A combination of symptoms, vomiting and diarrhoea indicates the presence of many causes. Although uncomfortable and inconvenient, these are key symptoms that ensure the elimination of pathogens from the gastrointestinal tract. Common initiating factors include infections, abdominal pain, food intolerance, stress, and certain drugs.
The 6 Main Causes of Vomiting and Diarrhoea
1. Infections
Viral Gastroenteritis (Stomach Flu): One of the most common causes, spread through contaminated food, water, or direct contact.
Bacterial Food Poisoning: Bacteria like Salmonella and E. coli can cause severe vomiting, diarrhoea, stomach cramps and fever.
Parasitic Infections: Parasites such as Giardia cause diarrhoea and vomiting, especially from infected water.
2. Food Intolerances and Allergies
Lactose Intolerance: Inability to break down lactose can cause bloating, diarrhoea and vomiting after dairy.
Coeliac Disease: An autoimmune disease in which gluten consumption causes damage to the small intestine.
Food Allergies: Allergens like shellfish and peanuts can trigger severe reactions including vomiting and diarrhoea.
3. Medication Side Effects
Some medicines — including antibiotics, painkillers and chemotherapy — can trigger nausea, vomiting and diarrhoea as side effects.
4. Stress and Anxiety
Stress and anxiety can manifest physically as vomiting and diarrhoea — sometimes referred to as a "nervous stomach" or stress-related gastrointestinal response.
5. Pregnancy
Nausea and vomiting (morning sickness) are common in early pregnancy. Hormonal changes, dietary adjustments and prenatal vitamins may also cause diarrhoea.
6. Chronic Conditions
Irritable Bowel Syndrome (IBS): A disorder of the large intestine causing chronic diarrhoea, bloating and abdominal pain, often triggered by stress or certain foods.
Inflammatory Bowel Disease (IBD): Including Crohn's disease and ulcerative colitis — causes chronic diarrhoea, vomiting, weight loss and severe abdominal pain.
Supporting long-term gut health
If IBS or recurring digestive issues are affecting you, increasing daily dietary fibre with a psyllium husk supplement can support bowel regularity and long-term gut health. Roisin Cahill MPSI, pharmacist at Chemco and Irish distributor of SylliFlor, has recommended it to thousands of patients for IBS, constipation and gut health. Learn more about SylliFlor psyllium husks →
Vitamins that Help with Nausea and Diarrhoea
1. Vitamin C
Vitamin C is an antioxidant that supports the immune system and reduces inflammation. It helps reinforce the body's defences against infection during episodes of vomiting or diarrhoea.
2. Vitamin B6
Vitamin B6 is classically used for nausea and vomiting, particularly in pregnancy. It affects neurotransmitters in the brain that regulate nausea.
3. Vitamin A
Diarrhoea can deplete vitamin A, which is required for maintaining healthy mucosal surfaces in the gastrointestinal tract. Replacement supports healing and regeneration of the gut lining.
4. Electrolytes
While not a vitamin, electrolytes — including sodium, potassium and magnesium — are essential to replace after fluid loss through vomiting and diarrhoea.
Common Treatments for Vomiting and Diarrhoea
1. Hydration
Hydration is the most important first step. Use water, clear broths or oral rehydration solutions to replace lost fluids and electrolytes. Sip slowly and avoid caffeinated or sugary drinks.
2. Medications
Antidiarrhoeal agents such as loperamide (Imodium) can reduce bowel movement frequency. Anti-emetics may help control vomiting and nausea. These should be used with caution if the cause is infection.
3. Probiotics
Probiotics are live bacteria that help restore gut flora balance. When the microbiome is disrupted by illness, probiotics can help shorten episodes of diarrhoea and support recovery.
Home Remedies
1. Ginger
Ginger has well-recognised antiemetic properties. It can be taken as ginger tea, capsules or candied ginger to calm the stomach and reduce nausea.
2. BRAT Diet
Bananas, Rice, Applesauce and Toast — bland, easy-to-digest foods that firm up stool and provide energy with minimal stomach irritation.
3. Peppermint
Peppermint relaxes muscles in the stomach and intestines, reducing nausea and indigestion. Available as peppermint tea or oil capsules.
4. Chamomile Tea
Chamomile calms stomach muscles and has mild anti-inflammatory properties that can benefit the digestive system.
When to Get Medical Care
Seek medical care if:
- Symptoms last more than 48 hours
- Blood in vomit or stool
- Signs of severe dehydration (dry mouth, no urine, dizziness)
- High fever with vomiting or diarrhoea
- Underlying condition such as IBS or IBD
Conclusion
Vomiting and diarrhoea are usually temporary and resolve with proper hydration and rest. For those dealing with recurring digestive issues such as IBS or bowel irregularity, supporting gut health with a daily fibre supplement like SylliFlor psyllium husks — recommended by our pharmacist Roisin Cahill MPSI — can make a meaningful long-term difference. Speak with one of our Chemco pharmacists for personalised advice.
The information provided in this blog is based on thorough research and is intended for educational purposes only. Always consult a qualified healthcare professional before using any products or following the advice mentioned here, especially if you have underlying health conditions or are on medication.