It's estimated 25 million Americans are affected by the flu annually, but did you know it can attack your heart?
Doctors say it's another reason not to forget to your flu shot.
Because of this virus, one man nearly ended up getting a heart transplant. Alfino Donastorg has always been active, but two years ago he got sick.
"I thought it was just a common cold," said Donastorg.
When he became short of breath, he ended up in the hospital.
"They were telling me my heart was failing, heart transplant is imminent," he said.
Donastorg had cardiomyopathy - a weakening of the heart muscle that led to congestive heart failure at age 38.
"He was a healthy young man who was just exposed to the flu and it attacked his heart," said Dr. Yordanka Reyna, a cardiologist who specializes in advanced heart failure and transplant.
Reyna said the flu causes inflammation that can quickly lead to cardiac symptoms. "Shortness of breath, leg swelling, a cough at night," said Reyna. She added heart disease due to the flu can happen to anyone.
"Go to the emergency room, go to the doctor, they can test very easily and very fast," said Reyna.
Doctors worked to keep Donastorg off the heart transplant list.
"We managed to get him better with intravenous medicines, diuretics," Reyna said.
Donastorg still can't believe how close he came to death.
"Your body tells you, 'Hey listen, there's something that's not right, please get checked out,'" he said.
His message to everyone is to not ignore the signs!
Reyna reminds everyone to get vaccinated for the flu every season because the strains change. She said if you do have the flu and you take an anti-viral medication like Tamiflu, but don't improve within a week, call your doctor or get to the emergency room.