The actress has been battling symptoms of the virus since March, when she said she began experiencing fever and headache.
"Thought I'd show you what #COVID19 does to your hair," Milano tweeted along with the video. "Please take this seriously."
In the video she shows her clean detangling brush before brushing her wet hair.
"I just wanted to show you the amount of hair that is coming out of my head as a result of COVID," Milano said in the video.
Holding up a large clump of hair in front of the camera she added, "One brushing, this is my hair loss from COVID-19. Wear a d*** mask."
In an interview with CNN's Chris Cuomo on PrimeTime and infectious disease expert Dr. William Schaffner last week, the actress said she was waiting for advice from doctors on what to do now that she is in recovery, noting that it's not clear what next steps she should take.
"My question is there is no guidance on what to do once you recover. I don't know if I should go get my heart checked, my lungs checked. There's concerns about vascular system. Do I need to go get a panel for all of that?"
"There's no guidance because this is all so new," she added.
Schaffner said while there are no next steps that have been established yet, anyone still experiencing symptoms like Milano should continue to see their primary physician for care.
Milano has been suffering with several symptoms for months, she said in an Instagram post last week.
"This was me on April 2nd after being sick for 2 weeks," she posted along with a photo showing her wearing a breathing apparatus.
"I had never been this kind of sick. Everything hurt. Loss of smell," she wrote. "It felt like an elephant was sitting on my chest. I couldn't breathe. I couldn't keep food in me. I lost 9 pounds in 2 weeks.
"I basically had every COVID symptom," Milano wrote, adding that although she had tested negative for the virus twice, she has since tested positive for antibodies.
"I am POSITIVE for COVID antibodies," she wrote. "I had COVID-19. I just want you to be aware that our testing system is flawed and we don't know the real numbers."
The actress implored her followers to wear masks, social distance and wash their hands because she doesn't want anyone else to feel as horrible as she did.
"I also want you to know, this illness is not a hoax," she added. "I thought I was dying. It felt like I was dying."
"I don't want anyone to feel the way I felt."