## Overview
Stomach pain — clinically referred to as abdominal pain — is one of the most common symptoms encountered in both primary care and emergency medicine. It encompasses any discomfort felt between the chest and the pelvis, and can range from a dull, intermittent ache to severe, debilitating pain requiring emergency intervention. The International Classification of Diseases codes it under **ICD-10 R10** (abdominal and pelvic pain), with sub-codes specifying location (e.g., R10.1 for upper abdominal pain, R10.3 for lower abdominal pain).
Abdominal pain is the **single most common reason** for emergency department visits in the United States, accounting for approximately 11–12% of all ED presentations [1]. In primary care settings, it ranks among the top ten presenting complaints, with an estimated lifetime prevalence of functional abdominal pain disorders (such as irritable bowel syndrome) affecting 10–15% of the global adult population [2]. A 2014 systematic review found that abdominal pain in primary care is most often self-limiting, but roughly 10% of cases have an underlying organic cause requiring targeted treatment [3].
People search for information about stomach pain because it is nearly universal in experience yet highly variable in significance. Pain may originate from the gastrointestinal tract itself (visceral pain), the abdominal wall or peritoneum (somatic/parietal pain), or may be referred from extra-abdominal structures such as the heart or lungs. Understanding the character, location, timing, and associated features of abdominal pain is essential for determining whether self-care is appropriate or whether medical evaluation is needed.
> **Disclaimer:** This article is for informational purposes only and does not replace professional medical advice. If you are experiencing severe or persistent abdominal pain, consult a healthcare provider.
---
## Common Causes
Abdominal pain has a broad differential diagnosis. The following causes are organized roughly by frequency in adult primary care and emergency settings, with brief pathophysiology for each.
### 1. Functional Dyspepsia and Indigestion
The most common cause of recurrent upper abdominal pain without alarm features. Believed to involve visceral hypersensitivity, impaired gastric accommodation, and altered gastroduodenal motility. A 2017 American College of Gastroenterology (ACG) guideline estimates functional dyspepsia affects 15–20% of the Western population [4].
### 2. Irritable Bowel Syndrome (IBS)
A functional gastrointestinal disorder characterized by recurrent abdominal pain associated with altered bowel habits (diarrhea, constipation, or both). The pathophysiology involves gut-brain axis dysregulation, visceral hypersensitivity, altered intestinal microbiota, and low-grade mucosal inflammation. IBS affects approximately 11% of the global population [2].
### 3. Gastritis and Peptic Ulcer Disease
Inflammation of the gastric mucosa (gastritis) or mucosal erosion extending through the muscularis mucosae (ulcer). The two primary etiologies are *Helicobacter pylori* infection and nonsteroidal anti-inflammatory drug (NSAID) use. *H. pylori* disrupts the mucosal bicarbonate barrier, while NSAIDs inhibit prostaglandin synthesis, reducing mucosal blood flow and protective mucus secretion [5].
### 4. Gastroesophageal Reflux Disease (GERD)
Reflux of gastric acid into the esophagus, frequently perceived as epigastric or substernal pain ("heartburn"). Caused by transient lower esophageal sphincter relaxation, hiatal hernia, or impaired esophageal clearance.
### 5. Acute Gastroenteritis
Infection of the gastrointestinal tract by viruses (norovirus, rotavirus), bacteria (*Salmonella*, *Campylobacter*, *E. coli*), or parasites. Produces diffuse crampy abdominal pain with diarrhea and/or vomiting. Typically self-limited (24–72 hours).
### 6. Constipation
Infrequent or difficult passage of stool causing bloating, cramping, and left lower quadrant pain. Pathophysiology involves slow colonic transit, pelvic floor dysfunction, or inadequate dietary fiber and fluid intake.
### 7. Biliary Colic and Cholecystitis
Gallstones impacting the cystic duct produce episodic right upper quadrant pain (biliary colic). Persistent obstruction with secondary inflammation leads to acute cholecystitis. Pain is typically postprandial, lasting 30 minutes to several hours.
### 8. Appendicitis
Inflammation of the vermiform appendix, classically presenting as periumbilical pain migrating to the right lower quadrant (McBurney's point). Lifetime risk is approximately 7–8%. Obstruction of the appendiceal lumen (by fecalith, lymphoid hyperplasia) leads to bacterial overgrowth, mural ischemia, and potential perforation [1].
