Skip to main content
Doctor licensed in Puerto RicoOnly for patients physically in Puerto RicoEmergencies: 911About us
Telehealth — The Health InitiativeEspañol

Stomach bug (gastroenteritis) in adults: what to do and when to worry

A stomach bug in adults is usually viral gastroenteritis, an infection of the stomach and intestines that causes diarrhea, vomiting, nausea and belly cramps. Most people get better in one to three days; the key is sipping an oral rehydration solution so you don’t get dehydrated. By video, the doctor can advise you and tell you if you need more. Blood in your stool, keeping nothing down or barely urinating need in-person care.

Can we help by telehealth? Sometimes: it depends on the evaluation.

Is this an emergency?

This is not an emergency service. Call 911 or go to the nearest emergency room if you have:

  • Blood in the stool or vomit
  • Can’t keep fluids down
  • No urine for 8 hours or more
  • Dizziness or fainting when standing up
  • Confusion or unusual drowsiness
  • Severe, constant belly pain
  • Vomiting 3 or more times in 24 hours after days of fever (possible dengue)

Help lines:

Warning signs: when to go to the ER

Book a visit

Stomach bug symptoms in adults

Symptoms usually start 4 to 48 hours after exposure. The most common are:

  • Diarrhea
  • Vomiting
  • Nausea
  • Belly pain or cramps
  • Fever
  • Headache and body aches

Causes, including for visitors: norovirus, rotavirus and food

The most common cause of diarrhea in adults is norovirus, which is highly contagious and causes outbreaks in hospitals, schools and on cruise ships. In young children, rotavirus is the leading cause. It spreads through contact with a sick person, contaminated food or water, and shared surfaces and utensils. COVID-19 can also cause stomach symptoms.

Although it is called "stomach flu", it isn’t caused by the flu virus. Most people with norovirus get better within 1 to 3 days. Young children, older adults and people with weakened immune systems are at higher risk of complications.

Hydration at home with oral rehydration solution

The most important thing is replacing lost water and salts. Drink an oral rehydration solution (an electrolyte solution from the pharmacy) even if you can eat, and drink it between meals.

Sip slowly, in small, frequent amounts, following the label. Drinking a lot at once can bring on more vomiting. Skip juice, soda, flavored gelatin and broth: they don’t replace lost salts and can make diarrhea worse.

When you are hungry, eat small amounts often: cereals, bread, potatoes, lean meat, plain yogurt, bananas and vegetables. If you take a diuretic (water pill), ask your doctor whether to pause it while you have diarrhea; never stop a prescription medicine without checking.

When medication helps

Rarely. Antibiotics don’t work against viruses. Over-the-counter medicines can slow diarrhea, but don’t use them without talking to a doctor if you have bloody diarrhea, fever or severe diarrhea, and don’t give them to children.

In an online doctor visit (US$79), the doctor checks whether you are dehydrated, whether anything points to a cause other than a virus, and whether a medicine would help, for example for nausea. If appropriate, the doctor can prescribe medication. We do not prescribe controlled substances.

In Puerto Rico: water, cruises and dengue

After a hurricane or flood, drink bottled, boiled or treated water. To boil it, the CDC says to bring clear water to a rolling boil for 1 minute.

Norovirus outbreaks are common on cruise ships; if you arrived in San Juan on a cruise and are sick, see a doctor for cruise passengers. Other visitors can also book a video visit while on the island; see our guide for visitors.

In Puerto Rico, vomiting 3 or more times in 24 hours, together with belly pain, is also a dengue warning sign, especially after a few days of fever. In that case go to the ER. Read dengue warning signs.

If your child has diarrhea and vomiting

This page is for adults. Babies and young children dehydrate faster and the warning signs depend on age: see our page on diarrhea and vomiting in children. Don’t give children over-the-counter diarrhea medicines. A baby under 3 months with a temperature of 100.4 °F (38 °C) or higher needs medical care right away.

The doctor sees children from 6 months with a parent or legal guardian on camera, and she is not a pediatrician; see video visits for children.

When to go in person or to the ER

Get in-person care or go to the ER if you have:

  • Blood in your stool.
  • Vomiting that stops you keeping fluids down.
  • Little or no urine for 8 hours or more, or very dark urine.
  • Dizziness or feeling faint when you stand up.
  • Confusion.
  • A very dry mouth, sunken eyes or no tears.
  • Diarrhea lasting more than several days.
  • High fever, or you are older or have a weakened immune system and are getting worse.

Prevention and doctor’s notes

Wash your hands with soap and water for at least 20 seconds, especially after using the bathroom and before handling food: hand sanitizer doesn’t work well against norovirus. Clean contaminated surfaces with a bleach solution (5 to 25 tablespoons of household bleach per gallon of water) and leave it on for at least 5 minutes. Don’t prepare food for others or care for other people until 48 hours after your symptoms stop. Rotavirus vaccine is recommended for babies starting at 2 months.

If you missed work, the doctor can give you a doctor’s note after a real visit, at no extra charge beyond the visit.

Video visit: US$79 · Pay by card · See the price and what is included

Before you book

  • You must be physically in Puerto Rico during the visit (visitors and tourists are welcome).
  • We see patients from 6 months old. Patients under 21: a parent or legal guardian must be on camera for the whole visit.
  • Real-time video only; we do not do phone-call visits.
  • We do not prescribe controlled substances.

What we don't do by telehealth

Frequently asked questions

How long does a stomach bug last?
Most people with norovirus get better within 1 to 3 days, and most viral stomach bugs clear on their own in a few days. If diarrhea lasts more than several days or you show signs of dehydration, get care.
What should I drink when I have diarrhea and vomiting?
An oral rehydration solution in small, frequent sips, following the label. Avoid juice, soda and broth, which don’t replace lost salts. If you can’t keep any fluid down, you need in-person care.
Can I take something to stop the diarrhea?
Over-the-counter diarrhea medicines exist, but don’t use them without medical advice if you have blood in your stool, fever or severe diarrhea, and don’t give them to children. Antibiotics don’t work against viruses.

Sources

Related pages

Lea esta página en español