Food Poisoning: Symptoms, How Long It Lasts, and When to Get Help

Food poisoning usually causes nausea, vomiting, diarrhea and stomach cramps, starting anywhere from a few hours to a few days after eating contaminated food. Most cases pass on their own in a day or two, and the main job is keeping up with fluids. Get help if you can't keep liquids down, show signs of dehydration, have bloody diarrhea or a high fever, or aren't improving after a few days.

What causes food poisoning?

Food poisoning comes from bacteria, viruses, parasites or toxins in food or drinks. Common culprits include norovirus, salmonella, E. coli and campylobacter. Undercooked meat and eggs, unwashed produce, raw shellfish, unpasteurized milk and food left out too long are frequent sources. A stomach virus passed from person to person can look exactly the same, and from the outside it often isn't possible to tell which one you have.

Food poisoning symptoms

• Nausea and vomiting
• Watery diarrhea
• Stomach cramps or pain
• Low fever, chills, headache or body aches
• Feeling weak or tired

How long does food poisoning last?

It depends on the cause. Some kinds start within a few hours of eating and are over in a day. Others take a day or more to start and can last several days. Most people feel better within a day or two. Diarrhea that lasts more than three days, or symptoms that are getting worse instead of better, should be checked.

How to stay hydrated

Dehydration is the main risk with food poisoning, especially for young children, older adults and anyone who is pregnant.

• Take small, frequent sips rather than big gulps.
• An oral rehydration solution from the pharmacy replaces salts as well as water. Broth and diluted sports drinks can help adults.
• If you're vomiting, wait a little after each episode, then start again with a few sips.
• Ease back into bland foods when you're ready.
• Avoid alcohol and caffeine until you're better.

Check with a clinician or pharmacist before taking anti-diarrhea medicine, especially if you have a fever or blood in your stool, and before giving any to a child.

Signs of dehydration

• Peeing much less than usual, or dark urine
• A very dry mouth and lips
• Dizziness or lightheadedness when standing
• A fast heartbeat
• In babies and young children: few wet diapers, no tears when crying, unusual sleepiness

When to get help for food poisoning

See a clinician the same day if you:

• Can't keep fluids down for several hours
• Have signs of dehydration
• Have a fever that's high or lasting
• See blood in your stool
• Have diarrhea for more than three days
• Are pregnant, older, have a weakened immune system, or the sick person is a young child

A clinician can check how dehydrated you are and offer anti-nausea medication. If you can't keep fluids down, IV fluids in the clinic can replace what you've lost, usually over about an hour. When diarrhea is bloody or lasting, they may test a stool sample. Our stomach bug page covers what a visit involves.

Mild cases can often be handled by telehealth: a video visit with an AfterOurs clinician is $75 self-pay, available 8 AM to 11 PM daily, and the clinician will tell you if you need to come in. In the clinic, a standard self-pay visit is $175, and a self-pay in-clinic visit never costs more than $330. We contract with all major commercial and government plans, including Colorado Medicaid and Medicare. We can't guarantee a particular commercial plan has us in network; if it's out of network or denies the visit, we drop you to the self-pay rates. See our cost and insurance page.

Call 911 or go to the ER if you have signs of severe dehydration, such as no urine for 8 hours or more, fainting or confusion; blood in your vomit or black or bloody stools; severe or constant belly pain; or blurred or double vision, drooping eyelids, slurred speech, trouble swallowing or muscle weakness. In a baby, go for no wet diapers, a sunken soft spot or unusual sleepiness.

Where to find us

Four clinics across metro Denver, all ages welcome, se habla español:

• Hampden (Southeast Denver): 8 AM–11 PM daily
• Littleton: 8 AM–11 PM daily
• Thornton: 8 AM–11 PM daily
• Highlands: Mon–Fri 5–11 PM, Sat–Sun 8 AM–11 PM

Walk in, or book online.