Appendicitis vs. Kidney Stones

Telling the difference between appendicitis and kidney stones may sometimes be difficult.

Appendicitis is often an acute problem that results from an inflamed or diseased organ. Kidney stones usually develop over time when crystals form and come together in your urinary tract. Both problems can cause intense pain on the right side of your body, making it hard to know the cause of your pain.

This article discusses appendicitis versus kidney stones and how these problems differ in their causes, diagnosis, types of pain, and treatment.

ultrasound on side

stefanamer / Getty Images

Kidney Stones: Urinary System

Kidney stones are a common cause of kidney pain, also known as renal pain. Your kidneys are bean-shaped organs located just under your rib cage, on either side of your spine. They filter blood to remove waste and maintain a healthy balance of bodily fluids, resulting in the production of urine.

Your urine travels through tube-like muscles called ureters, which connect your kidneys to your bladder. When urine reaches your bladder, it remains there until you empty it by urinating. Urine exits your body through your urethra, a tube at the bottom of your bladder.

Kidney stones are hard, solid masses from the crystals of certain substances eliminated naturally in your urine. Crystals form when your urine contains too much of a waste substance in too little liquid. Stones develop as the crystals join together with other elements and form a solid mass.

If you have one kidney stone, you have a higher risk of having others simultaneously or later. One kidney stone gives you a 50% risk of developing another in five to seven years.

Kidney stones typically form from one of the following substances:

  • Calcium: About 80% of kidney stones are calcium stones. These stones can form from calcium oxalate or calcium phosphate. Calcium oxalate kidney stones are the most common type.
  • Uric acid: Uric acid stones occur when there are high uric acid levels, creating hyperuricemia in your urine. Uric acid is a waste product produced from chemical changes in the body.
  • Struvite: Also known as infection stones, struvite (magnesium ammonium phosphate) stones occur due to urinary tract infections (UTIs). Some bacteria increase urinary ammonia production and make the urine more alkaline and less acidic, which creates an environment supportive of struvite stones.
  • Cystine: Cystine stones occur in patients with cystinuria, an inherited disorder in which large amounts of the natural cystine leak into your urine. When urine contains too much cystine, stones can form.

You can pass small kidney stones (less than 5 millimeters in diameter) out of your body in your urine, often without your knowledge. However, problems can occur when the stones continue to grow and become too large for natural elimination through urine.

Pain occurs when a kidney stone causes a blockage and prevents urine from passing from the kidney to the bladder. The buildup of urine can cause a backup of urine into the kidney, causing it to stretch and swell. If the blockage occurs in the ureter, it can trigger painful spasms because this organ is very sensitive to stretching.

Risk Factors for Kidney Stones

A family history of kidney stone disease is one of the most significant risk factors for kidney stones. You may also be more likely to have kidney stones if you are between the ages of 40 and 65 and have any of the following risk factors:

Appendicitis: Digestive System

Appendicitis is a medical condition in which your appendix becomes blocked by a mass such as feces, a foreign object, or a tumor. This small, finger-shaped tube is part of the digestive system. It is joined to your large intestine in the lower right of your abdomen.

Though little is known about its function or contribution to the digestive system, recent research indicates that your appendix may serve a preventive role by storing good gut bacteria that can fight illness and bacterial imbalances.

Appendicitis is considered a medical emergency because it can quickly become serious. When your appendix becomes blocked, bacterial overgrowth forms around the obstruction, resulting in inflammation and damaged tissue. This raises the possibility of your appendix bursting. If this occurs, you are at risk of peritonitis, a life-threatening infection caused by the spread of bacteria into your abdomen.

Appendicitis is usually an acute condition. It is usually treated with an appendectomy, a surgical procedure in which the appendix is removed. For some people, the condition can be managed with antibiotics. In rare cases, symptoms can come and go, causing chronic appendicitis.

Risk Factors for Appendicitis

Appendicitis can happen to anyone at any age. Having one or more of the following risk factors can increase your odds of developing this condition:

  • Your age is between 10 and 30 years old
  • Family history of appendicitis
  • Male gender
  • Cystic fibrosis (in children)

Appendicitis vs. Kidney Stones: Pain Characteristics

The pain appendicitis and kidney stones cause can be confused with one another because the two conditions share similar symptoms. It can be easy to mistake appendix pain for kidney pain.

Understanding how pain occurs with each condition can help you identify your problem and get the care you need.


Appendicitis: Appendicitis pain usually happens around your belly button or mid-to-upper abdomen. It often moves to the right lower part of your abdomen. Within 12–24 hours after symptoms begin, the pain usually settles at McBurney's point, a place in the abdomen just above the appendix that is tender when touched if the appendix is inflamed. The pain may spread all over your abdomen if your appendix bursts.

