Side Effects of Eating Oysters

Understanding the risks of eating oysters can help you avoid reactions.
Image Credit: Plateresca/iStock/GettyImages

Oysters may be a regular part of your summer, but an upset stomach after eating oysters can put a real damper on your warm weather fun. While it's possible that your oyster side effects could indicate an allergy, if you've been eating raw oysters, it may be food poisoning.


Eating Raw Oysters Side Effects

People have been eating oysters for over 2,000 years, according to Food Source Information at Colorado State University. These bivalve mollusks are filter feeders and consume about 25 gallons of water a day. While oysters support a healthy coastline and help keep the water clean, as filter feeders they also harbor pathogens that can make you sick.

Video of the Day

According to the Centers for Disease Control and Prevention (CDC), every year nearly 80,000 people get sick from eating raw or undercooked oysters, and as many as 100 people die. Various strains of Vibrio bacteria are responsible causing illness, and the signs and symptoms may develop within 24 to 48 hours after eating the contaminated oysters. How sick you get may depend on the strain responsible for the infection.


If you have an upset stomach after eating oysters, you may be infected with Vibrio parahaemolyticus. This strain causes only a mild infection resulting in side effects such as diarrhea and vomiting. If you've consumed raw oysters contaminated with Vibrio vulnificus_,_ the infection can be more serious. This strain of Vibrio can lead to a blood infection, development of blistering skin lesions, limb amputation or even death.

No matter the severity of your symptoms, if you're feeling sick after eating raw oysters you should contact your primary care provider for an evaluation and treatment plan. Unfortunately, there's no evidence that antibiotics can help your infection, according to the CDC, but in severe cases antibiotics may be prescribed anyway.


Read more: Oysters Are Good for You, but Be Careful How You Serve Them

Could It Be an Allergy?

Shellfish, such as oysters, are one of the most common food allergens. If you have an upset stomach after eating oysters, whether raw or cooked, it may be an allergic reaction. You can develop an allergy to shellfish at any age, but it most often develops in adults, according to Mayo Clinic.


Allergies refer to an overreaction of your immune system to a substance it considers harmful, even though for most people it's not. Allergic reaction symptoms usually develop within minutes to an hour after eating the oysters. Your allergy symptoms may include:


  • Hives
  • Abdominal pain
  • Diarrhea
  • Swelling of your lips, tongue or throat
  • Wheezing
  • Dizziness

In severe cases, your oyster allergy may lead to anaphylaxis, which is a life-threatening condition that may cause shortness of breath or loss of consciousness, and requires immediate medical attention. Talk to your doctor if you suspect you have an allergy to oysters so you can get a formal evaluation, diagnosis and treatment plan.


Read more: 3 Benefits of Eating Smoked Oysters and Potential Risks

Reducing Risk of Side Effects

If you've gotten sick from oysters, what to do may depend on the underlying cause of your illness. For an allergy, you will need to cut oysters — and probably other types of shellfish — from your diet to prevent the allergic reaction. Even if your initial side effects are mild, a more severe reaction can occur at any time.


It's impossible to know from sight or smell if an oyster is contaminated with a pathogen. The best way to reduce your risk of getting sick is to always completely cook your oysters before eating them, says the CDC.

Before popping your oysters in the pot, be sure to discard any mollusks with open shells. To kill the pathogens, boil your oysters until the shells open and then cook for another three to five minutes. If you've already shucked your oysters, you can safely eat the shellfish after it's been boiled for three minutes. Always wash your hands with soap and water after handling raw oysters. And despite what friends and family may say, hot sauce and lemon juice won't kill the bacteria.




Report an Issue

screenshot of the current page

Screenshot loading...