Common Stomach Bug Symptoms
Symptoms often start suddenly, usually 12 to 48 hours after exposure. Most people have some combination of:
- Nausea and vomiting
- Watery diarrhea
- Stomach cramps or pain
- Low-grade fever
- Chills, headache and body aches
- Loss of appetite
- Fatigue
Diarrhea from a typical stomach bug is watery. Bloody diarrhea is not typical and needs medical evaluation.
How Long Does a Stomach Bug Last?
| Symptom | Typical timeline |
|---|---|
| Time from exposure to symptoms | About 12 to 48 hours (varies by virus) |
| Vomiting | Often the worst in the first 24 hours, then settles |
| Diarrhea | Commonly 1 to 3 days; may last a few days longer |
| Overall illness | About 1 to 3 days for most healthy adults |
| Fatigue and mild stomach upset | Can linger for several days to a week |
| Longer cases | Some viruses, children and people with weakened immunity may take longer |
Norovirus, the most common cause in adults, typically runs 1 to 3 days. Rotavirus is a common cause in young children, and vaccination has made it far less common. Duration depends on the virus, your age, your immune system and how much fluid you’ve lost.
Rule of thumb: You should feel clearly better each day. If you’re getting worse, or nothing improves after 2 to 3 days, get checked.
How Long Are You Contagious?
Stomach bugs spread easily, and you can spread norovirus before you feel sick. According to the CDC, people with norovirus are contagious from the moment symptoms start until at least 3 days after they recover, and some people stay contagious for up to 2 weeks.
To protect others:
- Wash hands with soap and water (hand sanitizer doesn’t reliably kill norovirus).
- Stay home until symptoms have stopped, and avoid preparing food for others for at least 2 days after you feel better.
- Clean surfaces with a disinfectant that is effective against norovirus. Bleach-based cleaners are commonly recommended.
- Wash soiled clothing and linens in hot water.
Stomach Bug vs. Food Poisoning
They look alike, but timing and spread differ.
| Stomach bug (viral) | Food poisoning | |
|---|---|---|
| Cause | Virus (norovirus, rotavirus, others) | Bacteria, toxins or other germs in food |
| Onset | Roughly 12–48 hours after exposure | Often within hours to a few days |
| Typical duration | 1–3 days | Often hours to 1–2 days (some types last longer) |
| Spreads person to person? | Yes, easily | Usually no, but several people who ate the same food can get sick |
Either one can cause dehydration. If you can’t tell which you have, or symptoms are severe, a medical provider can help sort it out.
Dehydration: The Real Risk
Vomiting and diarrhea drain fluids and electrolytes fast. Watch for:
Adults
- Dry mouth and extreme thirst
- Dark urine, or urinating much less
- Dizziness or lightheadedness, especially when standing
- Weakness or unusual fatigue
- Confusion (this is serious)
Children and babies
- Few or no tears when crying
- Fewer wet diapers or going many hours without urinating
- Dry mouth, sunken eyes
- Sunken soft spot on a baby’s head
- Unusual sleepiness, fussiness or limpness
Infants, young children, older adults, pregnant women and people with chronic conditions or weakened immune systems dehydrate faster and should get care sooner.
What to Do at Home
For mild to moderate illness where you can keep fluids down:
- Sip fluids often. Small, frequent sips of water, oral rehydration solution or broth work better than gulping.
- Rest. Your body is fighting an infection.
- Ease back into food. When nausea settles, start with bland, easy foods like rice, bananas, toast or crackers.
- Avoid alcohol, greasy or heavy foods, and (for many people) dairy and very sugary drinks until you’ve recovered.
- Ask before using medicine. Anti-diarrhea medicines aren’t right for everyone. They’re generally not recommended for young children and may not be safe if you have a fever or bloody stool. Check with a provider or pharmacist first.
