Diarrhea lasting a full week sits right at the boundary between what doctors consider acute (under one week) and persistent (two to four weeks). Most short-lived stomach bugs clear up in a few days, so if yours hasn’t, something beyond a simple virus is likely keeping your gut irritated. The causes range from infections that take longer to shake, to medications, dietary triggers, or a condition you haven’t connected to your symptoms yet.
Where One Week Falls on the Timeline
Acute diarrhea, the kind caused by a common stomach virus, typically resolves on its own in less than a week. Persistent diarrhea lasts between two and four weeks. Chronic diarrhea means four weeks or longer. At one week, you’re in a gray zone: long enough that the most common viral causes should have cleared, but not yet long enough to signal a chronic problem. This is the point where it’s worth looking more carefully at what might be going on.
Infections That Last Longer Than a Few Days
If your diarrhea started suddenly with cramping or nausea and simply never stopped, an infection is still the most likely explanation. Most viral stomach bugs burn out quickly, but certain bacteria and parasites are slower to clear.
Bacterial infections from organisms like Campylobacter, Salmonella, Shigella, and some strains of E. coli can cause mucosal inflammation in the intestines that keeps diarrhea going well past the first few days. These are typically picked up from contaminated food or water.
Parasites are the pathogens most commonly identified in people with persistent diarrhea. Giardia is the top suspect, especially if your stools are greasy or fatty, you’re dealing with a lot of gas, or your symptoms seem focused in the upper abdomen. Untreated giardia can cause symptoms lasting months, even in otherwise healthy people. Cryptosporidium is another increasingly common cause, and Cyclospora (often linked to contaminated produce) has become more frequently recognized in recent years. If you’ve traveled internationally in the weeks before symptoms started, the list of possible parasites expands further.
One infection worth special attention: C. difficile. If you’ve taken antibiotics recently, including for an unrelated issue, the antibiotics can wipe out protective gut bacteria and allow C. difficile to take over. This produces a persistent, watery diarrhea that won’t improve with more antibiotics and often gets worse with them.
Medications That Trigger Ongoing Diarrhea
Nearly any medication can cause diarrhea as a side effect, but some are much more likely culprits than others. If your week of diarrhea lines up with starting or changing a medication, that connection is worth investigating.
- Antibiotics are one of the most common causes, disrupting normal gut bacteria even while treating an infection elsewhere in the body.
- Metformin, widely prescribed for type 2 diabetes, causes diarrhea in a significant percentage of users, especially early on or after a dose increase.
- Magnesium-containing antacids draw water into the intestines and can produce loose stools for as long as you keep taking them.
- NSAIDs like ibuprofen and naproxen irritate the gut lining and can cause diarrhea with regular use.
- Proton pump inhibitors used for heartburn or acid reflux occasionally cause diarrhea, though this is less common.
- Herbal teas and supplements containing senna or other natural laxatives can cause diarrhea that people don’t attribute to the product because they think of it as just tea.
The fix here can be straightforward: if the timing matches, talk to whoever prescribed the medication about switching or adjusting the dose. Don’t stop prescribed medications on your own, but do flag the symptom.
Dietary Causes You Might Not Suspect
Some foods cause ongoing diarrhea not because you’re “sick” but because your gut can’t fully absorb certain compounds. Sugar alcohols, found in sugar-free gum, mints, protein bars, and many “diet” or “keto” products, are a common offender. Sorbitol, xylitol, and mannitol accumulate in the colon because your body absorbs them poorly. They draw water into the intestines through osmotic pressure, producing watery diarrhea, bloating, and gas. People who chew multiple pieces of sugar-free gum daily or eat several sugar-free snacks can develop persistent symptoms without ever connecting them to the cause.
Lactose intolerance and fructose malabsorption work through similar mechanisms. If you’ve recently increased your intake of dairy, fruit juice, honey, or high-fructose foods, that shift alone could explain a week of loose stools. The diarrhea continues for as long as the trigger stays in your diet.
When a Gut Infection Leaves Lasting Effects
Sometimes diarrhea that started with a clear infection continues even after the pathogen itself is gone. This is called post-infectious IBS, and it happens because the original infection disrupts the relationship between your gut’s immune system and its microbiome. The inflammation lingers after the bug is cleared, and the result is ongoing diarrhea, cramping, or urgency that can persist for weeks or months.
Post-infectious IBS is worth considering if you had an obvious stomach bug, perhaps with vomiting or fever, that seemed to improve but left you with bowel habits that never fully returned to normal. It doesn’t mean you’re still infected. It means the infection changed how your gut functions, at least temporarily.
Signs That Need Prompt Medical Attention
A week of diarrhea on its own is worth a doctor’s visit, but certain symptoms alongside it signal something more urgent:
- Blood or black color in your stool, which can indicate bleeding somewhere in the digestive tract.
- Fever above 101°F (38.3°C), suggesting your body is fighting an active infection.
- Severe abdominal or rectal pain beyond ordinary cramping.
- Signs of dehydration: excessive thirst, dark urine, dizziness, dry mouth, very little urination, or feeling faint when standing up.
Dehydration is the most immediate physical risk from prolonged diarrhea. Your body loses water and electrolytes with every loose stool, and after a week, those losses add up. If you’re feeling weak, lightheaded, or your urine is dark, you need to aggressively replace fluids and electrolytes, and see a doctor soon.
What Happens at the Doctor’s Office
For diarrhea lasting this long, your doctor will likely want a stool sample. The standard approach now is a PCR-based panel that tests a single stool specimen for a wide range of bacteria, viruses, and parasites all at once. This is faster and more comprehensive than older methods that required separate cultures for each suspected organism. Results typically come back within a day or two.
Your doctor will also ask about recent travel, antibiotic use, new medications, and dietary changes. These details narrow the possibilities significantly. If the stool panel comes back negative, the investigation may shift toward food intolerances, medication effects, or conditions like IBS or inflammatory bowel disease, depending on your overall picture.
In the meantime, staying hydrated is the single most important thing you can do. Water helps, but oral rehydration solutions or broths that contain sodium and potassium replace what diarrhea actually drains from your body. Avoid caffeine, alcohol, and large amounts of sugar or fruit juice, all of which can worsen loose stools.