Lifestyle

Sudden Pain in the Side or Back That Comes in Waves Can Signal a Kidney Stone. Signs That Need Care Right Away

By Curtis Jones · October 28, 2026

The pain often arrives without warning. It can start in the side or back, ease off for a while and then return just as hard. For many people, that pattern is the first sign of a kidney stone.

A kidney stone is a hard object that is made from chemicals in the urine, according to the National Kidney Foundation. When there is too much of some chemicals and not enough water, they can stick together and form a stone. The foundation says about 1 in 10 people will get a kidney stone at some point in their life, and men are slightly more likely to get them than women.

MedlinePlus, the National Library of Medicine’s consumer health site, says symptoms may not appear until the stone moves down the ureter, the tube that carries urine to the bladder. There, the stone can block the flow of urine and cause pain.

These are the signs listed by the National Institute of Diabetes and Digestive and Kidney Diseases, MedlinePlus and the National Kidney Foundation.

Sharp pain in the back, side, belly or groin. The NIDDK lists sharp pains in your back, side, lower abdomen, or groin. MedlinePlus describes severe pain that starts and stops suddenly, felt in the belly or the side of the back, which may move to the groin.

Pain that comes and goes in waves. The NIDDK says the pain may last for a short or long time or may come and go in waves.

A vague ache that will not go away. The kidney foundation says some people have a pain or stomachache that is harder to describe and doesn’t go away.

Blood in the urine. The NIDDK says urine may look pink, red or brown.

Cloudy or bad-smelling urine. Both the NIDDK and the kidney foundation list it.

Changes in urination. The NIDDK lists pain while urinating, a constant need to urinate, and being unable to urinate or able to pass only a small amount. MedlinePlus lists a burning feeling when urinating.

Nausea and vomiting. All three sources list them.

Fever and chills. All three also list fever and chills. MedlinePlus says surgery is often needed when a stone is blocking urine flow and causing an infection, or when there is a urinary tract infection or fever.

The NIDDK advises seeing a health care professional right away for any of these symptoms, since they may point to a kidney stone or a more serious condition. MedlinePlus singles out severe pain in the back or side that will not go away.

Treatment depends on the stone’s size, location and type. The NIDDK says small stones may pass on their own, sometimes with plenty of liquids and pain medicine. Larger stones, or stones that block the urinary tract or cause great pain, may need urgent treatment. The kidney foundation says passing a stone can take hours to weeks. MedlinePlus adds that being pain free does not confirm that a stone has passed.

Some health conditions make stones more likely. The kidney foundation lists diabetes, weight loss surgery, inflammatory bowel disease, an overactive parathyroid gland, gout and repeat urinary tract infections. It also says diets high in sodium, added sugar and meat, with too little water, fruits, vegetables and calcium, can cause stones in people who are prone to them.

Stones also tend to come back. The NIDDK says drinking enough liquids each day is in most cases the best way to help prevent most types, and that people without kidney failure should drink six to eight 8-ounce glasses a day.

This article is for general information and is not medical advice. Talk with your doctor about any symptoms, and seek care right away for severe pain, fever or vomiting. This article was produced with the assistance of AI and fact-checked against the sources cited by LightWave Reports.