Nausea may be caused by medical conditions that often overlap with IBS, such as functional dyspepsia (DP) or gastroesophageal reflux disease (GERD). Several rarer medical conditions such as ulcerative colitis, Crohn’s disease, and migraine headaches may also cause nausea. (3)
Why does IBS cause nausea?
Irritable bowel syndrome is a complex disorder that is not fully understood. However, a couple of theories explain how IBS may be the cause of nausea. Acid reflux is commonly experienced in people with IBS and may cause nausea as stomach acid travels the wrong way up the esophagus. (4) Alternatively, feelings of stress and anxiety over the unpleasant symptoms of irritable bowel syndrome – such as bloating, cramping, and diarrhea – may cause nausea. This is part of the ‘biopsychosocial model’ explaining the link between mental and physical phenomena. (5)
What other conditions may cause nausea?
IBS typically causes pain and bloating, and nausea occurring with IBS may be caused by other medical conditions that overlap with IBS. These include:
• Functional dyspepsia (FD)
• Gastroesophageal reflux disease (GERD)
• Migraine headache
• Crohn’s disease
• Ulcerative colitis (4, 6, 7, 8)
What is functional dyspepsia?
Functional dyspepsia (FD) also known as ‘indigestion’ describes a group of symptoms affecting the gastrointestinal system. One in three people with FD also have IBS. (9) Symptoms of FD include nausea and are diagnosed in the absence of any obvious physical cause, such as acid reflux or ulcers. The most common symptoms of FD include:
• Abdominal bloating
• Pain in abdomen after eating
• Rapidly feeling full
• Belching (10)
The precise cause of FD is not known, however, several factors may trigger FD or worsen symptoms These include:
• Stress and anxiety
• Infection with the bacteria, helicobacter pylori (11)
Diagnosis of FD involves ruling out other conditions such as stomach cancer and gallstones using gastroscopy or colonoscopy. Treatment options for FD include:
• Medication to reduce acid in the stomach, such as antacids and proton pump inhibitors
• Antibiotics helicobacter pylori infection is present (12)
There is currently no cure for FD. Lifestyle factors such as limiting alcohol and tobacco, reducing stress, losing weight and avoiding ‘trigger’ foods may also help relieve symptoms. (13)
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What is GERD?
Gastroesophageal reflux disease (GERD) is a GI condition in which stomach acid flows back up the esophagus. The overlap with IBS is strong as up to 79% of those with IBS have experienced GERD. (14) The acid reflux in GERD can irritate the lining of the esophagus and cause nausea and is caused by sphincter muscles connecting the stomach to esophagus failing to properly contract. Common symptoms of GERD include:
• Heartburn (pain in the chest)
• Difficulty swallowing
• Regurgitation of food
• The sensation of a lump in the throat (15)
Diagnosis of GERD may involve upper endoscopy, to rule out inflammation or other conditions, or an ambulatory acid (pH) probe test, to test how much stomach acid is regurgitated. GERD may be treated by over-the-counter and prescription medications such as:
• Antacids, to neutralize stomach acid
• H2 receptor blockers, reducing acid production
• Proton pump inhibitors (PPIs), to block acid production
• Surgery may be required to strengthen the ring of muscles of the oesophageal sphincter. (16)
Lifestyle changes that may improve GERD involve avoiding certain ‘trigger’ foods, such as:
• Acidic foods
• Fatty foods
• Alcohol (17)
What are migraine headaches?
Migraines are severe headaches typically felt on one side of the head. Up to 53% of people with IBS report migraines and 9 out of 10 people who get headaches experience nausea. (6, 18) Other common symptoms of migraine headaches include:
• Sensitivity to light
• Speech difficulty
• Motor disturbances
• Visual disturbances (aura) (19)
The cause of migraines are not known, although they are believed to be related to changes to nerves and blood vessels in the brain. Migraines are common, affecting more than to 1 in 10 individuals. (20)
Alternative headaches that may cause nausea include:
• Brain aneurysm
• Brain injury
• Brain tumor
• Cluster headaches (21)
Migraines are treated with painkillers such as paracetamol or ibuprofen. For migraines causing nausea, anti-emetic medication may be prescribed. Treating a migraine headache may help to relieve symptoms of nausea in patients with IBS. (22)
What is ulcerative colitis?
Ulcerative colitis is a chronic (long-term) gastrointestinal condition in which the colon becomes inflamed. Many symptoms of ulcerative colitis overlap with IBS. This has led some experts believe IBS is actually an early form of ulcerative colitis. (23) Common symptoms of ulcerative colitis include:
• Abdominal pain
• Swelling of joints
• Irritation of eyes
• Mouth ulcers (24)
Ulcerative colitis symptoms often follow a pattern of flare-ups and remission. It differs from IBS in that other parts of the body are affected. Medication treatment for ulcerative colitis involves corticosteroids, immunosuppressants or a new class of drugs acting on the immune system, biologics. Dietary changes such as eating smaller meals during the day, increasing fluid intake and avoiding high-fiber foods may also prevent flare-ups of ulcerative colitis. These treatments may help to reduce nausea in Crohn’s disease and other symptoms. (25, 26)
What is Crohn’s disease?
