It's a condition that causes them to experience big changes in their blood pressure and often causes them to faint.
Take Kimberley Brazelton of East Bell for example. She told ABC7 sometimes, she forgets what she's doing.
"I put a spoon inside of a blender as it was going," she recalled. "Just not something I would do normally."
Nothing has been normal since the former emergency room nurse contracted COVID more than a year ago. It was right before she was about to get the vaccine. She and her entire family all had mild cases.
They got better, but Brazelton's symptoms got worse.
"Shortness of breath. Felt like my heart was jumping out of my chest. Dizzy. There's good days and bad days, so it's pretty inconsistent," she said.
At one point, Brazelton had blood pooling in her feet. She went to the COVID Heart Clinic at Loma Linda University Health.
Cardiologist Dr. Purvi Parwani said she's seeing many cases of the virus triggering postural orthostatic tachycardia syndrome or POTS for short.
"It's a condition where the heart rate goes up when we change position by at least 30 points or more," said Parwani.
Inflammation from infection can throw off the body's autonomic nervous system.
"When we get dysregulation of this nervous system, the heart rate and blood pressure, kind of also get out of range. In this case, it would cause palpitations and dizziness," said Parwani.
Some people with POTS pass out when they stand up. Treatment varies from patient to patient but often includes blood pressure medicine, lifestyle changes and balance therapy.
But could COVID-related POTS be different?
Doctors are seeing it across the country and are working together to find answers.
"We are always looking out for new literature, because this disease, however much we talk about it, it's still relatively new," Parwani said.
Brazelton said she is slowly getting better and looks forward to the day that she can return to working in the emergency room.
"I still push myself as much as I can and fight. Mind over matter. That's all I keep telling myself. I can get through this," she said.