8 IBS Symptoms You Need To Know About
By Joe Leech, Dietitian (MSc Nutrition & Dietetics)
Last Updated: 25th March, 2025
Do certain foods give you embarrassing digestive trouble?
Do you race to the toilet multiple times a day, or go days without a bowel movement?
This article examines the most common symptoms of Irritable Bowel Syndrome (IBS) and what to do next.
Note that each section in this article has a ‘summary’ box (like this one) for those who want to skim the article faster. Below this is a blue contents box to show you what topics are covered in this article.
Contents
What is IBS?
① Recurrent Bloating
② Recurrent Diarrhea Is One of the Most Common IBS Symptoms
③ Long-Term Constipation
④ Alternating Constipation and Diarrhea
⑤ Abdominal Pain, Cramping and Excessive Gas
⑥ Mucus in Your Stools
⑦ Garlic and Onion Cause You Grief
⑧ Lethargy and Daytime Fatigue
What To Do If You Have IBS or FODMAP symptoms
④ Alternating Constipation and Diarrhea
⑤ Abdominal Pain, Cramping and Excessive Gas
⑥ Mucus in Your Stools
⑦ Garlic and Onion Cause You Grief
⑧ Lethargy and Daytime Fatigue
What To Do If You Have IBS or FODMAP symptoms
What is IBS?
Summary: IBS is a gastrointestinal disorder characterized by a variety of recurrent digestive symptoms. Your doctor will use these symptoms to help diagnose IBS.
1. Recurrent Bloating
Do you suffer from bloating on a regular basis?
Stomach bloating is one of the most common IBS symptoms.
In fact, up to 96% of people with IBS experience bloating because they tend to have an over-sensitive gut lining (4).
One study of 198 IBS patients found bloating to be more common among those with intermittent symptoms and diarrhea.
Summary: It seems bloating is common in both of the main IBS types, IBS-C and IBS-D.
2. Recurrent Diarrhea Is One of the Most Common IBS Symptoms
One of the most common subtypes of IBS is IBS-D.
This is usually diagnosed when diarrhea affects you every day. At least much more so than regular bowel movements or constipation.
So you may be experiencing recurrent loose or watery bowel movements, typically with increased frequency and/or urgency. And this does not just go on for day, but for weeks or months.
Approximately 40% of people with IBS have IBS-D (7).
Summary: IBS-D is a common form of IBS characterized by chronic diarrhea.
3. Long-Term Constipation
In contrast to diarrhea, long-term constipation can also be a sign of IBS.
This is known as IBS-C.
Constipation is defined as having to strain to pass bowel movements, having the sensation of incomplete evacuation, and/or struggling to pass a bowel movement regularly (8).
Roughly 35% of IBS sufferers identify with the subtype IBS-C (7).
Summary: Long-term constipation is one symptom associated with IBS.
4. Alternating Constipation and Diarrhea
Having both diarrhea and constipation is also common in IBS.
It’s called IBS-M (M is for mixed).
This is a useful chart for identifying which classification you may fall into.
See your doctor to determine what subtype you may have.
Summary: Alternating between constipation and diarrhea is common with IBS and called IBS-M.
Want more information on how to start a low FODMAP diet for IBS?
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5. Abdominal Pain, Cramping and Excessive Gas
Intestinal gas is one of the most frequent IBS symptoms.
Study participants have said they experience at least some gas 74% of the time, and excessive gas for the remainder (9).
Gas regularly accompanies abdominal pain and cramping in IBS.
The pain is often described as crampy, sharp, dull, gas-like, or a generalized ache with periods of cramps. This usually subsides after a bowel movement or passing gas.
Summary: Chronic gas accompanied with abdominal pain, cramping, and sometimes nausea, is very common with IBS and tends to ease after a bowel movement.
6. Mucus in Your Stools
Mucus in your stool is a notable symptom of IBS.
It will typically be clear or white in color.
Several other more serious digestive disorders are associated with mucus in the stool, including:
● Celiac disease
● Crohn’s disease
● Lactose intolerance
● Ulcerative colitis
● Crohn’s disease
● Lactose intolerance
● Ulcerative colitis
It’s very important that your doctor rules out any other conditions before dismissing this symptom.
Summary: Mucus in your stool can indicate other more serious issues. Alert your doctor if you have this symptom to rule out other conditions.
7. Garlic and Onion Cause You Grief
Digestive troubles after eating garlic and onion is common, especially in people with IBS.
This is because they’re very high in FODMAPs, particularly fructans. In fact, many of the symptoms in this article are often referred to as FODMAP symptoms.
Unfortunately it’s hard to avoid garlic and onion as they’re used in so many dishes and food products.
In fact, it’s likely garlic or onion powder is an ingredient in something you eat on a regular basis.
Summary: Fructans in garlic and onion can cause digestive distress for those with IBS.
8. Lethargy and Daytime Fatigue
Unexpected signs of IBS include sleep disturbances and daytime fatigue.
Sleep disturbances are a common occurrence, with one study revealing 62% of IBS sufferers had poor sleep quality (9).
The most common manifestations include:
● Sleeping less
● Waking up during sleep
● Difficulty falling asleep
● And non-restorative sleep (10).
All of these can result in daytime fatigue, which occur irrespective of other sleep-affecting conditions such as anxiety or depression (11).
Summary: Many people with IBS experience sleep disturbances and daytime fatigue.
What To Do If You Have IBS or FODMAP symptoms
If you have any of the symptoms above, go to your doctor for a check-up.
While IBS is not life-threatening, the symptoms can relate to other more serious conditions.
Once IBS is diagnosed, a dietitian can guide you on diet and lifestyle changes that will help get rid of symptoms.
A Low FODMAP Diet Can Help
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The “What Can I Eat on a FODMAP Diet?” food list
Join Expert Insights: Gut Edition — our free and trusted digestive health email newsletter — and get instant access to the complete Low FODMAP food list. (It’s free!)
Inside, you’ll find:
- A comprehensive list of what to eat — and what to avoid — on the low FODMAP diet
- Built from the latest FODMAP research, so you can trust the guidance
- Delivered straight to your inbox the moment you join
As part of Expert Insights: Gut Edition, you’ll also receive ongoing expert tips, myth-busting insights, and practical strategies to help you manage IBS and improve your gut health with clarity and confidence. Unsubscribe anytime with one click.
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