Compare conditions

Put any two — or three — conditions side by side, adult or pediatric, to spot the look-alike differences fast, row by row.

Irritable Bowel Syndrome

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In one line

·Belly pain that comes back again and again, paired with a change in how often you poop or what your poop looks like, lasting more than 3 months, with no warning signs of bleeding, weight loss, or serious disease.

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Normal physiology

·The gut is a long, muscular tube that squeezes food and waste along in smooth waves (peristalsis), guided by a two-way conversation between the enteric nervous system (the gut's own nerve network in the intestinal wall) and the brain via the vagus nerve (the main cable running between gut and brain), with stretch and chemical sensors in the gut lining quietly reporting normal movement so you never feel ordinary digestion.

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What goes wrong

·In IBS, the wiring between the gut and brain fires too loudly. The enteric nervous system and vagus nerve send pain signals for normal gut stretching that should feel like nothing. Serotonin floods the gut lining, cranking up wave speed and pain sensitivity. Mast cells (immune sentries in the gut wall) release extra histamine and inflammatory molecules, turning the volume even higher. The gut microbiome shifts toward bacteria that produce more gas and fewer calming short-chain fatty acids. Stress hormones like cortisol (the body's main stress chemical) and corticotropin-releasing factor (a brain alarm peptide) dial up gut nerve firing even more. The result: normal digestion feels painful, and gut squeezing goes too fast (diarrhea), too slow (constipation), or swings between both.

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Hallmark signs

·Belly pain that comes and goes, often tied to when you poop
·Bloating or feeling full of gas
·Diarrhea (loose, watery stools)
·Constipation (hard, lumpy stools or trouble going)
·Mixed bowel habits (some days diarrhea, some days constipation)
·Mucus (clear or white slime) in the stool
·Feeling like you didn't empty all the way after a bowel movement
·Symptoms get worse with stress or certain foods

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Red flags · escalate now

·Blood in the stool or black, tarry stools
·Losing weight without trying
·Fever or night sweats
·Severe pain that wakes you up at night or doesn't improve after a bowel movement
·New symptoms starting after age 50

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Workup

·Complete blood count (CBC)
·C-reactive protein (CRP) and fecal calprotectin
·Tissue transglutaminase IgA (tTG-IgA) with total IgA
·Stool studies (culture, ova and parasites, Giardia antigen)
·Thyroid-stimulating hormone (TSH)
·Colonoscopy (if over 45, has alarm features, or family history of colon cancer)

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Treatment

·Rome IV criteria check plus ruling out red flags (blood in stool, weight loss, fever, family history of colon cancer, age over 50 with new symptoms)
·Low FODMAP diet for four to six weeks, then bring foods back one at a time
·Antispasmodic medicine (dicyclomine 20 mg, hyoscyamine 0.125 mg, or peppermint oil 180 mg) before meals
·Selective serotonin reuptake inhibitor (like sertraline 25–50 mg daily) or tricyclic antidepressant (like amitriptyline 10–25 mg at bedtime) at low dose
·Symptom-specific agents: loperamide 2 mg for diarrhea-irritable bowel syndrome, linaclotide 145–290 mcg or plecanatide 3 mg for constipation-irritable bowel syndrome, rifaximin 550 mg three times daily for ten days if bacterial overgrowth suspected
·Cognitive behavioral therapy or gut-directed hypnotherapy, weekly sessions for eight to twelve weeks
·Soluble fiber (like psyllium 5–10 grams daily) for constipation-irritable bowel syndrome

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NCLEX trap

·In irritable bowel syndrome (IBS), the first step is a careful story and exam to check for red flags—blood in stool, fever, weight loss, new onset after age 50, or family history of colon cancer. If none of those are present, imaging does NOT help and costs money without changing care. IBS is a gut-brain wiring problem, not a structural break you can see on a scan.
·IBS is NOT an infection. It is a functional disorder—the gut nerves send pain signals too loudly and the brain reads them wrong, like a fire alarm going off when someone burns toast. Antibiotics do not fix wiring problems. The real fixes are diet changes (like low-FODMAP), stress relief, antispasmodics (to calm gut muscle spasms), and sometimes low-dose tricyclic antidepressants (to turn down pain volume). Antibiotics are only used in rare cases of small intestinal bacterial overgrowth (SIBO), confirmed by breath testing.
·IBS is a diagnosis of exclusion—you MUST rule out dangerous mimics first. Check tissue transglutaminase (tTG-IgA) for celiac disease, fecal calprotectin for inflammatory bowel disease (Crohn's or ulcerative colitis), complete blood count (CBC) for anemia, and thyroid-stimulating hormone (TSH) for thyroid problems. Missing celiac or IBD can lead to serious harm like malnutrition, bleeding, or cancer.
·IBS treatment must match the subtype and the broken step. Start with first-line non-drug fixes: low-FODMAP diet (cuts fermentable sugars that feed gut bacteria and cause gas), soluble fiber (like psyllium), and stress management (deep breathing, cognitive behavioral therapy). Then add targeted medicines: antispasmodics (like dicyclomine or hyoscyamine) for cramping pain, loperamide for diarrhea-predominant IBS, or linaclotide or lubiprostone for constipation-predominant IBS. Each tool must fit the specific problem.
·The pain in IBS is REAL. The gut has its own nervous system (the enteric nervous system, like a second brain in your belly) that talks to your actual brain through the vagus nerve (the main wire connecting gut to brain). In IBS, this conversation is too loud—normal gut stretch feels like sharp pain, and stress from the brain amps up gut cramping. A normal exam does NOT mean fake pain. Validate what the patient feels, explain the gut-brain wiring problem in plain words, and build trust so treatment can work.
·One normal basic metabolic panel (BMP) does NOT prove IBS. You must also rule out celiac (tTG-IgA), inflammatory bowel disease (fecal calprotectin, and sometimes colonoscopy if red flags are present), thyroid problems (TSH), and infections (stool culture if diarrhea is new or severe). Then apply Rome IV criteria: belly pain at least one day per week for three months, linked to pooping, with change in stool frequency or form. Only after excluding dangerous diseases can you confidently diagnose IBS.

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