By Christopher Prior, DO, FAAFP, CAQSM, a physician at Sheridan Memorial Hospital’s SameDay Health & Imaging clinic.
Food poisoning is an unpleasant — and sometimes serious — condition that affects millions of people each year. Understanding how long it can take for symptoms to appear after eating contaminated food may help identify the cause and determine when medical care is needed.
Common causes, symptoms
Food poisoning occurs when food or beverages are contaminated with harmful bacteria, viruses, parasites or toxins. Common causes include Salmonella, E. coli, norovirus and Listeria. Symptoms can range from mild gastrointestinal discomfort to severe illness requiring medical attention.
Common symptoms of food poisoning include:
- Diarrhea
- Nausea
- Vomiting
- Abdominal cramps
- Fever
When do symptoms start?
The time between eating contaminated food and developing symptoms varies depending on the type of contaminant involved.
- Salmonella
- Common sources: Poultry, eggs, unpasteurized milk and contaminated produce
- Symptom onset: Six hours to six days
- Typical duration: Four to seven days
- E. coli
- Common sources: Undercooked beef, raw vegetables and contaminated water
- Symptom onset: One to 10 days (most commonly three to four days)
- Typical duration: Five to 10 days
- Norovirus
- Common sources: Contaminated water, shellfish and infected food handlers
- Symptom onset: 12 to 48 hours
- Typical duration: One to three days
- Listeria
- Common sources: Deli meats, hot dogs, dairy products and smoked seafood
- Symptom onset: One to four weeks (in some cases, up to 70 days)
- Typical duration: Varies
When to seek care
Several factors can influence how quickly symptoms appear and how severe they become, including the amount of contamination and a person’s age, immune system and overall health.
While many cases of food poisoning resolve on their own, medical attention may be needed if you experience:
- Persistent vomiting
- High fever
- Signs of dehydration
- Severe abdominal pain
- Symptoms lasting longer than three days
Certain individuals are at higher risk for complications, including infants, older adults, pregnant women and people with weakened immune systems. These individuals should seek medical care promptly if food poisoning is suspected.
This article originally appeared in The Sheridan Press on May 4, 2026.