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Safely Eating Oysters and Other Molluscan Shellfish

Food and Health Educators





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Image credit: Mississippi-Alabama Sea Grant via Flickr

Is it safe to eat raw oysters?


Most foods from animals are cooked prior to consumption. However, molluscan shellfish (oysters, clams, mussels) are often consumed raw or partially cooked. Illnesses sometimes occur from eating shellfish, and although most illnesses are typically not life threatening, instances of serious illnesses and deaths have been reported (see Introduction to Vibrio vulnificus). Eating raw shellfish can increase risk of illness – cooking can reduce the risk.

​​Who should avoid eating raw oysters?


Certain medically compromised individuals have an increased risk of serious illness or death from eating raw molluscan shellfish. Although these illnesses and fatalities are rare, medically compromised individuals should not eat raw or undercooked molluscan shellfish. At greatest risk are persons with liver, stomach, or blood disorders; individuals with AIDS, diabetes, cancer, or kidney disease; and chronic alcohol abusers. Those uncertain of their health status should seek the advice of their physician before eating raw shellfish.

Why are cooked oysters safer to eat than raw ones?


Thorough cooking kills bacteria and viruses that may cause illness.

Is it safe to eat oysters that I harvest?


Only if you harvest the shellfish from waters approved by state or local regulatory agencies. Please refer to the section about self-harvesting on the "Safely Buying Oysters and Other Molluscan Shellfish" webpage for additional information.

What about eating raw oysters during months with the letter "R"?

An old myth specifies the best time to eat oysters is during months that contain an "R" (i.e. September through April) and to avoid eating oysters in months that do not contain an "R" (May through August).

While levels of certain naturally occurring marine bacteria, like Vibrio, are higher in coastal waters during warm weather months, the bacteria may still be present, although in lower levels, during cold weather months.

While most consumers are not susceptible to infection by Vibrio vulnificus, consumers who have certain illnesses or health conditions (see above list) should only eat molluscan shellfish that is cooked and abstain from eating it raw or partially cooked, regardless of the month.


Because heat kills harmful bacteria and viruses, thoroughly cooked oysters, clams, and mussels are safe for anyone to eat all year, as long as they are legally harvested.

Is it safe to eat previously shucked shellfish raw?


No. Shellfish that has been shucked (removed from shells) and placed in plastic or glass containers is intended to be cooked and should not be eaten raw.

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Page last updated: November 5, 2017

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