### 9. Urinary Tract and Renal Causes
Kidney stones (nephrolithiasis) cause severe, colicky flank pain radiating to the groin. Urinary tract infections may present with suprapubic discomfort. Pyelonephritis causes flank pain with fever.
### 10. Musculoskeletal / Abdominal Wall Pain
Often overlooked, abdominal wall pain (e.g., rectus sheath strain, anterior cutaneous nerve entrapment) can mimic visceral pathology. Carnett's sign (increased pain with abdominal wall tensing) helps distinguish this from intra-abdominal causes.
### Less Common but Important Causes
- **Pancreatitis** — epigastric pain radiating to the back, associated with alcohol use or gallstones
- **Mesenteric ischemia** — "pain out of proportion to exam" in elderly patients with vascular risk factors
- **Abdominal aortic aneurysm** — pulsatile abdominal mass with back pain
- **Small bowel obstruction** — colicky pain, distension, vomiting, absent flatus
- **Gynecological causes** — ectopic pregnancy, ovarian torsion, endometriosis
---
## RED FLAGS
The following signs and symptoms associated with abdominal pain warrant **immediate medical evaluation** (emergency department or call emergency services):
- **Sudden, severe ("thunderclap") abdominal pain** — may indicate perforation, aortic dissection, or ruptured aneurysm
- **Rigid, board-like abdomen** — suggests peritonitis
- **Hematemesis (vomiting blood) or melena (black, tarry stools)** — indicates upper GI bleeding
- **Hematochezia (bright red rectal bleeding)** with hemodynamic instability
- **Abdominal pain with fever > 38.5 °C (101.3 °F) and rigors**
- **Signs of shock**: tachycardia, hypotension, pallor, confusion, diaphoresis
- **Severe pain in a patient over 65** — higher risk for mesenteric ischemia, AAA, and atypical presentations of common conditions
- **Abdominal pain with positive pregnancy test** — ectopic pregnancy must be excluded
- **Inability to pass gas or stool** with progressive distension — suggests bowel obstruction
- **Pain radiating to the jaw, left arm, or shoulder** — atypical presentation of myocardial infarction, especially in women and diabetic patients
- **Recent abdominal surgery or procedure** with new-onset pain — anastomotic leak, abscess, or hemorrhage
- **Known history of aortic aneurysm** with new back or abdominal pain
---
## Self-Care at Home
For mild, non-alarming abdominal pain (no red flags above), the following evidence-based, non-pharmacological measures may provide relief:
### Dietary Modifications
- **Small, frequent meals** — reduces gastric distension and stimulates less acid secretion at each sitting
- **Avoid known triggers** — common culprits include spicy foods, fatty/fried foods, caffeine, alcohol, and carbonated beverages
- **BRAT diet** (bananas, rice, applesauce, toast) — traditionally recommended during gastroenteritis to reduce stool volume, though evidence is limited; bland foods are generally better tolerated
- **Adequate fiber intake** (25–30 g/day) — beneficial for constipation-related pain; increase gradually to avoid bloating [2]
### Hydration
- **Oral rehydration** — critical in gastroenteritis. Oral rehydration solutions (ORS) containing glucose and electrolytes are preferred over plain water for significant fluid losses
- Avoid excessive alcohol and caffeine, which can worsen gastritis and dehydration
### Physical and Behavioral Measures
- **Heat therapy** — a warm compress or heating pad applied to the abdomen for 15–20 minutes may relieve cramping by promoting smooth muscle relaxation. A small randomized trial found continuous low-level topical heat was comparable to ibuprofen for menstrual-related abdominal pain
- **Rest and positioning** — lying on the left side with knees drawn up (fetal position) can reduce pressure on the bowel and may alleviate gas-related discomfort
- **Stress management** — the gut-brain axis is well-established; psychological stress exacerbates functional GI pain. Techniques such as diaphragmatic breathing, progressive muscle relaxation, and cognitive behavioral therapy (CBT) have demonstrated efficacy for IBS symptoms [2]
- **Peppermint oil (enteric-coated capsules)** — a 2019 Cochrane-quality meta-analysis found peppermint oil significantly improved global IBS symptoms and abdominal pain versus placebo, likely through calcium channel antagonism in intestinal smooth muscle [6]
### What to Avoid
- Do **not** apply a heating pad to the abdomen if appendicitis or another surgical cause is suspected
- Avoid NSAIDs (ibuprofen, naproxen) if gastritis or ulcer is likely — they may worsen mucosal injury
- Do not take laxatives for abdominal pain of unknown cause
---
## OTC Medications That Help
Over-the-counter medications can be appropriate for mild to moderate abdominal symptoms without red flags. Always read package labeling and follow recommended doses.
