Kidney Stones and Flank Pain

 

Kidney Stones and Flank Pain Evaluation in Princeton & Lawrenceville, NJ

Kidney stones are hard mineral deposits that form in the urinary tract. They may sit quietly in the kidney, or they may cause sudden severe pain when they move into the ureter, the tube that drains urine from the kidney to the bladder.

Patients often describe sharp pain in the side, back, flank, lower abdomen, or groin. Pain may come in waves. It may be associated with nausea, vomiting, blood in the urine, urinary urgency, burning with urination, or difficulty getting comfortable.

Flank pain is not always a kidney stone. It can also come from a urinary tract infection, kidney infection, muscle strain, low back pain, abdominal conditions, or other medical problems. Fever, chills, vomiting, dehydration, inability to urinate, or severe uncontrolled pain can make the situation more urgent.

For patients in Princeton, Lawrenceville, West Windsor, Plainsboro, Hopewell, Pennington, Robbinsville, and nearby Mercer County communities, the goal is to identify whether symptoms are likely from a stone, infection, back problem, or another cause, then decide what testing, treatment, imaging, or referral is needed.

This page is educational. It can help you understand symptoms, diagnosis, treatment options, prevention, and when to seek urgent care.

QUICK TAKEAWAYS

• Kidney stones can cause severe pain in the flank, side, back, lower abdomen, or groin.
• Pain may come in waves and may be associated with nausea, vomiting, urinary urgency, burning, or blood in the urine.
• Fever, chills, vomiting, dehydration, inability to urinate, or severe uncontrolled pain should be evaluated urgently.
• A kidney stone with infection or urinary blockage can become serious.
• Diagnosis may involve urine testing, blood work, and imaging such as ultrasound or CT depending on symptoms and risk.
• Many small stones pass on their own, but larger stones, infected stones, blocked stones, or stones causing severe symptoms may need urgent care or urology treatment.
• If flank pain, urinary symptoms, or possible kidney stone symptoms are concerning, schedule an evaluation with Princeton Sports and Family Medicine, P.C. or start here: Request Appointment.

WHO THIS AFFECTS + WHY IT HAPPENS

Who gets kidney stones?

Kidney stones can affect adults of any age. Some people have one stone episode. Others have recurrent stones.

Risk may be higher in people with:

• Prior kidney stone history
• Family history of kidney stones
• Dehydration or low fluid intake
• Hot-weather work or exercise with heavy sweating
• High sodium intake
• Certain dietary patterns
• Recurrent urinary tract infections
• Gout or high uric acid history
• Certain bowel conditions or surgeries
• Certain medications or supplements
• Obesity or metabolic risk factors
• Diabetes or insulin resistance
• Certain kidney or urinary tract conditions

Athletes, outdoor workers, and active adults can be at higher risk during periods of heat, heavy sweating, travel, or inadequate hydration.

Why kidney stones happen

Kidney stones form when minerals and salts in the urine become concentrated enough to crystallize. Different stones can form for different reasons.

Contributors may include:

• Not making enough urine each day
• Dehydration
• High urine calcium, oxalate, uric acid, or other minerals
• Low urine citrate in some patients
• High sodium intake
• Recurrent infection
• Genetic or metabolic factors
• Certain medical conditions
• Certain medications or supplements

The prevention plan depends on the type of stone and why it formed. That is why stone analysis and follow-up testing may matter for recurrent stones.

SYMPTOMS + WHAT’S NORMAL VS NOT

Common kidney stone symptoms

Kidney stones may cause:

• Sudden sharp pain in the side or flank
• Pain in the back below the ribs
• Pain that travels toward the lower abdomen or groin
• Pain that comes in waves
• Nausea
• Vomiting
• Blood in the urine
• Pink, red, brown, or tea-colored urine
• Burning with urination
• Urinary urgency
• Frequent urination
• Passing only small amounts of urine
• Cloudy or bad-smelling urine
• Restlessness or inability to get comfortable

Pain can be severe even when the stone is small. Pain severity does not always match stone size.

Symptoms that may suggest infection or obstruction

More concerning symptoms include:

• Fever
• Chills
• Severe vomiting
• Signs of dehydration
• Inability to urinate
• Severe weakness
• Confusion, especially in older adults
• Pain that cannot be controlled
• Known kidney disease with stone symptoms
• Stone symptoms in pregnancy
• Stone symptoms in a patient with one kidney

A stone plus infection or blockage can become dangerous and may need emergency care.

