Mayim Bialik has tested positive for Covid-19 and says it's been rough.

"The Big Bang Theory" star and "Jeopardy!" host posted a video on her verified Instagram account Monday about her diagnosis and how she has been struggling with it.

She said, "I have Covid and it's no joke over here," she said. "It's very exhausting, the exhaustion is very special.

She said, I had mononucleosis when I was in college and the exhaustion hits like that where you cannot be awake. You can try to be awake but then all of a sudden you need to sleep."

Bialik, who is vaccinated and boosted, also shared, "I do have asthma, I do have a thyroid condition which means it's an immune compromised situation."

She also urged her followers to stay vigilant.

"I'm feeling a whole bunch of regret that I ever took my mask off ever in the world, like even outside," she said.

"I'm feeling a lot of fear. Why did I ever go out? Why did I think that anything was fine ever?"

Bialik posted an update on the Instagram account for her podcast "Bialik Breakdown" on Tuesday, saying she was feeling better but still had congestion, tiredness and anxiety about going outside.