| Class | Example(s) | Typical Adult Dose | Notes / Contraindications |
|---|---|---|---|
| **Antacids** | Calcium carbonate (Tums), Magnesium hydroxide / Aluminum hydroxide (Maalox) | 500–1000 mg calcium carbonate as needed (max 7500 mg/day) | Rapid symptom relief by neutralizing gastric acid. Calcium-based products may cause constipation; magnesium-based may cause diarrhea. Avoid in renal impairment. |
| **H2-Receptor Antagonists** | Famotidine (Pepcid AC) | 10–20 mg once or twice daily | Reduces gastric acid secretion. Onset ~30 min. Generally well tolerated. Preferred over ranitidine (withdrawn from market due to NDMA concerns — FDA 2020). |
| **Proton Pump Inhibitors (OTC)** | Omeprazole (Prilosec OTC), Esomeprazole (Nexium 24HR) | 20 mg once daily for up to 14 days | Most potent acid suppression. Takes 1–3 days for full effect. Not for immediate relief. Should not be used beyond 14 days without medical supervision. Risk of *C. difficile*, hypomagnesemia, and B12 deficiency with long-term use [5]. |
| **Simethicone** | Gas-X, Mylicon | 40–125 mg after meals and at bedtime (max 500 mg/day) | Anti-foaming agent that coalesces gas bubbles. No systemic absorption. Very safe but limited evidence of efficacy for functional bloating. |
| **Bismuth subsalicylate** | Pepto-Bismol | 524 mg every 30–60 min as needed (max 8 doses/day) | Antimicrobial, anti-inflammatory, and antisecretory effects. Useful for traveler's diarrhea and mild dyspepsia. **Avoid** in salicylate allergy, children (Reye syndrome risk), and patients on anticoagulants. |
| **Loperamide** | Imodium A-D | 4 mg initially, then 2 mg after each loose stool (max 16 mg/day) | Mu-opioid receptor agonist in gut wall; slows motility. For diarrhea-associated cramping only. **Do not use** in bloody diarrhea or suspected *C. difficile*. |
| **Fiber supplements** | Psyllium (Metamucil), Methylcellulose (Citrucel) | Psyllium: 1 rounded tsp (≈3.4 g) in 8 oz water, 1–3 times daily | Bulking agents for constipation-related pain. Increase dose gradually. Ensure adequate fluid intake. |
| **Osmotic laxatives** | Polyethylene glycol (MiraLAX) | 17 g in 8 oz water once daily | For constipation. Onset 1–3 days. Well tolerated; generally safe for short-term use. |
> **Important:** OTC medications should be used for short-term symptom management. If symptoms persist beyond 2 weeks or worsen, medical evaluation is recommended.
---
## Prescription Options
Prescription therapy is indicated when OTC measures fail, when a specific diagnosis is established, or when the severity of symptoms requires targeted pharmacologic intervention. These medications should only be taken under medical supervision.
