Kidney Pain: What Causes It and Where It Is Felt

A nagging pain in the kidney area does not always mean kidney disease: the lower back can hurt in a similar way. Below — where kidney pain is felt, what causes it, and which signs mean you need to see a doctor urgently.

Where the kidneys are and where it hurts when something is wrong with them

There are two kidneys. Each is about the size of a fist, and both lie closer to the middle of the back, just under the ribs. Inside each are about a million tiny structures, nephrons: they filter the blood, remove waste and excess water, and the resulting urine travels down the ureters to the bladder.

That is why kidney pain is felt in the side or back, in the area under the lower ribs. With renal colic, a stone injures the surface of the ureter and blocks the outflow of urine, and the pain radiates to the iliac and inguinal areas, above the pubis, to the inner surface of the thighs and the external genitalia.

Can the kidneys hurt on their own

Yes. With colic, pressure in the renal pelvis rises because urine is retained, blood circulation in the kidney is impaired — and the pain becomes sharp. The attack begins suddenly, when everything was fine before, day or night, at rest or in motion, and lasts from a few minutes to a day or longer; if a stone is stuck — up to a week. After the attack, a dull pain remains in the lumbar region, but the person feels noticeably better.

What causes kidney pain: the main causes

• Infection. A kidney infection is a painful urinary tract infection that can affect one or both kidneys. Without treatment it is dangerous, up to and including sepsis.
• Stone. Renal colic is the most common syndrome in the clinical picture of urinary tract diseases, and it is most often caused by urolithiasis.
• Injury. A kidney contusion and other injuries are named by doctors among the causes of kidney damage.
• Other diseases. Cysts, stones, infections, tumors, hereditary problems and the effects of certain medications.

A kidney infection often starts as cystitis, but it can occur without it. The risk is higher if there is already a kidney problem, such as stones, in certain conditions and with a weakened immune system. Such infections are more common in women, although anyone can get them.

There are figures about stones. With a kidney stone, colic occurs in 50% of patients; with a ureteral stone — in 95–98%. Up to 70% of patients with colic are men, because of the narrowness of the ureter. Chronic kidney disease damages nephrons slowly, over several years; the doctor checks the kidneys with blood and urine tests.

Left and right kidney: is there a difference in pain

A kidney infection can affect one kidney or both. With colic, the pain travels along the ureter: to the groin, above the pubis, to the thigh. When it descends toward the pelvis, it usually weakens, and before the stone passes there is brief pain and a stinging sensation.

Kidneys or lower back: how to tell the pain apart

The lower back is muscles, ligaments and the spine, and pain there is not always related to the kidneys. Kidney pain is revealed by accompanying signs: fever, nausea and vomiting, muscle aches and flu-like symptoms, pain or burning during urination, urges that are more frequent and sharper than usual, dark or cloudy urine. With colic, the pain is so severe that the person paces and looks for a position that makes it easier, and the urine turns red or dirty black because of blood and sand.

Warning signs and when to see a doctor

See a doctor if pain or burning during urination, frequent and sharp urges, dark or cloudy urine persist, and also if the symptoms of a kidney infection have not gone away after treatment. An urgent consultation is needed if a kidney infection is suspected and there is a very high fever or chills, a temperature below 36 °C, pain in the lower abdomen or in the back just under the ribs, blood in the urine, nausea and vomiting, if no urine has been passed in a day, and during pregnancy.

Kidney pain on its own is not a reason to call an ambulance. 103/112 — if, when a kidney infection is suspected, the person is disoriented, drowsy or has difficulty speaking: this is life-threatening.

And lastly: this text is for reference. It does not replace a doctor's consultation and does not answer the question of what exactly is hurting in your case.

This content is for reference and does not replace a doctor's consultation. Medical disclaimer