Signs and Symptoms of Stomach Flu

The stomach flu—medically known as viral gastroenteritis—is an infection that causes symptoms like nausea, diarrhea, and abdominal pain. This contagious infection primarily affects the gastrointestinal (GI) tract, which is a long tube that connects all the organs from your mouth to your anus, including your esophagus, stomach, and intestines.

When you contract the virus, symptoms can develop rapidly—sometimes within a few hours of exposure. But in some people, symptoms may be mild and gradually get worse over the next few days. Generally, the stomach flu lasts for less than a week and symptoms start to improve after three days.

Nausea and Vomiting

Nausea and vomiting are usually the first symptoms of stomach flu that you experience. It's important to understand that nausea typically happens before any vomiting episodes. You can try to prevent vomiting by avoiding solid foods, drinking clear liquids (such as water or sports drinks with electrolytes), and getting rest.

If you experience persistent or severe nausea or vomiting, you might also develop dehydration, which requires medical attention. Staying hydrated and slowly introducing bland foods (like toast and rice) can help prevent dehydration and aid in your recovery.

Diarrhea

Most people who contract the stomach flu also experience diarrhea, which can cause loose, frequent, and watery stools (poops). Diarrhea typically lasts less than a week, and drinking water can help prevent dehydration and improve your poop quality.

Extreme or prolonged diarrhea can lead to dehydration which, in more serious cases, may require medical attention to prevent complications. Recovery often involves allowing the digestive system to rest and gradually reintroducing easily digestible and bland foods. In some cases, your healthcare provider may recommend taking a probiotic to help improve your diarrhea more quickly.

Abdominal Pain or Cramps

The stomach flu virus is known to cause some type of abdominal pain. The pain may feel like uneasiness, discomfort, or cramping in the stomach region. The pain often results from inflammation in your GI tract.

Headache

It's common to experience a headache or other types of body aches when you contract the virus. In most cases, drinking water and getting sleep can improve symptoms. But if your pain persists, over-the-counter pain relievers like Advil (ibuprofen) can help alleviate the pain.

Fatigue

When you get sick, it's natural for your body to feel fatigued or tired. Fatigue often occurs because it's your body's automatic immune response to the infection. Getting enough rest helps your body heal and improves fatigue as your infection clears up.

Muscle Aches

Muscle aches (also known as myalgia) often occur alongside other stomach flu symptoms. Your immune system is hard at work trying to fight off the virus and muscle pain can occur due to your immune system's natural inflammatory response to infection. With rest, proper hydration, and gentle stretching, muscle aches will usually go away within a few days.

Fever

Though not everyone develops a fever with the stomach flu, some people can experience this symptom. Like muscle aches, a fever occurs due to an inflammatory immune system response. Usually, a fever will go away on its own in a couple of days with rest, hydration, and over-the-counter fever reducers. But if your fever is greater than 102 degrees Fahrenheit (or 39 degrees Celcius), talk to your healthcare provider, as this may be a sign of a more serious condition

Symptoms in Children

If your child develops the stomach flu, it's important to contact their healthcare provider promptly. Symptoms like vomiting and diarrhea, especially for newborns and infants, post a significant risk of dehydration. Persistent vomiting and diarrhea can lead to severe dehydration within a span of just one or two days.

If you're a parent or caregiver and notice any of the following signs of the stomach flu in an infant or child, talk to a healthcare provider right away:

• Persistent vomiting
• Diarrhea that lasts for more than a day
  
• Increased irritability or restlessness
• Reduced energy levels
• Fever
  
• Severe abdominal or rectal pain
• Symptoms of dehydration

Signs of dehydration in children and infants may include:

• Dry mouth
• Lack of tears when crying
• Loss of skin elasticity
• Sunken appearance around the eyes and cheeks

When to Contact a Healthcare Provider 

Most of the time, viral gastroenteritis isn't a serious condition, as many people experience symptoms each year. However, the stomach flu can become serious if you become dehydrated. Severe dehydration might induce a trip to the hospital for proper care.

It's a good idea to contact a healthcare provider if you experience:

• Changes in mental state, such as increased irritability or diminished energy levels
• Diarrhea that persists beyond 48 hours
• High fever
• Frequent vomiting
• Intense abdominal pain
• Bloody poop or dark-colored stools
• Dehydration
  

Pregnant people, older adults, and people with autoimmune conditions should also seek medical attention if they have symptoms of the stomach flu—as they may be more likely to experience complications or severe symptoms.

A Quick Review 

Stomach flu, or gastroenteritis, is a viral infection that causes symptoms like nausea, diarrhea, and abdominal pain. While usually not severe, the illness can lead to dehydration, especially in infants and young children. Fortunately, this infection is not usually serious and you can find relief from your symptoms by getting rest, drinking water, and eating bland foods.