| Class | Example(s) | Indication | Notes |
|---|---|---|---|
| **Prescription PPIs** | Omeprazole 40 mg, Pantoprazole 40 mg, Lansoprazole 30 mg | GERD, peptic ulcer disease, *H. pylori* eradication (as part of triple/quadruple therapy) | Higher doses and longer courses than OTC. Monitor for long-term complications. |
| **H. pylori eradication therapy** | Clarithromycin triple therapy (PPI + clarithromycin + amoxicillin) or Bismuth quadruple therapy | Confirmed *H. pylori* infection | Treatment duration 10–14 days. Antibiotic resistance is increasing; susceptibility-guided therapy preferred where available [5]. |
| **Antispasmodics** | Hyoscine butylbromide (Buscopan), Dicyclomine (Bentyl) | IBS-related cramping, biliary colic | Anticholinergic side effects (dry mouth, urinary retention, blurred vision). Avoid in glaucoma and prostatic hypertrophy. |
| **Tricyclic antidepressants (low-dose)** | Amitriptyline 10–25 mg at bedtime | Functional abdominal pain, IBS (pain-predominant) | Neuromodulatory effect on visceral pain processing. Not used as an antidepressant at these doses. Gradual titration. Prescribing physician: gastroenterologist or primary care [4]. |
| **SSRIs / SNRIs** | Duloxetine, Citalopram | Functional GI pain with comorbid anxiety/depression | May improve global symptoms through central pain modulation. Prescribed by primary care or psychiatry. |
| **Rifaximin** | Xifaxan 550 mg TID x 14 days | IBS with diarrhea (IBS-D) | Non-absorbable antibiotic that modulates gut microbiome. FDA-approved for IBS-D. May need repeat courses [2]. |
| **Linaclotide / Plecanatide** | Linzess 145–290 mcg daily | IBS with constipation (IBS-C), chronic idiopathic constipation | Guanylate cyclase-C agonist. Increases intestinal fluid secretion. Take on empty stomach 30 min before first meal. |
| **Ursodeoxycholic acid** | Ursodiol 8–10 mg/kg/day | Gallstone dissolution (selected patients), biliary pain | For cholesterol gallstones in non-surgical candidates. Dissolves stones slowly over 6–24 months. |
| **Pancreatic enzyme replacement** | Creon (pancrelipase) | Exocrine pancreatic insufficiency (chronic pancreatitis) | Dose titrated to fat intake. Prescribed by gastroenterologist. |
---
## Lab Tests Typically Ordered
When abdominal pain requires medical evaluation, clinicians use laboratory and imaging studies to narrow the differential diagnosis. The specific tests ordered depend on the pain's location, character, and clinical context [1][7].
| Test | Rationale |
|---|---|
| **Complete Blood Count (CBC)** | Evaluate for infection (elevated WBC), anemia (GI blood loss), thrombocytosis (inflammation). See [CBC test](/tests/complete-blood-count). |
| **Comprehensive Metabolic Panel (CMP)** | Assess electrolytes, renal function (BUN/creatinine), liver enzymes (AST, ALT), bilirubin, and glucose. Abnormal liver enzymes suggest hepatobiliary pathology. See [CMP test](/tests/comprehensive-metabolic-panel). |
| **Lipase** | Elevated > 3× upper limit of normal is diagnostic for acute pancreatitis. More specific than amylase. See [Lipase test](/tests/lipase). |
| **Urinalysis** | Screen for UTI, kidney stones (hematuria), or diabetic ketoacidosis (ketonuria). See [Urinalysis test](/tests/urinalysis). |
| **C-Reactive Protein (CRP) / ESR** | Non-specific inflammatory markers. Useful for differentiating functional from organic disease and monitoring inflammatory bowel disease. See [CRP test](/tests/c-reactive-protein). |
| **Stool studies** | Fecal calprotectin (distinguishes IBD from IBS), stool culture, ova and parasites, *C. difficile* toxin, fecal occult blood test (FOBT). See [Fecal calprotectin test](/tests/fecal-calprotectin). |
| **Urine/serum pregnancy test (beta-hCG)** | **Mandatory** in all women of reproductive age with abdominal pain to exclude ectopic pregnancy. See [Pregnancy test](/tests/pregnancy-test-hcg). |
| ***H. pylori* testing** | Urea breath test or stool antigen test if dyspepsia is present. Serology is less preferred (cannot distinguish active from past infection) [5]. |
| **Celiac panel** | Tissue transglutaminase (tTG-IgA) with total IgA. Consider in chronic abdominal pain with diarrhea, weight loss, or iron deficiency. See [Celiac panel](/tests/celiac-panel). |
| **Lactate** | Elevated in mesenteric ischemia, sepsis, or bowel necrosis. An important test when ischemia is suspected. |
### Imaging
- **Abdominal ultrasound** — first-line for right upper quadrant pain (gallstones, cholecystitis) and in pregnancy
- **CT abdomen/pelvis with contrast** — gold standard for acute abdominal pain evaluation in the ED; high sensitivity for appendicitis, diverticulitis, obstruction, and perforation [7]
- **Abdominal X-ray** — useful for bowel obstruction (air-fluid levels) and free air (perforation), though largely superseded by CT
