Flu-related diarrhea typically resolves on its own within one to three days, but you can speed recovery and reduce discomfort with the right fluids, foods, and over-the-counter options. The key priorities are preventing dehydration, easing your gut back to normal, and knowing when the situation needs medical attention.
Before diving into remedies, it helps to know which “flu” you’re actually dealing with, because that affects what works best.
Respiratory Flu vs. Stomach Flu
These are two different illnesses that people often lump together. Influenza is a respiratory virus that attacks the nose, throat, and lungs. It can cause diarrhea as a side effect, particularly in children, though researchers still don’t fully understand why a respiratory virus triggers gut symptoms. Gastroenteritis, commonly called “stomach flu,” is caused by entirely different viruses (usually norovirus or rotavirus) that directly infect the intestines, producing watery diarrhea, nausea, vomiting, stomach cramps, and sometimes a low-grade fever.
The good news: the approach to managing diarrhea is largely the same regardless of which virus is causing it. The steps below apply to both.
Replace Fluids Before Anything Else
Diarrhea drains water and electrolytes fast, especially when you’re also sweating from a fever. Dehydration is the main danger of flu diarrhea, not the diarrhea itself. Your first priority is replacing what you’re losing.
Oral rehydration solutions (sold as Pedialyte or store-brand equivalents) are the gold standard because they contain the right balance of sodium, potassium, and glucose to help your intestines absorb water efficiently. For adults, clear broths, diluted fruit juice, and coconut water also work. Sip small amounts frequently rather than gulping large volumes, which can trigger more nausea. Avoid alcohol, full-strength fruit juice, caffeinated drinks, and sugary sodas, all of which can pull more water into the intestines and make diarrhea worse.
For children, oral rehydration solution is especially important. Kids under five can become dangerously dehydrated within hours.
What to Eat (and When)
You’ve probably heard of the BRAT diet: bananas, rice, applesauce, and toast. It’s a reasonable starting point for the first day or two, but there’s no research showing it works better than other bland foods, and sticking to only those four items can leave you short on protein and nutrients right when your body needs them for recovery.
Better options include brothy soups, oatmeal, boiled potatoes, crackers, and unsweetened dry cereals. These are all gentle on the stomach while providing more variety. Once you can keep food down comfortably, start adding cooked carrots, sweet potatoes without skin, avocado, skinless chicken or turkey, fish, and eggs. These foods are bland enough to tolerate but deliver the protein and micronutrients that help you heal faster.
Avoid dairy, fried or greasy foods, high-fiber raw vegetables, and spicy meals until your stools return to normal. Fatty and high-fiber foods speed gut motility, which is the opposite of what you want right now.
Over-the-Counter Medications
Loperamide (the active ingredient in Imodium) slows intestinal contractions, giving your gut more time to absorb water. It can reduce the frequency of loose stools and is available without a prescription. Follow the package directions carefully and don’t exceed the recommended dose. If your diarrhea hasn’t improved after two days of use, or you develop a fever, stop taking it and contact a healthcare provider. Loperamide should not be used in children under two years old or in anyone with bloody stool, severe abdominal pain without diarrhea, or a known bacterial gut infection.
Bismuth subsalicylate (the active ingredient in Pepto-Bismol) is another option. It coats the stomach lining and has mild anti-inflammatory properties in the gut. It can help with both diarrhea and nausea. However, it contains a salicylate (related to aspirin), so it should be avoided in children and teenagers recovering from a viral illness due to the rare but serious risk of Reye’s syndrome. Adults taking blood thinners or aspirin should also check with a pharmacist first.
Probiotics Can Shorten Recovery
Adding a probiotic alongside oral rehydration has solid evidence behind it. Studies show probiotics reduce the duration of acute infectious diarrhea by about 25 hours on average and cut the risk of diarrhea lasting more than four days by nearly 60%. They also reduce stool frequency by the second day of use.
Strains with the most evidence include Lactobacillus rhamnosus GG and Saccharomyces boulardii, but research suggests the specific strain matters less than simply taking one. Low-dose and high-dose preparations appear similarly effective. A course of 5 to 10 days is the typical recommendation. You can find these in capsule form at most pharmacies, or in fermented foods like yogurt with live cultures (though dairy may not sit well until your gut calms down, so capsules are often easier to tolerate).
Soothing Drinks That May Help
Ginger tea is one of the more evidence-backed home remedies for nausea and digestive discomfort. A 2023 study found that ginger root supplementation improved gut microbiome diversity and eased indigestion symptoms. You can make it simply by simmering sliced fresh ginger root in hot water for 10 to 15 minutes. Chamomile tea is another gentle option that many people find calming for the stomach, though the evidence for it specifically reducing diarrhea is more limited.
Both are worth trying as part of your fluid intake. They’re warm, hydrating, and unlikely to cause any harm.
Zinc for Children
The World Health Organization recommends zinc supplementation for children with diarrhea: 20 mg per day for 10 to 14 days, or 10 mg per day for infants under six months. Zinc helps reduce the severity and duration of diarrheal episodes and lowers the chance of recurrence in the following weeks. This recommendation is primarily aimed at children in settings where zinc deficiency is common, but it’s a safe and inexpensive addition worth discussing with your pediatrician.
Signs That Need Medical Attention
Most flu diarrhea clears up within a few days. But certain signs point to dehydration or a more serious problem that requires professional care. Seek help if you or your child experiences any of the following:
- Diarrhea lasting more than 24 hours (especially in children or older adults)
- Inability to keep fluids down
- Bloody or black stool
- Fever of 102°F (39°C) or higher
- Unusual confusion, irritability, or sleepiness
In young children, watch for dry mouth, no tears when crying, fewer wet diapers than usual, and sunken eyes. These are reliable early signs of dehydration that warrant a call to your pediatrician or a trip to urgent care rather than waiting it out at home.