. Some attributed it to the mercury in their dental fillings and were having all their fillings removed and redone. In addition to the itching, the red spots often got a little crusty and would sting if I got sweaty.

I finally got an appointment with Dr. Jack Resneck at UCSF in June 2008. He prescribed Gabapentin (Neurontin), 300 mg every night and the itch went away. It was gone until about June 2021 when it started coming back slowly. I don't know if the Gabapentin really worked or the disease just went away for 13 years.

UCSF was across two bridges and about 35 miles away so I had found a dermatologist closer to home for my annual exams. As the itch bacame as bad as it's ever been, I've tried to get the new dermatologist and my PCP to prescribe something to help. The derm prescribed Triamcinolone Acetonide Cream, which can cause or worsen glaucoma. As my wife has some serious glaucoma, I couldn't risk it. I used the Eucerin Itch Relief for a few months then my PCP prescribed Hydroxyzine which gives me some relief as it makes me go to sleep. When it wears off after about six to seven hours, the itching comes back. To honest, I'm not sure if the widespread ketatoses don't also itch.
Apparently, the website Skincell is no longer what it used to be and this site is one where I can find other people discussing Grovers. I was hoping there had been some kind of breakthrough in the last 15 years. Apparently not. I'm now also on the Facebook Grover's page.
I'm curious about the Cilantro and Chlorella smoothie approace but I'm one of those people to whom Cilantro tastes like soap.
9/1/23 Update: I've been taking Cilantro and Chlorella capsules for 4 months today. No help. I've also been using Eucerin Calming Body Wash for about 5 months which seems to help on a sporadic basis. Still using Eucerin Itch Relief when it gets real bad which helps for sever hours and taking the Hydroxyzine.
Assuming the 13 years with no itch was due to the Gabapentin and not the "transient" part of this disease, I would have to recommend trying the Gabapentin to anyone new to this misery. Just remember, nothing seems to work for everybody.