- **Upper endoscopy (EGD)** — indicated for persistent dyspepsia with alarm features, GI bleeding, or failed empiric therapy
- **Colonoscopy** — indicated for lower GI bleeding, change in bowel habits in patients ≥ 45, or positive fecal immunochemical test (FIT)
---
## Special Populations
### Children and Adolescents
Abdominal pain is extremely common in children, with functional abdominal pain disorders (per Rome IV criteria) affecting up to 13.5% of school-age children. Key considerations:
- **Intussusception** (typically 6 months – 3 years) — "currant jelly" stools, intermittent severe colicky pain, lethargy
- **Appendicitis** — peak incidence in ages 10–19; atypical presentations more common in younger children
- **Functional abdominal pain** — diagnosis of exclusion; reassurance, dietary modifications, and psychological therapies (hypnotherapy, CBT) are first-line
- **Medication dosing** — pediatric doses for OTC medications must follow age- and weight-based guidelines on product labeling. **Always consult a pediatrician before administering medications to children**, particularly under age 12. Bismuth subsalicylate is **contraindicated** in children and adolescents due to Reye syndrome risk.
- Proton pump inhibitors are FDA-approved for children aged ≥ 1 year for specific indications (GERD, erosive esophagitis) at weight-based dosing — only under physician guidance.
### Pregnancy
Abdominal pain in pregnancy demands careful evaluation because of overlapping obstetric and non-obstetric etiologies:
- **First trimester**: always exclude ectopic pregnancy; round ligament pain is common and benign
- **Second/third trimester**: consider preeclampsia (RUQ pain + hypertension + proteinuria), HELLP syndrome, placental abruption, and preterm labor
- **Medication safety**:
- **Acetaminophen** — generally considered safe across all trimesters (FDA former Category B)
- **NSAIDs** — avoid after 20 weeks' gestation due to risk of premature ductus arteriosus closure and oligohydramnios (FDA warning, 2020)
- **PPIs** — omeprazole was former FDA Category C; newer data generally support safety, but use only when clearly needed. Famotidine may be preferred as first-line acid suppression
- **Bismuth subsalicylate** — **contraindicated** in pregnancy (salicylate component)
- **Antispasmodics** — limited safety data; use only under obstetric guidance
- ACOG recommends that **any pregnant patient with acute abdominal pain should be evaluated promptly** by a healthcare provider; imaging (starting with ultrasound) should not be delayed when indicated
### Elderly (≥ 65 years)
Older adults present unique challenges:
- **Atypical presentations** — pain may be less severe despite serious pathology (e.g., painless perforation in patients on corticosteroids, mild tenderness in mesenteric ischemia)
- **Higher mortality** — acute abdominal conditions carry 6–8× higher mortality in the elderly compared to younger adults [1]
- **Polypharmacy** — NSAIDs, anticoagulants, and corticosteroids increase risk of GI bleeding. Medication reconciliation is essential
- **Vascular causes** — mesenteric ischemia should be considered in any elderly patient with "pain out of proportion to examination," especially those with atrial fibrillation, heart failure, or peripheral vascular disease
- **Lower threshold for imaging** — CT scanning is generally recommended earlier in the workup for elderly patients with acute abdominal pain [7]
- PPIs and H2 blockers are generally well tolerated but may interact with clopidogrel (omeprazole) or require renal dose adjustment (famotidine)
### Athletes
- **Exercise-related transient abdominal pain (ETAP)** — commonly known as a "side stitch." Mechanism may involve diaphragmatic ischemia or peritoneal ligament traction. Usually benign and self-limiting; slowing pace and deep breathing typically provide relief
- **Runner's diarrhea / GI distress** — affects up to 30–50% of endurance athletes due to reduced splanchnic blood flow during exercise. Prevention: avoid high-fiber and high-fat meals 2–3 hours before exercise, ensure adequate hydration, and consider training the gut with carbohydrate intake during exercise
- **NSAID use** — athletes frequently use NSAIDs for musculoskeletal pain; this significantly increases risk of GI mucosal injury, especially when combined with exercise-induced splanchnic hypoperfusion. Use acetaminophen as an alternative when appropriate
- **Abdominal wall injuries** — rectus abdominis strain, sports hernia (athletic pubalgia) should be considered in athletes with exertional lower abdominal pain
---
## When to Escalate
Use the following decision framework to guide when to seek medical attention. When in doubt, always err on the side of earlier evaluation.
