Stomach Flu vs. Food Poisoning: What's the Difference

Written By: Dr. Emma Warner

Stomach flu and food poisoning are both conditions that can cause gastrointestinal symptoms such as vomiting, diarrhea, and abdominal pain. While these two conditions share many similarities, they have some significant differences. This blog post will explore the causes, symptoms, diagnosis, treatment, and prevention of stomach flu and food poisoning and discuss how they differ. 

Stomach Flu vs. Food Poisoning: The Differences

Stomach flu and food poisoning are relatively common conditions characterised by gastrointestinal symptoms such as vomiting, diarrhoea, and abdominal pain. However, they have different causes, and understanding these differences is essential for proper treatment and prevention.   

Stomach flu, also known as viral gastroenteritis, is caused by a virus that infects the stomach and intestines. On the other hand, food poisoning is caused by eating food contaminated with harmful bacteria, viruses, or toxins. Both conditions can range in severity from mild to severe. While most patients can be treated at home, some patients may require supportive treatment in hospital, particularly at extremes of age or if they have other medical conditions.  

More About Stomach Flu

Stomach flu or viral gastroenteritis is a highly contagious condition that spreads easily through contaminated food or water or close contact with infected individuals. The common viruses that cause stomach flu include norovirus, rotavirus, and adenovirus. Stomach flu symptoms usually appear within one to three days after exposure and can last for up to 10 days (about one and a half weeks). 

The symptoms of stomach flu include: 

• Nausea and vomiting 
• Diarrhea 
• Abdominal cramps and pain 
• Fever 
• Headache 
• Muscle aches 

Most people who contract stomach flu recover without medical treatment but may need self-care measures to relieve their symptoms. These measures include:   

• Getting plenty of rest 
• Drinking fluids to prevent dehydration 
• Eating bland foods
• Avoiding alcohol and caffeine 
• Taking over-the-counter medications to relieve nausea and diarrhoea  

In severe cases, hospitalization may be necessary to replace lost fluids and electrolytes. 

Stomach Flu: What to Eat

When dealing with stomach flu, starting with fluids to prevent dehydration and slowly introducing solid foods as your stomach settles is best. Begin with clear broths or herbal teas to help hydrate and relieve nausea. A homemade oral rehydration solution consisting of 6-8 level teaspoons of sugar and ½ level teaspoon of salt dissolved in 1 litre of potable water is also effective. Once you are ready for solids, stick to the "BRAT" diet—Bananas, Rice, Applesauce, and Toast. These foods are gentle on the stomach due to their low fibre and bland nature. You can also try adding plain crackers and steamed chicken without adding fats, spices/seasoning. These foods help replenish energy without overworking your digestive system.

How Long Does Stomach Flu Last?

Stomach flu, or viral gastroenteritis, typically lasts between one and ten days, with symptoms usually resolving independently. The duration can vary depending on the specific virus causing the infection. Norovirus, one of the most common causes, often lasts one to three days. Meanwhile, rotavirus, more common in children, can cause symptoms for up to a week. During this time, it's crucial to maintain good personal hygiene, hydration and rest. While most people recover without medical intervention, persistent or severe symptoms might require a visit to a healthcare provider.

More About Food Poisoning 

Food poisoning is a condition that occurs when you consume food or water contaminated with harmful bacteria, viruses, or toxins. The most common bacteria that cause food poisoning include Salmonella, E. coli, and Listeria. The symptoms of food poisoning usually appear within a few hours to a few days after exposure and can last for up to a week. 

The food poisoning symptoms:

• Nausea and vomiting 
• Diarrhea 
• Abdominal cramps and pain 
• Fever 
• Chills 
• Headache 

The treatment of food poisoning depends on the severity and type of infection. In mild cases, self-care measures such as rest, hydration with bottled mineral or cooled boiled water, and eating plain, carbohydrate-based foods as tolerated may help you recover. Antibiotics may sometimes be necessary to treat the underlying bacterial infection.  

A note on keeping hydrated:  

The most common cause of complications from these illnesses is the resulting dehydration. In most cases, for both food poisoning and stomach flu, oral rehydration salts can be really helpful. These can be bought over the counter and made following the packet instructions, ideally with bottled mineral or cooled boiled tap water.  

These rehydration sachet packets contain salts (electrolytes) which are important for many functions in the body. When losing a lot of fluid from the body through diarrhoea and vomiting, you can also lose many of these salts, so these must be replaced to avoid complications from electrolyte imbalances. There are formulations available for both adults and children and it is important to follow the dosage instructions on the packet and to sip them slowly, as drinking them too fast can sometimes make you feel nauseated. 