Kidney stones: The location of kidney stone pain can change as the kidney stone moves from one position to another. It is likely to cause severe pain along your lower abdomen or groin. Kidney stone back pain can occur on either side of your lower back. Kidney stone pain can also happen along either side of your body, below your ribs. A vague abdominal pain, persistent stomachache, or kidney stone bloating may also occur.


Appendicitis: The intensity of appendicitis pain tends to be minor at first before becoming more severe over a few hours. Severe pain can begin suddenly, waking you from sleep. It may get worse when you cough or breathe deeply. The pain may differ from any other abdominal pain you had.

Kidney stones: The intensity of abdominal pain with kidney stones does not always align with the severity of your condition. You may not feel intense pain until the kidney stone has begun to pass through your urinary tract. Research indicates that some women consider the pain of kidney stones comparable to childbirth. In addition to comparable intensity, the pain may also occur in waves, similar to labor contractions.

Symptom Differences

Though intense pain can occur with either condition, appendicitis and kidney stones have some unique symptoms that help distinguish them.

Symptoms unique to appendicitis include:

Symptoms unique to kidney stones include:

  • Pain that occurs sporadically, subsiding over weeks
  • Pain or a burning sensation during urination
  • Frequent urination
  • Feeling like you urinate in small amounts or are unable to urinate completely
  • Brown, red, or pink urine, which occurs due to blood
  • Cloudy or smelly urine
  • Nausea caused by intense pain
  • Gas and constipation

Symptoms That Require Immediate Medical Care

Abdominal pain can occur due to serious conditions that can quickly become life-threatening. Seek immediate care if you have sudden and severe abdominal pain accompanied by any of the following symptoms:

Diagnosing Right-Sided Stomach Pain

Diagnosing abdominal pain can be challenging because of the many medical conditions that cause symptoms in this part of your body. If you think you have appendicitis or kidney stones, consult a healthcare provider as early as possible.

The following screenings are for accurately diagnosing right-sided stomach pain:

How Likely Is a Differential Diagnosis When Kidney Stone Pain Occurs?

Kidney stones are called "the great mimicker." Knowing what can mimic kidney stone pain can help identify this illness and other conditions like ovarian or testicular conditions, gastritis, and urinary tract infections with similar symptoms. Research indicates that CT scans provide the highest sensitivity of all imaging tests for accurately diagnosing abdominal pain with kidney stones.

Appendicitis Recovery

Recovery varies based on the treatment for appendicitis. Though removing the infected or inflamed appendix is the most common treatment, antibiotics, pain control, and follow-up can also treat some cases of appendicitis.

However, people with uncomplicated appendicitis or a high risk of surgery complications may be good candidates for treatment with antibiotic therapy. Appendectomy is advised for patients with complicated appendicitis, defined as one of the following conditions:

  • Perforated appendicitis
  • Periappendicular abscess
  • Peritonitis

Appendicitis can also occur due to an appendicolith—or an appendix stone. This occurs from a deposit of calcium and fecal debris that can become lodged in the appendix and cause a blockage.

Antibiotics vs. Surgery

You can relieve appendicitis symptoms with either antibiotics or surgery based on the cause of your condition. Both appendectomy and appendicitis treatment without surgery comes with pros and cons.


People who undergo antibiotic treatment receive intravenous (IV) antibiotics in the hospital for 24–72 hours to monitor them for worsening pain and clinical deterioration. IV therapy is followed by seven days of oral antibiotics administered at home.

Results from the Comparison of Outcomes of Antibiotic Drugs and Appendectomy (CODA), a large, randomized study of 25 U.S. centers, reported that antibiotics were non-inferior to treatment with appendectomy in the short term. Recuperation is faster with antibiotics.

However, the rate of recurrence for treatment with antibiotics is higher than for surgery. At 90 days, 30% of participants treated with antibiotics alone had undergone an appendectomy in the CODA study.


Recovery from an appendectomy varies based on the type of surgery performed. Laparoscopic surgery makes smaller incisions and is associated with faster recovery and fewer complications than open surgery. If you have laparoscopic surgery, you can usually return to work and your normal routine within one to three weeks. Recovery from open surgery can take from two to four weeks.

After you recover from an appendectomy, there is virtually no risk of recurrence. Rarely, patients may experience inflammation of the appendiceal stump, the remnant portion of the appendix left after surgery.

Kidney Stone Treatment

Kidney stone treatment depends on the stone's underlying cause, size, and location. Other factors such as age, other medical conditions, and overall wellness may also determine the suitable options for treating kidney stones. After the kidney stone is passed or surgically removed, the stone or its pieces are sent to a laboratory to determine the type of stone that formed.

