Wegovy Diarrhea: Causes, Duration & How to Stop It
Everything you need to know about diarrhea on semaglutide—why it happens, how long it lasts, which foods trigger it, medications that work, and when it's time to call your doctor.
The Short Answer
Diarrhea affects 8-9% of people on Wegovy and is usually worst during the first few weeks or after dose increases. For most people, it improves significantly within 4-6 weeks as your body adjusts.
Key facts:
- How common: 8-9% in clinical trials (more common at higher doses)
- Peak timing: First 2-4 weeks or after dose increases
- Duration: Usually improves by week 4-6; persistent cases last 3+ months
- Most effective solution: Low-fat, low-fiber diet during flares + Imodium as needed
Why Wegovy Causes Diarrhea
Semaglutide affects your digestive system in several ways, all of which can trigger diarrhea:
1. Slowed Gastric Emptying (Main Mechanism)
This is how GLP-1 medications work: They slow the rate at which food leaves your stomach. This keeps you full longer, but it also means food sits in your digestive tract longer.
When food moves slowly through the stomach but then hits the small intestine, your body can overcompensate by speeding up intestinal transit—resulting in diarrhea. Essentially, your gut hasn't calibrated the new, slower rhythm yet.
2. Changes in Gut Motility
GLP-1 receptors are found throughout your intestines. Semaglutide activates these receptors, which can alter the normal contractions (peristalsis) that move food through your digestive system. This can cause irregular bowel movements—sometimes constipation, sometimes diarrhea.
3. Altered Bile Acid Metabolism
GLP-1 medications affect how your body processes bile acids (digestive fluids that break down fats). When bile acid regulation is disrupted, excess bile can spill into the colon, causing bile acid diarrhea—characterized by:
- Urgent, watery stools
- Especially after eating fatty foods
- Yellow or green-tinged stools
4. Changes in Gut Microbiome
Rapid changes in diet (eating less food, different food choices) can temporarily disrupt your gut bacteria balance. This microbiome shift can cause digestive symptoms including diarrhea until your gut flora adapts.
5. Increased Fat Malabsorption
When digestion slows down, your body may not absorb fats as efficiently. Unabsorbed fat in the colon draws in water (osmotic effect) and causes loose, greasy stools (steatorrhea).
6. Dietary Changes
Many people drastically change their eating habits on Wegovy:
- Increasing protein and fiber (can cause loose stools if done too quickly)
- Using sugar alcohols in "low-carb" foods (maltitol, sorbitol—major diarrhea triggers)
- Drinking more coffee (caffeine stimulates bowels)
- Eating more artificial sweeteners (can cause diarrhea)
IMPORTANT:
Diarrhea on Wegovy is not caused by the medication being "toxic" or damaging your intestines. It's a functional side effect from how semaglutide changes digestive timing and motility. This is why it usually improves as your body adapts.
What Do Clinical Trials Show?
STEP Trials (Wegovy for Weight Loss)
Data from over 4,500 patients taking Wegovy:
- Diarrhea incidence: 8.3% on Wegovy vs 5.0% on placebo
- Dose-dependent: More common at 1.7mg and 2.4mg doses (vs lower doses)
- Severity: Most cases were mild to moderate (severe: <1%)
- Discontinuation: Only 0.4% stopped treatment due to diarrhea
- Timing: Peak incidence in first 4-8 weeks, then declined
Real-World Data
Studies following actual patients (not just clinical trials) show:
- Higher real-world incidence: 12-15% report diarrhea (vs 8% in trials—likely due to less dietary support)
- Resolution rate: 70% improve significantly by 6-8 weeks
- Persistent cases: 30% have ongoing issues requiring management
- Trigger foods: High-fat meals most commonly reported trigger
Timeline: When Diarrhea Starts and Stops
Week 1-2: Initial Dose
Most common onset period. Your digestive system is adjusting to slowed motility. Diarrhea may be intermittent—some days fine, others not. Usually triggered by certain foods (especially fatty meals).
Week 3-4: Adaptation Phase
For many people, symptoms start improving as your gut adapts. However, if you increase your dose during this time, symptoms may worsen again temporarily.
Week 5-8: Resolution for Most
70% of people see significant improvement by this point. Diarrhea becomes less frequent, less severe, or resolves entirely. You've likely identified trigger foods and your gut has adapted to the medication.
Month 3+: Persistent Cases
30% have ongoing issues. If diarrhea continues beyond 3 months at same dose, it's unlikely to resolve on its own. Options:
- Lower your dose (may reduce symptoms while maintaining some weight loss benefit)
- Use daily anti-diarrheal medication
- Strict dietary modifications
- Consider switching to different GLP-1 (tirzepatide may cause less diarrhea for some)
After Dose Increases
Expect a 7-14 day flare after each dose increase. Your body needs to re-adapt to the higher medication level. This is normal and doesn't mean you're going backwards.
