“How long is pain after hip replacement?”

No answer for that as everyone is different. Typically pain gets gradually better over the following weeks.

Hip pain comes from muscle/fascia strain outside and around the joint and not from the joint itself. Surgery is only indicated when the joint is damaged enough, no longer working as a hinge or bearing weight.  After joint replacement, the source of pain remains untreated and will last for a lifetime until treated. Now there is an added surgical injury, which will also remain a lifetime until treated. Both kinds of injury are not to be treated with physical therapy for stretching/strengthening which will worsen the injuries. Therefore those injuries along with pain are likely to remain for a lifetime. Such soft tissue injury can only be effectively treated internally by self-healing via light touch, and not by any external means, e.g., medication, massage, manipulation, hot/cold application, electrotherapy, and certainly not stretching or strengthening exercises!

Usually down to simply meds like Tylenol or ibuprofen in 1 to 2 weeks.