During an IBS flare-up, the right combination of over-the-counter remedies, dietary changes, and targeted supplements can significantly reduce pain, bloating, and irregular bowel habits within hours to days. What you reach for depends on whether your flare leans toward diarrhea, constipation, or a painful mix of both. Here’s what works and how to use it.
For Diarrhea-Dominant Flares
Loperamide (sold as Imodium) is the most effective over-the-counter option for slowing urgent, loose stools. The standard approach is to take two tablets (4 mg) after the first loose bowel movement, then one tablet (2 mg) after each subsequent one, up to a maximum of four tablets in 24 hours. It works by slowing the muscle contractions in your gut, giving your intestines more time to absorb water. Keep use to two days or fewer unless your doctor says otherwise.
If you’re dealing with looser-than-normal stools plus nausea or general stomach upset, bismuth subsalicylate (Pepto-Bismol) can help. It coats the lining of the digestive tract and reduces inflammation. It’s not as targeted as loperamide for pure diarrhea, but some people find the combination of effects more comfortable during a multi-symptom flare.
For Constipation-Dominant Flares
An osmotic laxative like polyethylene glycol 3350 (sold as MiraLAX) draws water into the colon to soften stool. The standard dose is 17 grams of powder mixed into a glass of water, taken once daily. It typically takes one to three days to produce a bowel movement, so it’s more of a same-day-or-tomorrow fix than an instant one. Unlike stimulant laxatives, it doesn’t cause the cramping that can make an already painful flare worse.
Soluble fiber supplements like psyllium husk (Metamucil) are a good longer-term addition. Soluble fiber dissolves in water and forms a soft gel that eases stool through the intestines without the irritation that insoluble fiber (bran, raw vegetable skins) can cause. If you’re not already taking fiber regularly, start with a small amount and increase gradually over a week or two. Jumping straight to a full dose during a flare can temporarily worsen bloating and gas.
For Cramping and Abdominal Pain
The pain during an IBS flare comes largely from spasms in the smooth muscle of the intestinal wall. Enteric-coated peppermint oil capsules act as a natural antispasmodic, relaxing that muscle and reducing both pain and bloating. A clinical trial using two capsules twice daily for four weeks found peppermint oil significantly more effective than placebo at reducing abdominal symptoms. Look specifically for enteric-coated versions, because the coating prevents the capsule from dissolving in your stomach (which can cause heartburn) and delivers the oil to your intestines where it’s needed.
For more intense cramping, prescription antispasmodics exist. These work by blocking nerve signals that trigger gut contractions. They’re typically started at a lower dose and increased over the first week based on how you respond. If you find that over-the-counter options aren’t touching your pain during flares, this is worth bringing up at your next appointment.
For Bloating and Gas
Simethicone (Gas-X, Phazyme) breaks up gas bubbles in the digestive tract so they’re easier to pass. It doesn’t prevent gas from forming, but it reduces that uncomfortable, distended feeling. Taking it after meals, up to three times a day, is the typical approach during a flare. It’s one of the safest over-the-counter options available since it isn’t absorbed into the bloodstream.
If you notice bloating specifically after eating beans, lentils, or certain vegetables, an enzyme supplement containing alpha-galactosidase (Beano) can help break down the specific carbohydrates that produce gas before they reach your large intestine. Take it with the first bite of a problem food for best results.
What to Eat During a Flare
Stripping your diet back to low-FODMAP foods is one of the most effective things you can do during an active flare. FODMAPs are short-chain carbohydrates that pull extra water into the intestine and ferment rapidly, producing gas, bloating, and pain. Cutting them out temporarily removes a major source of fuel for your symptoms.
Safe foods to lean on during a flare include rice, oats, potatoes, carrots, cucumber, lettuce, green beans, eggs, plain cooked chicken or fish, firm tofu, oranges, kiwifruit, blueberries, and pineapple. For dairy, stick with hard cheeses, lactose-free milk, or almond milk. Sourdough spelt bread and rice cakes are good grain options.
The foods most likely to make a flare worse include garlic, onion, mushrooms, apples, pears, watermelon, mango, wheat-based bread and pasta, cow’s milk, yogurt, ice cream, beans, lentils, cashews, and anything sweetened with honey or high-fructose corn syrup. Dried fruit is a particularly concentrated source of the sugars that trigger symptoms. Even foods that seem healthy, like asparagus and artichokes, are high in the specific carbohydrates that ferment in the gut.
You don’t need to stay low-FODMAP forever. The goal is to calm things down during the flare, then reintroduce foods one at a time to identify your personal triggers. The Monash University FODMAP app, developed by the research team that created the diet, uses a traffic-light rating system for hundreds of foods and is the most reliable guide available.
Probiotics for Longer-Term Relief
Probiotics won’t rescue you mid-flare the way loperamide or peppermint oil will, but starting the right strain can reduce the frequency and severity of future episodes. The most studied strain for IBS is Bifidobacterium infantis 35624 (sold as Alflorex or Align). In a randomized trial, this strain reduced abdominal pain, bloating, and difficulty with bowel movements significantly more than placebo over eight weeks. It also normalized markers of immune system inflammation that were elevated in IBS patients, suggesting it addresses part of the underlying biology rather than just masking symptoms.
Not all probiotics are interchangeable. Many popular products contain strains with little or no evidence for IBS specifically. When choosing a probiotic, look for the full strain designation (including the number) on the label, not just the genus and species.
Symptoms That Need Medical Attention
Most IBS flares, while miserable, resolve on their own or with the approaches above. But certain symptoms during a flare suggest something beyond IBS may be happening. These include unintentional weight loss, blood in your stool, fever, persistent vomiting, diarrhea that wakes you from sleep at night, and belly pain that has no connection to bowel movements. New onset of symptoms after age 50 also warrants evaluation, as does anemia. These are considered alarm signs because they’re not typical of IBS and can indicate inflammatory bowel disease, infection, or other conditions that need different treatment.