Do TENS units actually work for back pain?

Across r/backpain, r/ChronicPain, and r/ehlersdanlos threads we read, the consensus is that TENS reliably interrupts pain signals during use and for a short window afterward — several users described drops from a 9/10 to 5-6/10 — but it is not a long-term fix. It tends to work best for muscle spasms and acute flares; nerve pain often requires longer sessions before relief sets in.