The Cruel Intentions star is mum to son Rocky James and daughter Charlotte with husband Freddie Prinze, Jr. and late on Thursday (12Jan17) the concerned mum had to take her five-year-old boy to the hospital after he began to experience breathing difficulties.

"Well I made it 7 years before I had to take one of my children to the ER (I think that's a pretty good stretch)," she wrote on Instagram on Friday (13Jan17). "It was a long night and apparently a nasty virus, but thankfully Rocky was released."

Gellar went on to heap praise on the doctors and nurses who helped to get her son back on his feet.

"I'm not going to lie, watching your child not be able to breathe, is the most helpless I have ever felt," she added. "Thank you to all the great doctors and nurses (and staff) who work tirelessly 24 hours a day to help. And thank you to his big sister, Charlotte who would not leave his side. (The best moment was when I was filling out his paperwork, and I was asked if Rocky was single- laughter is definitely a great medicine)."

The actress has yet to reveal exactly what caused Rocky's condition, but during his hospitalisation, she helped to keep his mind off his health issues with the use of an iPhone.

"Thank goodness for #iphones and #inspectorgadget when your little one is sick in the ER," she wrote on Twitter, alongside a photo of her boy watching the cartoon.

She then assured fans, "(He's better and resting at home now #nastyvirus)".