### Call 911 / Go to the Emergency Room Immediately
- Any red flag symptom listed above (rigid abdomen, signs of shock, hematemesis, etc.)
- Severe, sudden-onset pain that is the worst you have ever experienced
- Abdominal pain with fainting, chest pain, or difficulty breathing
- Abdominal pain with known or suspected pregnancy
- Abdominal pain after significant trauma
### Urgent Care / Same-Day GP Visit
- Moderate pain lasting > 24 hours without improvement
- Pain with persistent vomiting (unable to keep fluids down for > 12 hours)
- Fever > 38 °C (100.4 °F) with abdominal pain
- Pain localized to the right lower quadrant or right upper quadrant
- Painful or bloody urination
- New-onset constipation lasting > 3 days with pain and distension
### Scheduled GP / Primary Care Appointment (within 1–2 weeks)
- Recurrent or chronic abdominal pain (> 4 weeks) interfering with daily activities
- Unintentional weight loss associated with abdominal symptoms
- Change in bowel habits lasting > 2 weeks (new constipation or diarrhea)
- Persistent heartburn or dyspepsia not responding to 2 weeks of OTC treatment
- Family history of GI cancers (colon, gastric, pancreatic) with new symptoms
- Age ≥ 45 with new-onset abdominal symptoms (screening colonoscopy may be indicated per USPSTF guidelines)
### General Guideline
If you are unsure whether your symptoms require urgent evaluation, contact your healthcare provider or a nurse helpline. It is always better to be assessed and reassured than to delay evaluation of a potentially serious condition.
---
## References
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[2] Hungin APS, Whorwell PJ, Tack J, Mearin F. The prevalence, patterns and impact of irritable bowel syndrome: an international survey of 40,000 subjects. *Aliment Pharmacol Ther*. 2003;17(5):643-650. PMID:12641512.
[3] Viniol A, Keez S, Becker A, et al. Studies of the symptom abdominal pain — a systematic review and meta-analysis. *Fam Pract*. 2014;31(5):517-529. PMID:24987023.
[4] Moayyedi PM, Lacy BE, Andrews CN, Enns RA, Howden CW, Vakil N. ACG and CAG Clinical Guideline: Management of Dyspepsia. *Am J Gastroenterol*. 2017;112(7):988-1013. PMID:28631728.
[5] Lanas A, Chan FKL. Peptic ulcer disease. *Lancet*. 2017;390(10094):613-624. PMID:28242110.
[6] Alammar N, Wang L, Saberi B, et al. The impact of peppermint oil on the irritable bowel syndrome: a meta-analysis of the pooled clinical data. *BMC Complement Altern Med*. 2019;19(1):21. PMID:30654773.
[7] Gans SL, Pols MA, Stoker J, Boermeester MA. Guideline for the diagnostic pathway in patients with acute abdominal pain. *Dig Surg*. 2015;32(1):23-31. PMID:25659265.
[8] U.S. Food and Drug Administration. FDA Drug Safety Communication: FDA advises avoiding use of NSAIDs in pregnancy at 20 weeks or later. October 2020. Available at: www.fda.gov/drug-safety-communications.
[9] National Institute for Health and Care Excellence (NICE). Irritable bowel syndrome in adults: diagnosis and management [CG61]. 2008 (updated 2017). Available at: www.nice.org.uk/guidance/cg61.
[10] Peery AF, Crockett SD, Barritt AS, et al. Burden of Gastrointestinal, Liver, and Pancreatic Diseases in the United States. *Gastroenterology*. 2015;149(7):1731-1741. PMID:26327134.
