Does anyone have any experience with TENS?

I was prescribed a TENS for muscle spasms in my back right below my shoulder blades. The TENS was the only thing that helped. I did wear the unit constantly for a while.

So sorry about your Shingles. They are horrible. The nerve pain can be excruciating and can remain after the rash clears. Hoping you find relief soon!

I had TENS with PT for a frozen shoulder,, I loved it and it made all the other stuff worthwhile. Enjoy and use as needed

Undergoing tens with ultrasound at physical therapy now, for the past several weeks.
When the PT doctor places the leads, I get more relief, than if, say, for example, a tech places the leads. But they are good techs.
One tech misplaced a lead over a nerve, leading to increased pain, so I wasn't liking it at first.
It does help.
Aleve now sells a home unit, battery operated. Going to try it again.

There are medications for nerve pain....Lyrica (pregabalin?) and Neurontin (gabapentin)
comes to mind, but I could be wrong.
Maybe ice could also help the pain of shingles?

I own a TENS machine that is portable and battery operated. I have had a lot of success in the past for my back, but it irritates my shoulder and neck when I have used it there.

I use my TENS unit only when I have pain...neuropathy or muscle pain. I didn't own it when I had shingles. Four years sounds extremely long. My shingles was severely painful but lasted maybe 3 months and maybe only 1 month was very bad. The TENS unit helps but doesn't necessarily get rid of all the pain, just as GardenArtist noted. I hope you are better very soon.

I've used it on several occasions when I've had therapy for knee injuries. It was absolutely wonderful! The deeper stimulation relieved pain so effectively. At one point I considered getting one for myself, and probably should have.

I've also had ultrasound and of course PT, but for me PT with TENS and U/S is the best combination.

Using it for shingles isn't a use with which I'm familiar and that's a different kind and source of pain.

For me it wasn't a question of being able to use it continuously as the equipment was only available when I had PT.

I'm wondering though why your shingles pain is "ongoing". Have you actually had it for 4 years? That's really a long time for Shingles, which I understood generally wasn't ongoing for that long a period. That must be debilitating.