Kidney Stone
Watch the Fever, Not Just the Pain
General information from an emergency physician. It adds to your discharge papers and does not replace them or your own doctor. What this site is and isn’t
Key Takeaways:
- Stone pain comes from backed-up pressure, not the stone cutting tissue.
- Forced fluids do not push a stone out faster.
- Fever with a blocked stone is an emergency.
About Your Diagnosis & ED Workup
When a stone blocks urine flow, pressure builds behind it and stretches the kidney area. The ureter squeezes in waves, which causes waves of pain over a steady background ache.
Pain may move from the side toward the groin as the stone moves down. That shift often means progress, not new damage.
A CT that shows a stone does not by itself exclude infection or every blood-vessel, bowel, or pelvic cause of pain.
First Steps & Evidence-Based Home Care
Use the pain plan from discharge. Anti-inflammatory drugs often treat stone pain better than opioids, but they can harm kidneys or cause bleeding in some people.
Drink enough to avoid dehydration. Do not force gallons of water or seek extra IV fluid to flush the stone; forced hydration does not improve pain or passage.
If you capture or pass the stone, ask whether it should be tested. Stone composition can guide prevention.
Timeline & Expected Recovery Course
Two-thirds of stones that pass do so within four weeks. Stones still present after one to two months are unlikely to pass with more waiting.
Size and location matter. Nearly 89% of stones under 5 mm passed in one large study, compared with 29% of stones over 7 mm.
Kidney stones often return. Without prevention, 35% to 50% recur within five years.
Emergency Red Flags (When to Return Immediately)
Return to the emergency department for any of these. This list is not exhaustive.
- A fever of 38 °C / 100.4 °F or higher, chills, or shaking chills. A blocked stone with infection can lead to sepsis and death.
- Pain that the prescribed oral plan does not control, because a stone may need urgent treatment.
- Vomiting that keeps you from taking medicine or fluids, because home treatment is no longer working.
- Much less urine or no urine, because blockage can harm kidney function.
- Worsening side pain with a fast heart rate, lightheadedness, confusion, or a severely ill feeling. These can be signs of infection affecting the whole body.
Reviewed September 3, 2026