Crohn’s disease is an inflammatory bowel disease like ulcerative colitis. However, Crohn’s disease may affect any part of the gastrointestinal tract and most commonly the colon or the ileum (lower part of small intestine). Like ulcerative colitis, Crohn’s disease may represent a more advanced form of IBS, according to some experts (27). Nausea and loss of appetite are common in people with Crohn’s disease and other common symptoms include:
• Abdominal pain
• Diarrhea (28)
Crohn’s disease occurs at a similar rate to ulcerative colitis, affecting 1 in 650 people. Nausea and other symptoms of Crohn’s disease can be managed with medication treatments. These include corticosteroids, oral 5-aminosalicylates, antidiarrheals and immune system suppressors. Some of these treatments may help to resolve symptoms of nausea whereas others may worsen nausea. Hence, it is important to consult a doctor to ensure an appropriate medication is selected. (29)
Medication may cause nausea
People with IBS may also experience nausea as a side effect of IBS or non-IBS related medications. These include:
• Lubiprostone, for IBS
• Antibiotics (e.g. erythrocin)
• Anti-inflammatory drugs (e.g. ibuprofen)
• Chemotherapy drugs
• Birth control pills (30)
If you suffer from IBS and are currently taking any of the above medications, these may be responsible for nausea. Nausea is a common side effect of drugs, since most drugs have multiple effects on the body. Anti-inflammatory drugs may reduce pain but also irritate the stomach lining, causing nausea. Often, the active ingredient in a drug causes nausea. People of older age may require higher doses of medications and experience cause nausea more commonly.
What else causes nausea?
Aside from conditions overlapping with IBS and medications, there are a range of other possible causes of nausea, including:
• Gastrointestinal disorders (e.g. appendicitis, cholecystitis and pancreatic)
• Obstruction of the gastrointestinal tract
• Infections of the gastrointestinal tract (gastroenteritis)
• Psychiatric illnesses (e.g. anxiety, depression, anorexia nervosa, bulimia nervosa)
• Celiac disease (31)
Treatment of nausea
Several general guidelines may help reduce symptoms of nausea. These include:
• Avoid fried or greasy food
• Drink only clear fluids such as water, sports drink or broth
• Eat bland, light foods
• Avoid mixing hot and cold foods
• Avoid sweet food (32)
However, if nausea is related to IBS, then several IBS-specific therapies may help improve nausea. These are listed below.
The Low FODMAP diet for nausea and IBS
The low FODMAP (fermentable oligo-, di-, mono-saccharides and polyols) diet was developed for the treatment of IBS. The diet eliminates foods known to cause symptoms of IBS, such as abdominal pain and nausea. Common foods eliminated from the diet include:
• Lactose: found in milk and dairy products
• Fructose: found in table sugar and many fruits and vegetables.
• Fructans: found in grain products like rye, wheat and barley
• Polyols: used as artificial sweeteners, and found in some fruits and vegetables
• Galactans: found in legumes
The low FODMAP may provide excellent relief from nausea and other symptoms. However, it is important to consult a dietitian to ensure adequate nutrition can be maintained while following the diet. (33)
Stress management for nausea and IBS
Stress is a known risk factor for nausea, as well as IBS. Managing and treating feelings of stress and anxiety can reduce nausea and gastrointestinal symptoms. Effective stress-management strategies backed up by scientific research for IBS and stress include:
• Meditation and mindfulness
• Cognitive-behavioural therapy (CBT)
By acting on the gut-brain connection, these treatments can improve the physical symptom of nausea. (34, 35)
Probiotics for nausea and IBS
Probiotics are live bacteria similar to the gut bacteria and provide health benefits. They have been shown to improve GI function and symptoms such as nausea. One study showed that a 3-week period of taking probiotics containing Bifidobacterium longum and Lactobacillus acidophilus significantly reduced stress-related GI symptoms of pain, nausea, and vomiting. (36)
Probiotics have also been shown to improve symptoms of IBS. One study of 77 IBS patients showed improvements to symptoms with probiotics containing Lactobacillus and Bifidobacterium strains. It was suggested that benefits arose through changes to the immune system. (37)
A Word from Mindset Health
Nausea is a common symptom of IBS. Nausea may arise from IBS itself or the strong overlap between IBS and digestive diseases such as functional dyspepsia, gastroesophageal reflux disease (GERD), inflammatory bowel diseases (IBD) - Crohn's disease and ulcerative colitis. Migraine headaches are also common in IBS and may lead to nausea. Otherwise, food intolerances or other functional gastrointestinal disorders may be responsible. Healing the digestive tract and large intestine and preventing flare-ups of IBS and nausea may involve adopting the low FODMAP diet, stress management strategies such as hypnotherapy, or probiotics. These strategies may reduce stomach pain and cramping, improve bowel movements and bowel habits, and other IBS symptoms. Consulting a gastroenterologist is advisable to confirm diagnosis of IBS and subtype (IBS-C, IBS-D, IBS-M) and assess treatment options.