Nestled on beds of crushed ice alongside zesty condiments like lemon slices and cocktail sauce, oysters are often the star of the raw bar. Some seafood lovers consider the briny bivalves to be an aphrodisiac and wouldn’t dream of a happy hour without them.

But before you coax your next Kumamoto out of its shell, know this: According to the Centers for Disease Control and Prevention (CDC), raw oysters are responsible for an average of 85 hospitalizations and 35 deaths each year nationwide, mostly in the Gulf coast region which includes Alabama, Florida, Louisiana, Mississippi and Texas.

The culprit: a bacterium called Vibrio vulnificus that occurs naturally in warm seawaters and is the leading cause of death related to eating seafood in the United States, according to the American Academy of Family Physicians. For someone whose immune system is compromised, V. vulnificus can cause severe symptoms including fever, chills, septic shock (when a body-wide infection leads to dangerously low blood pressure) and blistering skin lesions, explains Kristen Nordlund, public affairs officer at the National Center for Emerging and Zoonotic Infectious Diseases at the CDC. Such folks have a 50 percent risk of dying from an infection due to V. vulnificus, which can happen as quickly as within two days of eating raw seafood.

For this reason, people with diabetes, cancer, HIV/AIDS, kidney disease or liver, stomach or blood disorders should never eat raw oysters or raw seafood in general. The same is true for anyone who’s had an organ transplant and for pregnant women, says Lauren Sucher, spokesperson for the Food and Drug Administration (FDA).

Related: Food Safety Fails: 10 Common Mistakes That Could Make You Sick

A healthy person who’s exposed to V. vulnificus may experience vomiting, diarrhea and stomach pain that’s unpleasant but temporary. So in general, it’s relatively safe to slurp down a few Blue Points — and even nutritionally smart: Oysters are a great source of heart-healthy omega-3 fatty acids.

Read on for more about the safety of raw oysters.

Kill by cooking. The only way to completely avoid bacteria in oysters is to cook them. “V. vulnificus are not the result of pollution, so while it’s important to buy oysters from a reputable fishmonger, eating them from supposedly clean bodies of water or in busy restaurants that serve them raw all the time does not guarantee protection,” says Nordlund. To be absolutely safe, bake oysters for 10 minutes at 450 degrees Fahrenheit, broil them 3 inches from the heat source for 3 minutes or fry them at 375 degrees Fahrenheit for at least 3 minutes.

Forget about months with an “R.” The oft-repeated advice to eat oysters only in months that contain the letter “R” (September to April) lives on, yet this recommendation holds no water. The thinking was that oysters harvested during the colder part of the year would not contain harmful bacteria that’s found in higher concentrations in warmer months (May to August). Unfortunately, this bacterium is still found in coastal waters in “R” months and according to the FDA, 40 percent of cases of V. vulnificus infection occur at this time.

Related: Farmed Fish: Yay or Nay?

The nose does not know. Your sniffer can tell when milk is rancid, but it can’t tell you if an oyster is safe. Oysters contaminated by V. vulnificus don’t smell or taste “off.” You also can’t fight this bacterium by dousing oysters in hot sauce or drowning them in vodka and “shooting” them down the hatch. And once oysters have been shucked from their shells, they should be cooked before consuming, not eaten raw.

Related: 5 Surprising Sushi Do’s and Don’ts

Jennifer Kelly Geddes is a New York City-based writer and editor who specializes in parenting, health and child development. She’s also the mom of two teen girls.