If you have been in pain for months, or years, you have probably had the same frustrating experience: something helps for a while, then stops. The physio gets you to 70% and plateaus. The ibuprofen works until it does not. The heat patches give you twenty minutes. You go back to square one.
This is not weakness, and it is not bad luck. It is how chronic pain works neurologically. After sustained pain, the nervous system itself changes — the pain-sensing pathways become more sensitive, firing more easily and with less provocation. Researchers call it central sensitisation. The original cause of the pain may have healed. The signal loop has not.
This is why most treatments fail in the long run: they address the structure, the inflammation, the symptom. TENS is one of the few approaches that directly targets the pain signal pathway itself.
It does not work for everyone. That is the honest answer. But if you have tried everything else, the question worth asking is whether you have ever targeted the right thing.