What can be monitored briefly

Mild flank discomfort without fever, vomiting, urinary symptoms, blood in the urine, or worsening pain can sometimes be monitored briefly if symptoms are improving and the patient feels well.

Early steps may include:

• Hydration if you can drink normally
• Avoiding intense exercise during acute symptoms
• Tracking urinary symptoms
• Monitoring temperature
• Watching for blood in the urine
• Avoiding repeated heavy lifting if symptoms may be muscular
• Scheduling evaluation if symptoms persist, worsen, or become more classic for stone or infection

Schedule a visit if…

A scheduled evaluation is appropriate if:

• Flank pain lasts more than a day or two
• Pain comes in waves
• Pain travels toward the groin
• Blood is seen in the urine
• Urinary burning, urgency, or frequency is present
• Nausea occurs with flank pain
• You have a history of kidney stones
• You are unsure whether symptoms are kidney stone, UTI, back pain, or abdominal pain
• You need urine testing, imaging guidance, pain-control guidance, or prevention planning
• You have recurrent stones and need a prevention plan

Seek urgent care now if…

Seek urgent or emergency evaluation if you have:

• Fever or chills with flank pain
• Severe pain that is not controlled
• Persistent vomiting
• Signs of dehydration
• Inability to urinate
• Confusion or severe weakness
• Severe abdominal pain
• Blood in the urine with severe pain
• Stone symptoms with pregnancy
• Stone symptoms with one kidney
• Known kidney disease with worsening symptoms
• Pain with fainting, chest pain, or shortness of breath
• Rapidly worsening symptoms

These symptoms may require urgent imaging, IV fluids, pain control, antibiotics, or urology care.

DIAGNOSIS

Kidney stone evaluation depends on symptom severity, risk factors, exam findings, and whether infection or obstruction is suspected.

What history matters?

Your clinician may ask:

• Where the pain started
• Whether pain travels to the groin
• Whether pain comes in waves
• Whether urine color changed
• Whether burning, urgency, or frequency is present
• Whether fever or chills are present
• Whether nausea or vomiting is present
• Whether you can keep fluids down
• Whether you have had kidney stones before
• Whether you have one kidney or kidney disease
• Whether you are pregnant or could be pregnant
• What medications or supplements you take
• Whether you have gout, bowel disease, or recurrent UTIs
• What you have already tried for pain or hydration

What the exam may include

A typical evaluation may include:

• Temperature
• Heart rate
• Blood pressure
• Hydration assessment
• Abdominal exam
• Flank or costovertebral angle tenderness
• Low back and muscle exam when relevant
• Assessment for signs of infection
• Assessment for severe abdominal causes
• Review of medications and kidney-risk factors

The exam helps separate kidney stone symptoms from UTI, kidney infection, low back pain, muscle strain, abdominal pain, appendicitis, diverticulitis, gallbladder disease, ovarian/testicular conditions, and other causes.

Urine testing

Urine testing may include:

• Urinalysis
• Microscopic blood check
• Infection markers
• Urine culture when infection is possible
• Pregnancy testing when appropriate

Blood in the urine can support the diagnosis, but not every stone patient has visible blood.

Blood work

Blood work may be considered when:

• Infection is possible
• Kidney function needs to be checked
• Vomiting or dehydration is present
• Pain is severe
• Symptoms are persistent
• The patient has kidney disease, diabetes, or other risk factors
• Medication safety needs to be assessed

Imaging

Imaging may be considered when:

• Stone is suspected
• Pain is severe
• Diagnosis is unclear
• Fever or infection is possible
• Symptoms persist
• The patient has one kidney or kidney disease
• Vomiting or dehydration is present
• There is concern for obstruction
• A first stone episode needs confirmation
• Symptoms do not follow a typical pattern

Possible imaging may include:

• Ultrasound
• CT scan
• X-ray in selected situations

CT is often very helpful for identifying stones, but the right imaging choice depends on the patient, radiation considerations, pregnancy status, severity, and clinical setting.

TREATMENT OPTIONS

Treatment depends on stone size, stone location, pain severity, infection risk, kidney function, hydration status, and whether urine flow is blocked.

Pain control

Pain control is often the first priority.

Options may include:

• Anti-inflammatory medication when safe
• Acetaminophen when appropriate
• Prescription pain medication in selected cases
• Nausea medication when needed
• Emergency care for IV medication if pain is severe

Medication choices should be individualized based on kidney function, blood pressure, stomach history, bleeding risk, heart history, medication list, and other medical factors. NSAIDs are not safe for every patient.

