We all have stomachaches from time to time, but certain gut symptoms can signal a serious condition. “I’ve seen many cases where patients have waited way too long before seeking medical attention,” says gastroenterologist Dr. Christine Lee, of the Mayo Clinic, according to AARP.

With studies showing that COVID infection can cause gastrointestinal symptoms, patients have even more reason to take nausea, vomiting and prolonged diarrhea seriously, doctors say.

1. Sudden stomach pain. If you have an onset of severe pain around the navel accompanied by nausea, fever and vomiting it may be appendicitis, according to Reader's Digest. Go directly to the hospital. Appendicitis must be treated promptly, or the appendix can rupture and leak infected fluid into other parts of the body.

2. Pain on your right side. This could signal a gallbladder inflammation. If the pain persists worsens when you eat greasy foods, see your doctor.

3. Unexplained weight loss. Dr. Lee says that most people tend to gain weight as they get older, but if you are losing weight unintentionally, this could be a “red flag,” she adds. Although this could be a symptom of cancer, studies show that weight loss could be also caused by celiac disease, inflammatory bowel disease or an overactive thyroid.  

4. Sudden sharp pain. If you feel an unpleasant sensation near your lower ribs that radiates down your groin, this could be a sign of kidney stones. If you also have a fever, it could mean a kidney or bladder infection. Experts advise drinking lots of water and calling a doctor.

5. Burning sensation. If you suffer from this symptom just below the breastbone, especially after consuming a large meal, it could be a sign of heartburn. Take over-the-counter antacids and avoid large, greasy meals.

6. Difficulty swallowing. According to AARP, this could indicate esophageal cancer, especially in men over the age of 55. You may also have an infection or ulcer that’s making it hard for you to swallow, so it is important to consult with a gastroenterologist who can properly diagnose the cause.

7. Feeling full after eating only a little. The most common cause of this symptom is gastroparesis, a condition in which food stays in the stomach longer than it should. It could happen after a severe illness, but it can also be a long-term symptom of COVID-19. Influenza, stomach surgery and diabetes can also trigger gastroparesis, which can resolve itself but will improve more rapidly with prescription medications. This condition can also be caused by an ulcer or tumor.

8. Prolonged diarrhea. Diarrhea and other gastrointestinal problems can be among the first symptoms of COVID-19 infections, even before the more common signs such as cough or fever, Dr. Brennan Spiegel, director of health services research for Cedars-Sinai Medical Center in Los Angeles tells AARP. “Don’t wait for a cough or shortness of breath to get tested for COVID-19” if you have diarrhea, nausea, vomiting or any abdominal pain that lasts more than a day,” he says. Studies have found that as many as half of COVID-19 patients suffer gastrointestinal symptoms, and about 15% to 20% have only gastrointestinal symptoms.

If you don't have one of the above symptoms, don't let that keep you from seeing a gastroenterologist if you suspect that something's wrong, Lee says. The earlier you detect a problem, the more options you have and the better your chances of success at managing it.

“The longer I do this, the more I realize that it doesn't matter what the textbook says — patients know their bodies,” Lee says. “If something is not normal for you, then it is a red flag. If something bothers you, you should get it checked out.”