Foods That Trigger Diarrhea on Wegovy
Certain foods are much more likely to cause diarrhea when you're on semaglutide:
High-Fat Foods
Why they trigger diarrhea: Fat is harder to digest when gastric emptying is delayed. Undigested fat reaches the colon and causes osmotic diarrhea.
Worst offenders:
- Fried foods (french fries, fried chicken, donuts)
- Fast food burgers and pizza
- Cream-based sauces and soups
- Full-fat dairy (whole milk, heavy cream, ice cream)
- Fatty cuts of meat (ribeye, pork belly, bacon)
- Butter and oils in excess
Sugar Alcohols (Especially in "Keto" Products)
Why they trigger diarrhea: These artificial sweeteners are poorly absorbed and draw water into your intestines (osmotic laxative effect).
Avoid these ingredients:
- Maltitol (worst offender—common in sugar-free candy)
- Sorbitol (sugar-free gum, candies)
- Xylitol (gum, mints)
- Erythritol (usually better tolerated, but can still cause issues in excess)
Hidden sources: "Low-carb" protein bars, sugar-free desserts, keto ice cream.
Excess Fiber (If Increased Too Quickly)
Why it triggers diarrhea: Sudden increase in fiber (especially insoluble fiber) speeds up bowel transit. Combined with Wegovy's effects, this can cause loose stools.
Problematic if eaten in large amounts:
- Raw vegetables (broccoli, cauliflower, kale in large amounts)
- Beans and lentils (especially if not used to eating them)
- Whole grains (bran cereals, high-fiber bread)
- Berries in excess (1+ cup at once)
Note: Fiber is healthy! Just increase gradually (5g per week) rather than jumping from 10g to 40g daily.
Other Common Triggers:
- Coffee: Caffeine stimulates bowel contractions (2+ cups can trigger diarrhea)
- Spicy foods: Can irritate already-sensitive GI tract
- Dairy (if lactose intolerant): Lactose intolerance often worsens on GLP-1s
- Artificial sweeteners: Aspartame, sucralose in excess
- Alcohol: Irritates gut and impairs digestion
- Greasy/oily foods: Salmon, avocado, nuts in large portions
How to Stop or Reduce Diarrhea on Wegovy
1. Follow a Low-Fat, Low-Fiber "Gentle" Diet During Flares
When diarrhea is active, temporarily switch to easily digestible foods:
SAFE FOODS (Low-fat, low-fiber):
- Lean proteins: Skinless chicken breast, turkey, white fish, eggs (no butter)
- Simple carbs: White rice, white bread, plain pasta, crackers
- Cooked vegetables: Peeled potatoes, carrots, zucchini (well-cooked, no skin)
- Bananas: Binding effect, replaces potassium
- Applesauce: Pectin helps firm stools
- Oatmeal: Soluble fiber (gentler than insoluble)
- Low-fat yogurt: Probiotics may help (choose plain, unsweetened)
AVOID DURING FLARES:
- All fried foods
- High-fat meats and dairy
- Raw vegetables and salads
- Whole grains and high-fiber cereals
- Beans, lentils, nuts
- Spicy foods
- Coffee (or limit to 1 cup)
2. Over-the-Counter Anti-Diarrheal Medications
Imodium (Loperamide) - FIRST LINE
How it works: Slows intestinal contractions, allowing more water absorption.
Dosing: 2mg (1 caplet) after first loose stool, then 1mg after each subsequent loose stool (max 8mg/day).
Best for: Acute diarrhea, occasional use. Safe to use regularly if needed, but talk to doctor if using daily for >2 weeks.
Pepto-Bismol (Bismuth Subsalicylate)
How it works: Reduces inflammation in intestines, has mild antibacterial effect.
Dosing: 2 tablets (262mg each) every 30-60 minutes as needed (max 8 doses/24 hours).
Best for: Mild diarrhea with nausea. Note: Turns stool black (normal, not blood).
Fiber Supplements (Psyllium - Metamucil)
How it works: Soluble fiber absorbs excess water and bulks stool (can help both diarrhea AND constipation).
Dosing: 1 tsp (5g) in 8oz water, 1-2x daily.
Best for: Chronic, ongoing diarrhea. Takes 2-3 days to see effect.
3. Prescription Medications (If OTC Doesn't Work)
Talk to your doctor about:
- Cholestyramine (Questran): Bile acid sequestrant—very effective for bile acid diarrhea (the yellow/green watery type). Dose: 4g powder 1-2x daily.
- Prescription loperamide: Higher doses than OTC (up to 16mg daily under supervision).
- Dicyclomine (Bentyl): Antispasmodic that reduces intestinal cramping and urgency.
4. Stay Aggressively Hydrated
Critical: Diarrhea causes rapid fluid and electrolyte loss.
- Drink 10-12 oz water after every loose stool
- Use oral rehydration solutions: Pedialyte, Liquid IV, LMNT (contains sodium, potassium, glucose for absorption)
- Avoid: Sugary drinks, alcohol, excessive caffeine (all worsen diarrhea)
- Monitor urine: Should be pale yellow. Dark urine = dehydrated.
