The Potential Side Effects of Eating Oysters

Side Effects of Eating Raw Oysters

Raw oysters offer big health benefits, serving as an excellent source of protein, Vitamin B-12, copper, zinc, and selenium. However, they also cause thousands of people to get sick each year, according to the Centers for Disease Control and Prevention (CDC).

As filter feeders, these bivalve mollusks consume about 25 gallons of water a day. While oysters support a healthy coastline and help keep the water clean, they can also harbor pathogens that can make you sick.

Eating raw or undercooked oysters can put you at risk for an infection called vibriosis, which is caused by various strains of Vibrio bacteria in contaminated shellfish. Most healthy people who get vibriosis experience diarrhea and vomiting within 24 to 48 hours of exposure, but some cases are life threatening, with 1 in 5 people dying from the infection. People with compromised immune systems and certain chronic health conditions are more susceptible to severe reactions, according to Kaiser Permanente.

Eating raw oysters can also lead to norovirus and hepatitis A infections, according to the Virginia Department of Health. Symptoms can include vomiting, diarrhea, nausea, stomach pains, and severe weakness, as well as yellowing of the skin and eyes in hepatitis A cases.

No matter the severity of your symptoms, if you feel sick after eating raw oysters, contact your healthcare provider for an evaluation and treatment plan.

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 usually harmless substance. For people who are allergic to oysters, symptoms typically develop within minutes to an hour after eating them. Symptoms may include:

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

In severe cases, an oyster allergy may lead to anaphylaxis, 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.

How to Reduce Your Risk of Side Effects

If you've gotten sick from eating oysters, what to do next may depend on the underlying cause of your illness.

If you’re allergic to oysters, you will need to eliminate them (and potentially other types of shellfish as well) from your diet to prevent future reactions, according to Mayo Clinic. 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 like Vibrio bacteria. The best way to reduce your risk of getting sick is to cook your oysters thoroughly before eating them, according to 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, then cook them for another 4–5 minutes. If you've already shucked your oysters, you can safely eat the shellfish after it's been boiled for 3 minutes.

Always wash your hands with soap and water after handling raw oysters.