Hydration

Hydration matters, but forcing large amounts of fluid during severe pain or vomiting may not help and can worsen discomfort.

General guidance:

• Drink fluids if you can tolerate them
• Avoid dehydration
• Seek care if you cannot keep fluids down
• Use prevention-level hydration once the acute episode is controlled

Medical expulsive therapy

In selected patients, a medication may be prescribed to help relax the ureter and support stone passage. This depends on stone size, location, patient history, and clinician judgment.

This is not appropriate for every stone.

Straining urine

Some patients may be asked to strain their urine to catch the stone. If a stone is captured, it can sometimes be sent for analysis. Knowing the stone type can help guide prevention.

Antibiotics

Antibiotics may be needed if infection is present or strongly suspected.

Antibiotics are not used simply because a stone exists. They are used when bacterial infection is part of the picture.

A stone with infection can be serious and may need urgent or emergency care.

Urology referral

Urology referral may be appropriate when:

• Stone is large
• Stone is not passing
• Pain remains severe
• Vomiting or dehydration persists
• Kidney function is affected
• Infection or obstruction is suspected
• Stones keep recurring
• Imaging shows a concerning stone location
• A procedure may be needed

Procedures

Some stones require procedures to break up or remove the stone. Options may include shock wave lithotripsy, ureteroscopy, stent placement, or other urologic procedures depending on stone size, location, and urgency.

These decisions are typically made with a urologist.

Emergency care

Emergency care may be needed for:

• Infected obstructing stone
• Severe uncontrolled pain
• Persistent vomiting
• Dehydration
• Kidney dysfunction
• Inability to urinate
• Severe illness or sepsis concern

The goal is to prevent complications and protect kidney function.

RETURN TO WORK, SCHOOL, SPORT, AND ACTIVITY GUIDANCE

Return to activity depends on pain control, hydration, fever, infection risk, medications, and whether the stone has passed.

During acute stone symptoms

Usually avoid:

• Intense exercise
• Heavy lifting
• Long runs or hard workouts
• Heat exposure
• Alcohol
• Dehydrating conditions
• Training through severe pain
• Driving if taking sedating pain or nausea medication

Often appropriate:

• Rest
• Gentle walking if tolerated
• Hydration as tolerated
• Medication as prescribed
• Monitoring urine output
• Following imaging and follow-up guidance

After symptoms improve

Gradual return may be appropriate when:

• Pain is controlled
• No fever or chills are present
• Nausea and vomiting have resolved
• Hydration is normal
• Urination is normal
• Medications do not impair alertness
• Clinician guidance has been followed

If infection or kidney involvement occurred

Avoid intense exercise until:

• Fever is gone
• Antibiotics are working if prescribed
• Hydration is normal
• Strength and energy are returning
• A clinician has cleared return if symptoms were severe

Athletes and active adults

Athletes should be cautious with:

• Heat training
• Long endurance sessions
• Heavy sweating
• Travel tournaments
• Weight cuts
• High-protein supplement changes
• Dehydration-prone training blocks

Return should include a hydration and prevention discussion if stones are recurrent or if training conditions raise risk.

Common mistakes

• Ignoring fever with flank pain
• Trying to “flush out” a stone while vomiting
• Training hard during severe pain
• Delaying care when unable to urinate
• Using leftover antibiotics
• Assuming all flank pain is back strain
• Assuming all back pain is a kidney stone
• Not following up after recurrent stones
• Not analyzing or saving a passed stone when recommended
• Not adjusting hydration during heat or heavy training

PREVENTION

Prevention depends on stone type and risk factors. A prevention plan is most helpful after the stone type is known.

Helpful steps may include:

• Drinking enough fluid to keep urine pale
• Increasing fluids during heat, sweating, travel, or long training sessions
• Reducing high sodium intake
• Avoiding dehydration
• Reviewing supplements with a clinician
• Avoiding extreme diet changes without guidance
• Maintaining normal dietary calcium unless told otherwise
• Adjusting oxalate intake if advised
• Moderating excessive animal protein if advised
• Using citrus or citrate strategies when appropriate
• Managing gout, diabetes, or metabolic risk factors
• Completing a 24-hour urine evaluation in selected recurrent cases
• Following up with urology or primary care after recurrent stones

A common mistake is cutting out all calcium. For many stone-formers, normal dietary calcium is important. Prevention should be individualized.

HOW PSFM CAN HELP

At Princeton Sports and Family Medicine, P.C., we evaluate flank pain, urinary symptoms, blood in the urine, nausea, vomiting, fever, and possible kidney stone symptoms by first assessing severity and safety.

