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Are Raw Oysters Worth the Risk?

Posted in Our Blog,Outbreaks & Recalls,Vibrio on July 1, 2023

Oysters season is nearly upon us again. Just a few hot months and then temperatures drop again (we hope). According to the old wives’ tale, you should only eat oysters in months that contain an “R”. This includes September through April. Is there any truth in that?

Is There Truth to the Old Wives’ Tales?

So, is there any truth to the Old Wives’ Tale? You should only eat oysters in months that contain the letter “R”? Yes and no. Vibrio vulnificus, one of the big bacteria that can make people sick from eating oysters, thrive in warm waters. More bacteria means greater risk.

Other bad bugs can join the party due to contamination. So Vibrio isn’t the only baddie on the block. Salmonella, E. coli, and others are happy to join the party in cases of cross-contamination.

How about the notion that hot sauce kills bacteria? Wouldn’t that be an awesome solution to all foodborne illness risk. Jonathan Weathington, CEO of Shuckin’ Shack says this is his favorite myth. He says that drowning oysters in hots sauce does about the same as running them under water. Coating the surface does nothing for what is going on inside. “And while pairing them with a bottle of wine is common,” he says, “alcohol won’t kill any bacteria either.” Cooking at the right temperature for the correct length of time is the only that that will kill any harmful bacteria.

FDA Guidelines to Reduce Risk

In an effort to reduce the risk of bacterial foodborne illness, the United State Food and Drug Administration (FDA) has created a membership program that, in a way, provides a type of accreditation for those in the shellfish industry. This membership helps resellers and food service businesses a way to choose the safest shellfish options.

National Shellfish Sanitation Program (NSSP)

The National Shellfish Sanitation Program, or NSSP creates a list of rules outlining safe practices and controls for handling shellstock. These rules, known as the National Shellfish Sanitation Program (NSSP) Guide for the Control of Molluscan Shellfish, fill a 502 page tome apply to the entire starting from the shellstock growers to harvesting to transportation and processing, all the way to preparation.

A contingency for membership is an agreement to complying with the components of the guide.

Reputable businesses lean on this membership program to ensure that safe shellstock are provided to their patrons. Weathington cites the benefits of the program. The old wives’ tale and other myths are fairly irrelevant, allowing food shops to provide shellstock year-round. The warm waters might increase risk, but refrigeration helps mitigate that risk.

Choosing suppliers that follow these FDA guidelines allows for a safer product, regardless of which letters appear in the month. “Warmer-than-average waters increase the likelihood of Vibrio vulnificus, the bacteria that can cause people to get sick after eating oysters. But in line with FDA guidelines, Shuckin’ Shacks’s suppliers begin cooling oysters as they’re harvested, so no matter if it’s July or December, oysters are safe to eat,” says Weathington.

“When you’re dealing with a controlled population of oysters, they’re being cooled right away. You’re not serving raw oysters sitting out in the sun after being harvested,” he continues. “Because we’re dealing with more aquacultured oysters, they’re safe to eat year-round,” said Weathington.

He explains that when harvested before 10:00AM and cooled properly to an appropriate 45°F, a “temperature that’s maintained through the oyster’s life before it’s served, then there should be no illness.”

“Illness comes when that cold chain is broken,” says Tom Perry, president of White Stone Oysters. “And if you’re working with a good supplier, that’s not going to happen.”

The Raw Debate

 There are plenty of people who scoff at the risk as they swallow their slimy sea boogers. But if the supplier is a member of the NSSP and pinky promises with a cherry on top that they will maintain temperatures, is it safe to eat raw oysters.

The answer is a resounding no.

Will everyone get sick? Probably not. Will some people get sick? Sadly, yes.

“There’s always going to be a small amount of risk,” says Dr. Fred Lopez, who studies infections diseases at LSU’s Heath Sciences Center.

Dr. Lopez explains that the bacterial risk found in oysters is more common in oysters harvested in the warmer waters of the Gulf of Mexico compared to the East and West coasts. “If you’re consuming a raw oyster that comes from the Gulf Coast waters… particularly in the summer months,” says Lopez. “You have to assume that it has Vibrio vulnificus.

Some People Are More Vulnerable

Certain people are at a higher risk of becoming sick after consuming contaminated oysters. These folks should not consume raw oysters, and should be cautious with all high-risk foods.

Those with liver disease, alcoholism, diabetes, kidney disease, or the blood disorder thalassemia. Also, those with cancer, people under chemotherapy treatment, HIV, and those with an otherwise weakened immune system due to medication, pre-existing condition, or some other factor. Those over the age of 65, or who have had recent stomach surgery, or take medications to lower stomach acid levels are also at higher risk.

If someone with a weakened immune system becomes infected with Vibrio vulnificus, there is about a 33 – 50% chance it will become fatal. Even in normally healthy individuals, there is a 1 in 5 chance of mortality.

 How About Cooked?

How about cooked oysters? Are they safe?

I thought you’d never ask!

Oysters, even those exposed to Vibrio vulnificus, aren’t necessarily off limits. Cooking can kill those harmful bacteria. Boil them. Fry them. Steam them. Bake them. Grill them. Smoke them. Cook them in soups, stews, and other dishes. The key is to cook them hot enough and long enough to kill the bad bacteria lurking within.

What is Vibriosis?

What exactly is vibriosis and how bad is it?

Vibriosis is the illness associated with infection of certain types of Vibrio bacteria, including Vibrio vulnificus, commonly known in raw oysters. This bacteria naturally lives in coastal waters and infect oysters by the way that oysters eat. Oysters filter water through themselves, which can cause bacteria and other germs to concentrate in their tissues. Consuming raw or undercooked oysters can cause illness in humans. Vibriosis is serious!

The Centers for Disease Control and Prevention (CDC) estimates that around 80,000 people get sick with vibriosis each year. And 100 will die. Onset of illnesses generally hoovers around May through October when water temperatures are warmer.

According to the CDC, “an oyster that contains Vibrio vulnificus doesn’t look, smell, or even taste different from any other oyster.”


Most infections result in mild digestive illness, consisting of watery diarrhea with abdominal cramping, vomiting, fever and chills. Symptoms often begin within 24 hours of ingestion and can last around 3 days.

Some infections can be quite serious. This is because Vibrio vulnificus can lead to bloodstream infections, severe skin blistering, and limb amputations. Also, death.

Tips for Cooking Oysters and Other Shellfish

Cooking oysters and other shellfish properly is the only safe way to consume them. A few safety tips and appropriate cooking times is all that is needed.

Before cooking, inspect your shellfish. Discard any that already have open shells.

Cooking Shellfish in the Shell

When cooking shellfish in their shell, you have two good options, boil or steam. If boiling, boil until the shells open and continue boiling for another 3-5 minutes. If steaming, add to a steamer when water is already steaming and cook for 4-9 minutes.

IMPORTANT: Only eat shellfish that open during cooking. Discard any that do not open fully after cooking.

Cooking Shucked Oysters

You’ve got quite a few good options when cooking shucked oysters. Think in 3’s. Boil for at least 3 minutes, fry in oil for at least 3 minutes at 375 °F, or broil 3 inches from heat for 3 minutes. You can also bake them at 450 °F for 10 minutes.

Enjoy Safely

In summary, raw oysters are always a risk. Even more so for those in more vulnerable groups. Cooking oysters at appropriate temperatures for appropriate amounts of time is the only way to consume it safely. If you choose to consume oysters raw, despite increased strict guidelines for handling shellstock, keep to months where the waters aren’t so warm or from areas of less risk. Monitor yourself for symptoms of vibriosis after consuming raw oysters.