When to Get Care for a Stomach Bug
Go to the ER or call 911 if:
- You are confused, extremely drowsy, faint or can’t be woken
- You have severe or worsening abdominal pain, especially one-sided or very hard, tender belly
- You’re vomiting blood or what looks like coffee grounds
- You have signs of severe dehydration and can’t drink at all
- You have a stiff neck with fever, a seizure, or trouble breathing
- A baby is limp, unresponsive or has a sunken soft spot with no wet diapers
Get same-day care (urgent care or your doctor) if:
- You can’t keep fluids down for about 24 hours
- You have signs of dehydration: dark urine, dizziness, dry mouth, little urination
- Vomiting or diarrhea lasts more than 2 days (adults) or you’re not improving after 2 to 3 days
- You have blood in your stool, or black, tarry stools
- You have a high or persistent fever
- You’re pregnant, over 65, or have a condition like diabetes, kidney disease or a weakened immune system
- A child or infant is vomiting repeatedly, hasn’t urinated in many hours, or seems unusually sleepy or irritable
- You recently traveled, took antibiotics, or symptoms keep coming back
Okay to manage at home if:
- You can keep down fluids
- You’re urinating normally
- Symptoms are mild and improving each day
- No blood, severe pain or high fever
When in doubt, get checked. For babies and young children, check sooner rather than later.
Why Symptoms That Last Longer Need a Closer Look
Most stomach bugs fade within days. Symptoms that drag on or keep returning may point to something else, such as a bacterial or parasitic infection, a medication effect, an intolerance, or in some cases a more serious problem like appendicitis. Belly pain that settles into one spot, worsens or comes with fever deserves prompt evaluation.
How Urgent Care Can Help
Sahara West Urgent Care & Wellness treats a range of acute illnesses, including stomach bugs, food poisoning and mild dehydration. At a visit, a provider can:
- Ask about your symptoms, how long they’ve lasted and what you’ve been eating, drinking and exposed to
- Check for signs of dehydration and examine your abdomen
- Use on-site lab testing when it’s needed
- Recommend a treatment and recovery plan
- Tell you if you need to go to the ER instead
You don’t need an appointment. If your symptoms are severe, don’t wait. Go to the ER.
Sick in Las Vegas? Walk In to Sahara West Urgent Care
Whether you live in Summerlin or Spring Valley or you’re visiting from the Strip, Sahara West is a walk-in clinic on West Sahara Avenue. See our urgent care services for the full list of what we treat.
📍 6125 W Sahara Ave, Suite 1B, Las Vegas, NV 89146
🕘 Mon–Fri 9am–8pm | Sat 9am–3pm
📞 Call (702) 248-0554
Walk in today or book an appointment →
We accept many insurance plans and offer self-pay options. See accepted insurance or ask about our membership plans. If we’re closed and you have severe symptoms, go to the nearest ER.
For ongoing digestive concerns or follow-up care, our primary care team can help. You can also read our guides on fever, chills and body aches and what to know before going to urgent care.
FAQs
How long does a stomach bug last?
Most last 1 to 3 days. Some last up to a week, and fatigue can linger a little longer.
How long does vomiting last with a stomach bug?
Vomiting is usually worst in the first day and often eases within 24 to 48 hours. Diarrhea can last a bit longer.
How long are you contagious with a stomach bug?
With norovirus, you’re contagious from the first symptoms until at least 3 days after you recover. Some people can spread it for up to 2 weeks.
What are the first signs of a stomach bug?
Sudden nausea, vomiting, watery diarrhea and stomach cramps, sometimes with a low fever, chills or body aches.
How can I tell stomach flu from food poisoning?
Food poisoning often starts sooner after a meal and tends to be shorter, and it usually doesn’t spread person to person. A stomach bug spreads easily between people. If you can’t tell, a provider can help.
When should I go to urgent care for a stomach bug?
Go if you can’t keep fluids down, you see signs of dehydration, symptoms last more than a couple of days, you have blood in your stool, or you’re in a higher-risk group (young children, older adults, pregnancy, chronic conditions).
When should I go to the ER for vomiting and diarrhea?
Go for severe or worsening belly pain, vomiting blood, confusion, fainting, severe dehydration you can’t fix by drinking, or a stiff neck with fever.
Can a stomach bug last more than a week?
It’s uncommon in healthy adults. If symptoms last more than a few days or keep coming back, get evaluated to look for another cause.
Can you get a stomach bug twice?
Yes. Different viruses cause similar illness, and immunity doesn’t always last.
What should I eat after a stomach bug?
Start with small amounts of bland foods like rice, bananas, toast or crackers, and keep drinking fluids. Avoid alcohol and greasy foods until you feel fully recovered.
Medical disclaimer: This content is for educational purposes only and isn’t a substitute for professional medical advice, diagnosis or treatment. If you think you’re having a medical emergency, call 911.
Sources: CDC: About Norovirus · CDC Norovirus Q&A (contagious period) · BCBS Michigan: Food Poisoning vs. Stomach Bug