A visit may include a focused history, abdominal and flank exam, urine testing, medication review, hydration assessment, and discussion of whether blood work, imaging, emergency evaluation, or urology referral is needed.

For patients with suspected uncomplicated stones, care may include pain-control guidance, hydration guidance, urine straining, medication review, and follow-up planning. For patients with fever, chills, severe pain, vomiting, dehydration, kidney-risk factors, or concern for obstruction, urgent or emergency evaluation may be recommended.

For patients with recurrent stones, we can help coordinate prevention planning, review diet and hydration patterns, and determine whether urology evaluation, stone analysis, blood work, or 24-hour urine testing should be considered.

Depending on the situation, care may involve Primary Care Services.

Schedule an evaluation with Princeton Sports and Family Medicine, P.C. in Lawrenceville, NJ, or start here: Request Appointment.

FAQs

What does a kidney stone feel like?

A kidney stone may cause sharp pain in the side, flank, back, lower abdomen, or groin. The pain may come in waves and may be associated with nausea, vomiting, urinary urgency, burning, or blood in the urine.

Can kidney stones cause blood in the urine?

Yes. Kidney stones can cause pink, red, brown, or tea-colored urine. Blood may also be microscopic and only seen on urine testing.

Can kidney stones cause nausea and vomiting?

Yes. Kidney stone pain can trigger nausea and vomiting. Persistent vomiting or dehydration should be evaluated urgently.

When is a kidney stone an emergency?

Seek urgent care for fever, chills, severe uncontrolled pain, persistent vomiting, dehydration, inability to urinate, confusion, pregnancy, one kidney, known kidney disease, or rapidly worsening symptoms.

Is flank pain always a kidney stone?

No. Flank pain can also come from muscle strain, low back pain, urinary tract infection, kidney infection, abdominal conditions, or other medical problems.

Do I need imaging?

Not always, but imaging may be needed when symptoms are severe, diagnosis is unclear, infection or obstruction is possible, pain persists, or this is a first or complicated stone episode.

Can small kidney stones pass on their own?

Yes. Many small stones pass without a procedure. However, the plan depends on stone size, location, pain, infection risk, and kidney function.

Should I drink a lot of water during a stone attack?

Drink fluids if you can tolerate them, but do not force large amounts if you are vomiting or in severe pain. Seek care if you cannot keep fluids down.

How can I prevent another kidney stone?

Prevention depends on stone type. Common steps include staying well hydrated, reducing excess sodium, avoiding dehydration during heat or exercise, reviewing supplements, and considering stone analysis or 24-hour urine testing for recurrent stones.

Do you evaluate kidney stones near Princeton and Lawrenceville?

Yes. Princeton Sports and Family Medicine, P.C. evaluates flank pain, urinary symptoms, and kidney stone concerns for patients from Princeton, Lawrenceville, West Windsor, Plainsboro, Hopewell, Pennington, Robbinsville, and nearby Mercer County communities.

RELATED CONDITIONS

Patients with kidney stone symptoms, flank pain, or urinary symptoms may also want to learn about:

• UTI
• Abdominal Pain
• Nausea and Vomiting
• Fever
• Low Back Pain
• Acute vs Chronic Pain
• When to See a Clinician

Because flank pain, urinary symptoms, nausea, fever, abdominal pain, and low back pain can overlap, a focused evaluation can help identify whether symptoms are more likely from a kidney stone, UTI, kidney infection, back strain, or another cause.

RELATED PSFM SERVICES

• Primary Care Services

Kidney stone pain can be intense, but not every flank pain episode is a stone. A stone with fever, chills, vomiting, dehydration, inability to urinate, or infection concern can become urgent.

You do not need to guess whether symptoms are kidney stone, UTI, kidney infection, low back pain, abdominal pain, or another cause. A focused evaluation can help clarify the next step and determine whether urine testing, imaging, medication, urology referral, or emergency care is needed.

Schedule an evaluation with Princeton Sports and Family Medicine, P.C. in Lawrenceville, NJ, or start here: Request Appointment.

MEDICAL DISCLAIMER

This page is for general education and does not replace medical advice. Symptoms can have more than one cause. If you have severe symptoms, rapidly worsening pain, chest pain, shortness of breath, one-sided weakness, uncontrolled bleeding, signs of serious infection, inability to urinate, severe vomiting, fever with flank pain, or any urgent concern, seek immediate medical evaluation.