Maintaining the recommended levels of vitamin C is important for optimal immune function to help your body ward off colds and flu. Although both the common cold and stomach flu have initial, similar symptoms, they are caused by different viruses. Vitamin C has been shown to have some benefits against the cold virus, but these do not apply to stomach flu. However, there are things you can do to minimize your risks or shorten the length of the illness.
No clear evidence shows any direct positive effect of vitamin C on the stomach flu virus, other than its ability to boost your immune system.
What Is Stomach Flu?
Stomach flu is a general term for gastroenteritis, which is an inflammation of the gastrointestinal tract. Symptoms are often more serious and intense than the stuffy nose and sneezing you may experience from the common cold virus. The well-known norovirus is a form of stomach flu.
Are You at Risk?
Some people are more vulnerable to the infection of stomach flu. Factors that may increase your risk of developing flu or suffering from associated complications include:
- Age — young children and older adults
- Living or working in facilities with many other people, such as nursing homes or military barracks
- A weakened immune system from cancer treatments, anti-rejection drugs, corticosteroids and HIV/AIDS
- A chronic condition, such as asthma, diabetes or heart problem
- Pregnancy, particularly in the second and third trimesters
How Flu Is Spread
Stomach flu is very contagious, especially in the winter months when you might spend more time in close contact with others. You can catch stomach flu when someone who has it coughs or sneezes and sends virus-filled droplets into the air you breathe. How susceptible you are to the viral infection may be determined in part by your genes, says the Centers for Disease Control and Prevention (CDC).
Some things to avoid that might be responsible for developing stomach flu are:
- Eating food or drinking liquids that are contaminated
- Touching surfaces or objects contaminated with the virus, such as door handles, then touching your mouth, nose or eyes
- Through direct contact with someone who is infected, such as sharing food or eating utensils
Symptoms of Stomach Flu
Stomach flu often has symptoms similar to the common cold but it also targets your gastrointestinal system. You might develop symptoms 12 to 48 hours after being exposed to the virus. Some of the symptoms you could experience include:
- Fever and chills
- Headache, muscle aches
- Sore throat
- Runny or stuffy nose
- Nausea or vomiting
How Long Does Flu Last?
Symptoms can be mild to severe and get better within one to three days, but it's possible that a bout of flu can persist as long as 10 days. You may feel drained or cough for a few weeks, even after your fever and aches are gone. With a weakened immune system, complications such as pneumonia, bronchitis or sinus and ear infections may develop. Individuals with certain problems like asthma or heart failure may get sicker.
Read more: Foods to Avoid With the Stomach Virus or Flu
How Long Is Flu Contagious?
Preventing the spread of stomach flu is very difficult. If you have gastroenteritis, you are contagious for about one day before any symptoms even appear. Stomach flu is the most contagious during your illness, when symptoms such as vomiting are apparent. According to the CDC, you can still spread the virus during the first few days after recovery and sometimes for two weeks or more after all symptoms have disappeared.
How to Protect Yourself
There is no effective treatment for stomach flu. Drugs can't cure stomach flu, and antibiotics cannot help because the condition is caused by a virus. So prevention is the best medicine.
The best way to prevent being infected by someone else is by practicing proper hand hygiene. Wash your hands thoroughly with soap and water, especially before eating or after using the toilet and always before preparing or handling food. Practice food safety by carefully washing fruits and vegetables.
Read more: How to Avoid Catching a Stomach Virus
The Role of Vitamin C
Vitamin C is a water-soluble vitamin that acts as an antioxidant by neutralizing reactive oxygen molecules, called free radicals, that contribute to infections and disease. No recent studies have targeted an association between vitamin C and any viruses specific to gastroenteritis. Research reported in the Journal for Orthomolecular Medicine has determined, however, that infectious disease causes a depletion of vitamin C and greatly increases vitamin C requirements in the body.
Many studies have examined the role of therapeutic doses of vitamin C on the common cold and influenza and have found that daily supplementation may shorten the duration and severity of the illnesses. These results are promising leads for the potential use of vitamin C to have some biological effect on the stomach flu virus, as well.
With the antimicrobial and antioxidant properties in vitamin C, it makes sense that maintaining or supplementing your levels will help boost your immune system to help fight off the virus. Certainly, being deficient in vitamin C will likely have an adverse effect on your body's defense system, which could increase susceptibility to severity of infections.
Complications From Flu
The most serious complication of gastroenteritis is pneumonia. Research shows that supplementing with vitamin C may help with the pneumonia infection. A 2017 study published in Nutrients reported that three controlled trials found vitamin C prevented pneumonia.
Dehydration can result from stomach flu, and it's important to keep your fluid levels up. An old remedy is to drink 3 cups of grape juice for stomach flu. Research on the effectiveness of grape juice on stomach virus is inconclusive, but it may have some antiviral potential, at least in a petri dish, by decreasing the infectivity of viruses similar to norovirus.
Other vitamins for stomach flu that may help boost your immune system are beta-carotene and vitamin A, which has been found to be effective against the norovirus. Zinc, primarily in the form of lozenges, has been shown to reduce cold duration by 33 percent. In addition, zinc has been proven to be effective on acute lower respiratory tract infections.
Emergen-C and Stomach Flu
Emergen-C is a supplement that contains high doses of vitamin C in combination with other nutrients, such as B vitamins. Although it may support your immune system, there is no solid evidence that Emergen-C will treat stomach flu.
Be cautious if taking megadoses of vitamin C for relief from your stomach bug. High doses of vitamin C may cause diarrhea, nausea, vomiting and abdominal cramps — the very symptoms of stomach flu you are likely wanting to treat.
The National Center for Complementary and Integrative Health states there is no strong evidence supporting any natural product in the treatment or prevention of the flu. Instead, for the best means of protection, it recommends an annual flu vaccine.
Read more: Maximum Dosage of Vitamin C
Is This an Emergency?
- Centers for Disease Control and Prevention: About Norovirus
- Mayo Clinic: Viral Gastroenteritis (Stomach Flu)
- WebMD: Do I Have the Flu?
- Centers for Disease Control and Prevention: Norovirus: Prevention
- Centers for Disease Control and Prevention: Prevent the Spread of Norovirus
- Centers for Disease Control and Prevention: Norovirus: Transmission
- WebMD: Do I Have Pneumonia?
- Nutrients: Vitamin C and Infections
- Stop the Stomach Flu: Does Drinking Grape Juice Really Prevent Stomach Viruses?
- Gut Microbes: New Perspectives Regarding the Antiviral Effect of Vitamin A on Norovirus Using Modulation of Gut Microbiota
- BioMed Research International: Extra Dose of Vitamin C Based on a Daily Supplementation Shortens the Common Cold: A Meta-Analysis of 9 Randomized Controlled Trials
- International Society for Orthomolecular Medicine: High Dose Vitamin C and Influenza: A Case Report
- JRSM Open: Zinc Lozenges and the Common Cold: A Meta-Analysis Comparing Zinc Acetate and Zinc Gluconate, and the Role of Zinc Dosage
- Canadian Family Physician: Zinc Supplementation for Acute Gastroenteritis
- Mayo Clinic: Is It Possible to Take Too Much Vitamin C?
- National Center for Complementary and Integrative Health: 5 Tips: Natural Products for the Flu and Colds: What Does the Science Say?