Humans have been consuming raw oysters as far as 164,000 years ago. In the US, oysters were primarily considered affordable food for the middle and working class during the early 19th century. Though the demand for oysters has dropped, people still consume them, and there are raw oysters health risks that one needs to be aware of.

Oysters do not pose any health risks when consumed after cooking unless you have a food allergy. But it is not the same case when eating raw oysters.

What is inside an oyster?

Oysters are shellfish that are soft and slimy. They taste like the ocean. This is mainly because oysters are usually found in marine or brackish waters. These waters expose oysters to a lot.


Oysters can be exposed to natural bacteria in the water they live. These bacteria do not affect them but the humans who consume them.


Having a shell does not make oysters immune to parasites in water. Consuming raw oysters also means consuming an unknown parasite in them.


The water from which the oyster gets harvested may be infected with viruses from the feces of humans or animals. 


Apart from all this, oysters can be contaminated by the person handling their harvesting if using unclean hands.

All these factors can lead to raw oysters health risks.

What are the raw oyster risk factors?

Consuming raw oysters can cause foodborne diseases like:

Vibriosis – caused by the Vibrio bacteria found in the waters oysters are cultivated from. Symptoms develop within 12 to 72 hours and include:

  • Skin rashes
  • Blisters
  • Shaking chills
  • High fever. 

Hepatitis A – caused due to a weakened immune system. Symptoms might not start until 15-50 days and include:

  • Yellowing of the skin 
  • Yellowing of the whites of the eyes

General raw oysters health risks include:

  • Vomiting
  • Diarrhea
  • Nausea
  • Stomach pain
  • Severe weakness
  • Death (in rare cases)

Who should not eat raw oysters?

People with great immune systems rarely face health risks from eating raw oysters. But it is not the same case for others. Consuming raw oysters cause serious illness and in some cases, even death in people with the following health conditions.

  • Liver disease
  • Alcoholism
  • Diabetes
  • HIV 
  • Cancer, specifically lymphoma, leukemia, and Hodgkin’s disease
  • Achlorhydria
  • Hemochromatosis/hemosiderosis
  • Chronic bowel and stomach diseases
  • Steroid dependency
  • Anyone who is immunocompromised

How to avoid it?

It is a myth that adding lime juice, salt, or Tabasco sauce to raw oysters will kill any harmful bacteria in them. Only cooking oysters in boiling water will kill the disease-causing bacteria in them. Therefore, always prefer cooked oysters over raw oysters. 

Experts say that summer months are the most suitable for the disease-causing bacteria to survive in water. Hence infections from consuming raw oysters are high during this season. Avoid eating raw oysters during the summer.

Finally, is it safe to eat raw oysters?

People who are immunocompromised/ have a weak immune system should steer clear of eating raw oysters. Your body’s immunity decides the raw oyster health risks you may face. If you are facing any of the above symptoms from consuming raw oysters, kindly consult your doctor immediately.