Long COVID syndrome, also known as post-COVID, is more than fatigue and shortness of breath. Symptoms such as headaches, brain fog and ringing in the ears have been reported, and recently, physicians are seeing more patients with gastrointestinal problems. Greg Vanichkachorn, M.D., director of Mayo Clinic's COVID Activity Rehabilitation Program, describes the most common symptoms.

Patients in the rehabilitation program are reporting a variety of digestive issues, from mild nausea and decreased appetite to severe constipation and food intolerance, physical reactions to certain foods, says Dr. Vanichkachorn, a physician in Mayo Clinic’s Division of Public Health, Infectious Diseases.

“What we have seen firsthand has also been documented in medical literature,” he adds.  Among 147 patients with no prior gastrointestinal problems, 16% reported having new digestive symptoms roughly 100 days after their COVID-19 infection, according to a study published in March. The most common symptoms included:

• Abdominal pain: 7.5%
• Constipation: 6.8%
• Diarrhea: 4.1%
• Vomiting: 4.1%

Similarly, in a study published in April, researchers found that patients with long COVID were experiencing conditions known as disorders of gut brain interaction. Symptoms with this condition include heartburn, trouble swallowing, irritable bowel syndrome, constipation, diarrhea, bloating and incontinence.

“While we are not sure yet, there are several possible ways the COVID-19 infection could cause gastrointestinal problems,” Dr. Vanichkachorn says. “For example, the lining of the gut has a large amount of the receptors that the SARS-COV2 virus uses to invade cells. The general inflammation caused by the infection can also disrupt the normal bacteria that live in the gut and stimulate some of the gastrointestinal system’s nerves.”

Someone experiencing these symptoms as part of post-COVID syndrome should make sure they are hydrated and eat a healthy diet, Dr. Vanichkachorn advises. Fad and extreme diets have not been found to be helpful in long COVID, he adds.

“Instead, we recommend a Mediterranean diet with a reduction in processed foods. Second, avoid using lots of over-the-counter products to treat your symptoms,” Dr. Vanichkachorn says. “Sometimes, this can make the problem worse. Instead, speak to your medical professional first to develop a treatment plan.”

Dr. Vanichkachorn and colleagues at Mayo Clinic are conducting research aimed at offering more treatments to help patients with long COVID feel better faster. For more information, see the Mayo Clinic Connect Post-COVID Recovery Blog.