Why Do My Farts Smell So Bad? 7 Potential Causes and Treatments (2025)

The average person passes gas up to 20 times a day; farting is a normal part of the digestive process. However, certain factors can make you produce extra-smelly farts, such as the foods you eat, constipation, or food intolerances. Whether the smell resembles rotten eggs or another pungent odor, having smellier-than-usual farts can be embarrassing but usually isn't harmful.

1. High-Fiber Foods

Certain high-fiber foods can cause you to have smelly farts. Examples of such foods include:

• Asparagus
• Beans
• Broccoli
• Cabbage
• Cauliflower
• Legumes (e.g., lentils, peas, chickpeas)
• Whole grains

These foods contain insoluble fiber (fiber that can't dissolve in water). Unlike soluble fiber, which dissolves in water and is absorbed by the body, insoluble fiber engages the body's gut microbiome to digest it through fermentation, resulting in gas.

Some foods, such as legumes, beans, cabbage, Brussels sprouts, and asparagus, contain raffinose, a complex sugar your body can't digest, resulting in additional gas production.

2. Food Intolerances

A food intolerance is an adverse reaction to a specific type of food, usually caused by an inability or limited ability to digest or absorb certain foods or their components. Some of the most common food intolerances that result in gas and other gastrointestinal (GI) issues include:

• Lactose intolerance: People with lactose intolerance do not produce enough of the enzyme lactase, which helps digest lactose (the sugar found in milk).
• Non-celiac gluten intolerance: People with non-celiac gluten intolerance have problems digesting gluten, a protein in grains.
• Fructose intolerance: People with fructose intolerance lack the protein necessary to break down fructose, a sugar compound found naturally in fruits and vegetables.
• FODMAP intolerance: People with FODMAP intolerance have trouble digesting certain carbohydrates called FODMAPs, which is an acronym for fermentable oligosaccharides, disaccharides, monosaccharides, and polyols.
  

3. Constipation

Smelly farts can be a symptom of constipation—having fewer than two or three bowel movements per week.

Constipation causes stool (poop) to sit in your digestive tract for longer than usual. As long as the stool remains, bacteria in your colon work to digest sugars in your waste through fermentation, which creates gas. The longer the stool remains in your colon, the more gas you produce.

4. Medication

Certain medications can affect digestion, disrupt your gut microbiome, or promote constipation or diarrhea, resulting in smelly farts.

Examples of medications that can contribute include:

• Antacids
• Antibiotics
• Anticholinergic drugs (medicines that treat various conditions affecting the nervous system; they block the chemical messenger acetylcholine)
• Antidepressants
• Calcium channel blockers (medications to treat high blood pressure and other cardiovascular conditions)
• Chemotherapy medications
• Diarrhea medications, such as Imodium (loperamide) or Kaopectate (bismuth subsalicylate)
  
• Fiber supplements and bulking agents, such as Citrucel (methylcellulose fiber) and Metamucil (psyllium fiber)
• Iron pills
• Laxatives
• Multivitamins
• Nonsteroidal anti-inflammatory drugs (NSAIDs), such as Aspirin or Advil (ibuprofen)
• Opioid pain medications
  

5. Bacteria and Digestive Tract Infections

The following types of bacteria and digestive tract infections can produce smelly farts:

• Gastroenteritis:Gastroenteritis, also known as the "stomach flu," causes inflammation of your stomach and intestines and can lead to increased gas, among other symptoms.
• Small intestinal bacterial overgrowth (SIBO): Bacteria and digestive tract infections can increase bacteria in your small intestine, causing problems such as diarrhea, unintended weight loss, and excess gas.
• Gut dysbiosis: Gut dysbiosis is an imbalance of the microorganisms in your gastrointestinal tract. It can occur from an overgrowth of harmful bacteria or inadequate beneficial bacteria in your digestive system.
  

6. Colon Cancer

Though having smelly farts is usually harmless, excessive gas may be a sign of colon cancer. Research indicates that colon cancer cells produce large amounts of hydrogen sulfide, a gas with a pungent "rotten egg" smell.

Smelly farts can also occur when a tumor from colon cancer causes a significant bowel obstruction. Depending on the size and location, the obstruction can impact your ability to pass gas and/or stool, causing a buildup of gas that becomes smelly as it remains in your colon.

7. Bariatric Surgery

After bariatric (weight loss) surgery, some people experience an increase in smelly farts due to a condition called dumping syndrome.

Abdominal cramps, diarrhea, and gas are signs of early dumping syndrome, which occurs when a dense mass of food is dumped into the small intestine at an earlier-than-normal stage of digestion.

When to Contact a Healthcare Provider

In most cases, smelly farts occur as part of your normal body function and are not a cause for concern. However, persistent smelly gas may indicate an underlying health problem or the need for dietary changes.

Contact a healthcare provider or agastroenterologist (a gastrointestinal specialist) if you have smelly farts accompanied by any of the following symptoms:

• Bloody stools
• Constipation
• Diarrhea
• Fever
• Heartburn
• Melena (black and tarry stools)
• Nausea
• Oily, foul-smelling stools
• Persistent pain in your stomach or rectum
• Symptoms that change or become more intense
• Treatments that worked are no longer effective
• Unintended weight loss

How to Treat Flatulence at Home

Natural Remedies

Natural remedies to relieve gas include:

• Anise
• Caraway
• Chamomile tea
• Coriander
• Fennel
• Peppermint tea
• Turmeric

Over-the-Counter Options

Try one of the following over-the-counter gas remedies:

• Pepto-Bismol: A medication you can take after eating to relieve abdominal pain and gas
• Beano (alpha-galactosidase): A medication you can take before eating to break down complex carbohydrates before they reach your colon
• Lactaid or Dairy Ease: A lactase enzyme you can take before eating dairy products

Tips for Preventing Smelly Farts

Depending on the cause of your smelly farts, you may be able to prevent them by following these tips:

• Add fiber-rich foods to your diet gradually: The Academy of Nutrition and Dietetics recommends increasing total fiber intake by no more than 5 grams daily until you reach your desired intake.
  
• Avoid swallowing extra air: Air swallowed through chewing gum or consuming carbonated beverages can increase gas.
• Stay hydrated: Water and other unsweetened, non-carbonated beverages help soften your stool, allowing fiber to bind and preventing it from hardening.
• Reduce foods high in sulfur: Eliminate or reduce your consumption of foods that are high in sulfur compounds that can contribute to foul-smelling farts, such as broccoli, cauliflower, cabbage, Brussels sprouts, meat, poultry, eggs, onion, and garlic.
• Treat postnasal drip: A postnasal drip can cause you to swallow more air than usual, contributing to gas.
• Increase physical activity: Research indicates that 10 to 15 minutes of minimal physical activity—like a post-meal walk—releases trapped gas better than medication.
• Manage any food intolerances: If you have a food intolerance, manage your intake of lactose, gluten, sorbitol, fructose, or other ingredients.
  

Summary

Though farting occurs as part of the natural digestive process, having excess smelly farts can be a cause for concern. In most cases, you can improve the problem by changing your diet and eating habits to limit your consumption of foods that trigger smelly farts. If lifestyle changes don't make a difference, talk to a healthcare provider to determine if you have an underlying condition contributing to smelly farts.