(NewsNation) — An overlooked symptom of COVID-19 can cause long-term issues in many patients, according to an article published in the British Medical Journal. 

Common symptoms of COVID-19 include a sore throat, congestion, fatigue, muscle aches and fevers. Earlier in the pandemic, it was also common to lose one’s sense of smell or taste. 

According to the British Medical Journal, COVID-19 can also cause stomach and gastrointestinal issues such as lack of appetite, nausea and vomiting, diarrhea and abdominal pain. The journal states that around 50% of people experience some of these symptoms after an infection. 

The COVID-19 virus particles that cause lung illness also infect the gastrointestinal tract, which consists of the esophagus, stomach, small intestines and colon. Dr. Christopher Vélez said in an article published by Harvard Medical School that these virus particles can trigger abdominal pain and diarrhea for those with COVID-19. 

Many researchers have observed that the virus can cause long-lasting symptoms, referred to as “long COVID.” Reported effects of this often include tiredness, breathing difficulty, heart rhythm changes and muscle pain. 

Some medical professionals believe that chronic gut symptoms could be occurring as a form of long-term COVID-19. Vélez wrote that one possible insight is post-infectious irritable bowel syndrome, which is when the network of nerves that connects the gut and the brain is disrupted by something such as the stomach flu. 

These nerves could be disrupted by COVID-19 long after the virus causing the illness is gone. 

“Even if the process of digestion remains normal, you may frequently have symptoms like pain or a distressing change in your bowel movements, such as diarrhea or constipation,” Vélez said in the article. 

A study from the University of Oklahoma College of Medicine found a connection between COVID-19 and gastrointestinal symptoms. Dr. William Tierney, who led the study, said there is “clear evidence” linking the two. 

“COVID could be the trigger for a patient’s long-term digestive symptoms,” Tierney said.