Kidney stone treatment involves the following procedures:

  • Pass the kidney stone: You may be able to pass a kidney stone without medical intervention if the kidney stone is less than 5 millimeters in diameter. You will likely be advised to drink at least six to eight glasses of water to produce enough water to flush out the stone. The process can be painful, so pain medication may be prescribed. The timeline for passing a kidney stone can last from a few days up to about six weeks.
  • Medication: Some medications can help the stone pass by relaxing the ureter. The most common medications prescribed for this reason include Flomax (tamsulosin) to relax the ureter and help the stone pass, Zyloprim, Lopurin (allopurinol) for uric acid stones, antibiotics (for struvite stones), diuretics, phosphate solutions, and baking soda (sodium bicarbonate) or citric salt (sodium citrate).
  • Shock-wave lithotripsy: This is the most common type of kidney stone surgery. The technique uses high-energy shock waves to pulverize kidney stones into pieces as small as a grain of sand. The small stone fragments pass out of your body in your urine over a few weeks.
  • Ureteroscopy: A ureteroscopy is a procedure that involves passing a very small telescope, called a ureteroscope, into the urinary pathway. It passes through the urethra and bladder, up the ureter, and into the kidney to allow a urologist to see the stone. The ureteroscope allows the urologist to grab the stone and remove it. A laser may break up larger stones before they are removed.
  • Percutaneous nephrolithotomy: Percutaneous nephrolithotomy is a surgical procedure that involves using a nephroscope to view and remove the kidney stone. The tool enters your kidney through a small incision in your back. If the stone is large, high-frequency sound waves can break it into fragments. Suction removes the debris.


Finding the source of stomach pain can be challenging. Learning how to locate the cause of severe issues like appendicitis and kidney stones is not easy. These and many other severe problems have many of the same symptoms despite varying causes.

Appendicitis and kidney stones are often confused because they can both cause pain on the right side of the body, even though they affect different body systems. Appendicitis is an acute problem that occurs because of an inflamed appendix. A kidney stone is a chronic problem that starts when small masses form in your urinary tract. The effect of this impacts how you pass urine.

Knowing when to seek care for these problems can prevent your symptoms from becoming severe and life-threatening.

25 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. National Institute of Diabetes and Digestive and Kidney Diseases. The urinary tract & how it works.

  2. National Kidney Foundation. Kidney stones.

  3. Urology Care Foundation. What are kidney stones?

  4. Kaiser Permanente. Advice for people with uric acid stones.

  5. National Kidney Foundation. Struvite stones.

  6. National Organization for Rare Disorders. Cystinuria.

  7. Mount Sinai. Kidney stones.

  8. Shin S, Srivastava A, Alli NA, Bandyopadhyay BC. Confounding risk factors and preventative measures driving nephrolithiasis global makeup. World J Nephrol. 2018 Nov 24;7(7):129-142. doi:10.5527/wjn.v7.i7.129

  9. Vitetta L, Chen J, Clarke S. The vermiform appendix: an immunological organ sustaining a microbiome inoculumClin Sci (Lond). 2019;133(1):1-8. doi:10.1042/CS20180956

  10. Johns Hopkins Medicine. Appendicitis.

  11. Mount Sinai. Appendicitis.

  12. University of Maryland Medical System. Recognizing appendicitis: signs your sudden abdominal pain may be more serious.

  13. Keck Medicine of USC. Myth or fact: are kidney stones as painful as childbirth?

  14. American College of Emergency Physicians. Stomach pain.

  15. Brisbane W, Bailey MR, Sorensen MD. An overview of kidney stone imaging techniquesNat Rev Urol. 2016;13(11):654-662. doi:10.1038/nrurol.2016.154

  16. U.S. Pharmacist. Acute appendicitis in adults.

  17. Mariage M, Sabbagh C, Grelpois G, et al. Surgeon’s definition of complicated appendicitis: a prospective video survey studyEuroasian J Hepatogastroenterol. 2019;9(1):1-4. doi:10.5005/jp-journals-10018-1286

  18. Feldman LS, Lee L. Appendicoliths, antibiotic treatment failure, and appendectomy—is the glass half full or half empty? JAMA Surgery. 2022;157(3):e216901-e216901. doi:10.1001/jamasurg.2021.6901

  19. The CODA Collaborative. A randomized trial comparing antibiotics with appendectomy for appendicitisN Engl J Med. 2020;383(20):1907-1919. doi:10.1056/NEJMoa2014320

  20. Kaiser Permanente. Appendectomy: what to expect at home.

  21. Uludag M, Isgor A, Basak M. Stump appendicitis is a rare delayed complication of appendectomy: A case reportWorld J Gastroenterol. 2006;12(33):5401-5403. doi:10.3748/wjg.v12.i33.5401

  22. Washington University School of Medicine in St. Louis. Kidney stones overview.

  23. University of Michigan Health. Shockwave lithotripsy (SWL).

  24. National Kidney Foundation. Ureteroscopy.

  25. National Institute of Diabetes and Digestive and Kidney Diseases. Treatment for kidney stones.

By Anna Giorgi
Anna Zernone Giorgi is a writer who specializes in health and lifestyle topics. Her experience includes over 25 years of writing on health and wellness-related subjects for consumers and medical professionals, in addition to holding positions in healthcare communications.