Food Poisoning: What to Eat

In the case of food poisoning, the initial focus should be on clear liquids like water, clear sodas, and non-caffeinated sports drinks to combat dehydration. The use of medical-grade oral rehydration solution is advised for better consistency of electrolyte content. After managing liquids, introduce solids that are easy on the stomach but slightly more substantial than those recommended for stomach flu. Suitable options include boiled potatoes, rice porridge, and plain yoghurt, which can help restore beneficial bacteria in your gut. Avoid dairy products, except for yoghurt, and spicy and fatty foods until your recovery is more advanced. Once symptoms improve, gradually reintroduce your regular diet, but start with cooked vegetables and lean proteins to ensure easier digestion.

How Long Does Food Poisoning Last?

Food poisoning durations vary based on the contaminant involved. Symptoms can appear as soon as one hour after consumption of contaminated food and beverage or may manifest for several weeks. Most commonly, symptoms last from a few hours to several days. For instance, food poisoning from common bacteria like Staphylococcus, Salmonella or E. coli typically resolves within a week. However, some types of food poisoning, such as those caused by parasites or certain toxins, can last longer and may require medical treatment to manage the symptoms effectively. Recovery times also depend on the individual's general health and the promptness of supportive care like hydration and elimination of toxins and/or pathogens from the GI tract.

Prevention 

• Wash your hands thoroughly with soap and water before preparing or eating food, using the bathroom, and changing diapers.  
• Close the toilet lid when you flush the toilet and avoid sharing a bathroom with someone with symptoms if at all possible. 
• Cook food to the appropriate temperature to kill harmful bacteria
• Store food at the proper temperature to prevent bacterial growth
• Avoid eating undercooked or raw meat, poultry, and seafood
• Avoid eating food left out at room temperature for over two hours
• Use separate cutting boards and utensils for raw and cooked foods
• Drink only bottled or treated water when travelling to areas with poor sanitation... and this includes the water you use to brush your teeth!
  
  If you are unsure whether food has gone bad, be aware that just because it does not smell bad does not necessarily mean it is safe. If in doubt, throw it out!  

Can Probiotics help with recovering Stomach Flu and Food Poisoning?  

What are probiotics? 

Probiotics are live microorganisms commonly found in foods like live yogurt and fermented foods and are also available in supplement form. There is increasing interest in how probiotics can support and optimise our gut health. 

Can probiotics help with recovery?

In stomach flu or food poisoning, there is generally no strong evidence to suggest that they will help shorten the duration of symptoms. However if this is something you would like to know more about, it is worth discussing with your doctor, as there are certain circumstances where certain probiotics may potentially help with feeling yourself again after stomach upset. They can discuss your individual circumstances and recommend the appropriate strain of probiotic that might be best to try. 

If you are experiencing stomach flu or food poisoning symptoms, staying hydrated and rest as much as possible is the most important thing. Once you feel you can eat normally again, it is probably a good idea to consider incorporating probiotic-rich foods into your diet to help support your digestive health and, as above, feel free to discuss probiotics with your doctor if you would like to.  

Stomach flu and food poisoning are both conditions that can cause gastrointestinal symptoms such as vomiting, diarrhoea, and abdominal pain. While they share some similarities, they have different causes, and understanding these differences is essential for proper treatment and prevention. The symptoms can be quite uncomfortable and can last for several days.   

Good hygiene habits and safe food handling practices can reduce your risk of contracting these conditions and protect your health.  

If you experience severe or prolonged symptoms, are struggling to keep fluids, or you or your child are tired or confused, seek medical help immediately.   

References

(1) Mayo Clinic.Viral gastroenteritis (stomach flu). Retrieved June 16, 2023, from https://www.mayoclinic.org/diseases-conditions/viral-gastroenteritis/symptoms-causes/syc-20378847 

(2) Centre for Health Protection. Food Poisoning. Retrieved June 16, 2023, from https://www.chp.gov.hk/en/healthtopics/content/24/43.html 

(3) Cleveland Clinic. Stomach Flu (Gastroenteritis). Retrieved June 17, 2023, from https://my.clevelandclinic.org/health/diseases/12418-gastroenteritis 

(4) NHS. Food Poisoning. Retrieved June 17, 2023, from https://www.nhs.uk/conditions/food-poisoning/ 

(5) Probiotic Professionals. Probiotics for Upset Stomach and Food Poisoning. Retrieved June 17, 2023, from https://www.optibacprobiotics.com/professionals/latest-research/gut-health/probiotics-for-diarrhea