Raw Oysters & Diarrhea

Raw oysters might put you in the mood for romance, but if you're not careful they may also put you in the bathroom. If you suffer from diarrhea after eating raw oysters, it may be the result of a shellfish allergy or food poisoning, causing the gastrointestinal tract to quickly rid itself of an unwanted substance. Diarrhea is a normal condition that typically lasts for a few days, but in some cases may continue longer, according to MedlinePlus. Diarrhea can lead to dehydration and, if it continues, should be treated under the supervision of your physician.

A plate of raw oysters on ice. (Image: stebren/iStock/Getty Images)

Shellfish Allergy

The Food Allergy Initiative states that a shellfish allergy is considered the most common food allergy found in adults. The allergy is considered a chronic condition that is incurable, but manageable. A shellfish allergy can cause a severe allergic reaction, or anaphylaxis. During an allergy to oysters, your immune system doesn't recognize the proteins found in the seafood and attempts to fight them off with antibodies and histamines. Histamine leads to inflammation in various soft tissue in the body that causing swelling and irritation.

Food Poisoning

Food poisoning is a condition where you ingest a certain food that contains viruses, toxins, bacteria or parasites, according to MedlinePlus. Whenever you eat any seafood in its raw state you are at greater risk for experiencing food poisoning. Food poisoning symptoms typically develop two to six hours after eating the food, but can delay until the next day.


Both conditions will produce gastric symptoms, such as nausea, vomiting, stomach pain, abdominal cramping, bloating, gas and diarrhea. During an allergic reaction to oysters, the increased histamine in the intestines cause them to swell and lead to digestive difficulties. An allergy to oysters will be accompanied by various other symptoms, unrelated to the digestive tract. These include asthma, skin rashes and nasal congestion, according Food Allergy Research and Education.


Minor allergy symptoms can be treated with antihistamines, according to FARE. Diarrhea from food poisoning is treated with increased rest, drinking more liquids and avoiding certain foods. Drink water, juice and soup broth but avoid the use of apple and pear juices because they can make your condition worse. Once your diarrhea begins to subside, incorporate small meals of bland foods, such as rice, eggs, chicken and toast. Avoid consuming fatty foods, highly seasoned foods and dairy products until the diarrhea completely subsides.


Diarrhea accompanied with facial swelling, hives, shortness of breath, mental confusion and lightheadedness is a sign of anaphylaxis. The extreme levels of histamine released causes the body to experience a state of shock and anxiety, according to MedlinePlus.com.

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