5. Probiotics
Evidence is mixed, but some people find relief. Look for:
- Lactobacillus rhamnosus GG
- Saccharomyces boulardii (especially effective for antibiotic-related diarrhea)
- Multi-strain formulas with 10+ billion CFUs
Give it 2-4 weeks to see if it helps. If no improvement, discontinue.
6. Adjust Medication Timing
Some people find that injecting at night (instead of morning) reduces daytime diarrhea, since peak GI effects occur 24-48 hours post-injection. Experiment to see what works for you.
When to Call Your Doctor vs. When to Go to the ER
Most diarrhea on Wegovy is annoying but not dangerous. However, watch for these warning signs:
GO TO ER IMMEDIATELY IF:
- Severe dehydration signs: Dizziness when standing, very dark urine, confusion, rapid heartbeat
- Blood in stool (red blood or black, tarry stools)
- Severe abdominal pain (not just cramping)
- High fever (>101.5°F with diarrhea)
- Inability to keep down fluids (vomiting + diarrhea)
- Diarrhea lasting >3 days with severe volume loss (>10 episodes/day)
CALL YOUR DOCTOR IF:
- Diarrhea lasting >2 weeks despite dietary changes
- Significant weight loss from diarrhea (not intentional weight loss)
- Diarrhea interfering with work or daily activities
- Nighttime diarrhea (waking you from sleep)
- Mucus in stool regularly
- Persistent abdominal cramping
- OTC medications not helping
IMPORTANT: Rule Out Other Causes
If diarrhea is severe or persistent, your doctor should rule out:
- C. diff infection (especially if recent antibiotics)
- Celiac disease (can be triggered by dietary changes)
- Inflammatory bowel disease (Crohn's, ulcerative colitis)
- Pancreatic insufficiency (not digesting fats properly)
- Bile acid malabsorption
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Frequently Asked Questions
How long does diarrhea last on Wegovy?
For most people, diarrhea is worst in the first 2-4 weeks or after dose increases and improves significantly by week 6-8. About 70% see resolution or major improvement within 2 months. The remaining 30% may have persistent symptoms requiring ongoing management or dose adjustment.
Can I take Imodium every day while on Wegovy?
Yes, daily Imodium is generally safe for chronic diarrhea, but you should discuss with your doctor if you're using it for more than 2 weeks. Some people need it daily during the first few months of treatment. However, it's better to address the root cause through diet modification rather than relying solely on medication long-term.
Should I lower my Wegovy dose if I have persistent diarrhea?
Talk to your doctor, but yes, temporarily lowering your dose can help. Many people find that reducing from 2.4mg to 1.7mg (or from 1.7mg to 1.0mg) significantly improves diarrhea while still providing weight loss benefits. You can try the lower dose for 4-6 weeks, then attempt to increase again once symptoms are controlled.
Will switching to Ozempic (lower dose semaglutide) help with diarrhea?
Possibly. Ozempic maxes out at 2.0mg weekly vs Wegovy's 2.4mg, so the slightly lower dose may cause fewer GI side effects. However, you'll also get less weight loss benefit. Some people also switch to tirzepatide (Mounjaro/Zepbound), which works differently and may cause less diarrhea for some individuals (though constipation is more common with tirzepatide).
Can probiotics prevent diarrhea on Wegovy?
Evidence is limited, but some people report improvement with specific strains like Saccharomyces boulardii or Lactobacillus rhamnosus GG. Probiotics are unlikely to prevent diarrhea entirely, but they may reduce severity. Give them 3-4 weeks to work. Look for high-quality, multi-strain formulas with 10+ billion CFUs.
Is it normal to alternate between diarrhea and constipation on Wegovy?
Yes, very common. GLP-1 medications disrupt normal bowel patterns, and your gut is trying to find a new rhythm. You may have diarrhea for a few days, then constipation for a few days. This usually stabilizes over time. Using Metamucil (soluble fiber) can help regulate both—it absorbs water during diarrhea and softens stool during constipation.
The Bottom Line
Diarrhea on Wegovy is common (8-15% of users) but usually improves within 4-8 weeks as your digestive system adapts to the medication.
Most effective management strategies:
- Follow a low-fat, low-fiber diet during active diarrhea
- Use Imodium as needed (2mg after first loose stool, safe for daily use)
- Stay aggressively hydrated with electrolyte drinks
- Avoid trigger foods: high-fat meals, sugar alcohols, excess caffeine
- Consider cholestyramine if you have bile acid diarrhea (yellow/green, urgent)
When to seek medical attention:
- Severe dehydration (dizziness, dark urine, confusion)
- Blood in stool or black, tarry stools
- High fever with diarrhea
- Diarrhea lasting >2 weeks despite treatment
Work with a medical provider who can help you adjust your diet, recommend appropriate medications, and modify your dose if needed. Most people can successfully manage diarrhea and continue losing weight on Wegovy.